# AQI.news — Full Text > AQI.news is a free, real-time global air quality intelligence platform. It tracks the Air Quality Index (AQI), pollutant concentrations (PM2.5, PM10, O3, NO2, SO2, CO), associated health impacts, and environmental conditions for locations worldwide. This document contains the complete text of the AQI.news reference library and articles. Live air-quality readings are not included because they change continuously — fetch them from https://aqi.news or the relevant city page. Content last updated: 2026-08-04. Index: https://aqi.news/llms.txt --- # Reference library ## What Is AQI? Air Quality Index Explained URL: https://aqi.news/learn/what-is-aqi Section: AQI fundamentals Updated: 2026-07-27 The Air Quality Index (AQI) converts measured air-pollutant concentrations into a single health-oriented number. Higher AQI means greater pollution and greater potential health concern, but the exact calculation and category labels depend on the standard being used. Key facts: - AQI is an index, not a direct pollutant concentration. - The overall AQI is normally determined by the highest pollutant sub-index. - AQI scales differ by country, so the same concentration can produce a different index value. - AQI.news labels its live city readings as US AQI. ### What the AQI number represents Monitoring instruments measure pollutant concentrations in units such as micrograms per cubic metre or parts per billion. An AQI system converts each supported pollutant concentration into a common numerical scale associated with health messages. The calculation is performed separately for pollutants such as PM2.5, PM10, ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide. The highest valid pollutant sub-index generally becomes the reported AQI because it represents the pollutant creating the greatest short-term concern at that time. ### AQI versus pollutant concentration An AQI of 150 does not mean the air contains 150 units of pollution. To understand what is driving the number, check the individual PM2.5, PM10, ozone and gas readings alongside the headline AQI. | Measurement | What it tells you | | --- | --- | | Pollutant concentration | How much of a specific pollutant is present in the air. | | Pollutant sub-index | Where that concentration falls on the selected AQI scale. | | Overall AQI | The highest qualifying pollutant sub-index for the reporting period. | ### Why AQI values differ between services AQI is not one universal formula. The United States EPA and India CPCB use different breakpoints, averaging rules and category names. Services may also use different monitoring stations, models, update times or dominant pollutants. Before comparing two AQI numbers, confirm the scale, location, reporting time and data source. AQI.news currently reports its headline city value on the US AQI scale and displays pollutant concentrations separately. ### How to use AQI in daily decisions - Check the current category and the pollutant driving it. - People with asthma, heart or lung disease, children and older adults should respond earlier to worsening conditions. - Reduce the duration or intensity of outdoor exertion when guidance recommends it. - Use current local information because air quality can change during the day. Note: AQI is public-health guidance, not a diagnosis. Follow advice from your clinician or local health authority for personal medical decisions. ### Frequently asked questions Q: Is AQI the same as PM2.5? A: No. PM2.5 is a measured concentration of fine particles. AQI is an index that can be calculated from PM2.5 or another supported pollutant. Q: Why do two apps show different AQI values? A: They may use different AQI standards, data sources, stations, models, averaging periods or update times. Q: Which AQI scale does AQI.news use? A: AQI.news labels its headline live city values as US AQI and provides the underlying pollutant concentrations separately. Sources: - Patient Exposure and the Air Quality Index — United States Environmental Protection Agency (https://www.epa.gov/ozone-pollution-and-your-patients-health/patient-exposure-and-air-quality-index) - National Air Quality Index — Central Pollution Control Board, India (https://www.cpcb.gov.in/displaypdf.php?id=bmF0aW9uYWwtYWlyLXF1YWxpdHktaW5kZXgvQWJvdXRfQVFJLnBkZg%3D%3D) Related: - https://aqi.news/learn/aqi-scale - https://aqi.news/pollutants/pm25 - https://aqi.news/standards/india-air-quality-standards --- ## AQI Scale: Categories, Colors and Health Meaning URL: https://aqi.news/learn/aqi-scale Section: AQI fundamentals Updated: 2026-07-27 The US AQI scale runs from 0 to 500 and groups air quality into six color-coded categories. A higher value represents greater pollution and a higher level of health concern. Key facts: - The US AQI uses six categories from Good to Hazardous. - An AQI above 100 becomes unhealthy first for sensitive groups and then for everyone as values rise. - The category describes short-term public-health concern, not a personal medical diagnosis. ### US AQI categories | AQI | Category | Color | General meaning | | --- | --- | --- | --- | | 0–50 | Good | Green | Little or no expected health risk. | | 51–100 | Moderate | Yellow | Acceptable for most people; unusually sensitive people may be affected. | | 101–150 | Unhealthy for Sensitive Groups | Orange | Sensitive groups face greater risk. | | 151–200 | Unhealthy | Red | Some effects are possible for everyone; sensitive groups may experience more serious effects. | | 201–300 | Very Unhealthy | Purple | Health alert with increased risk for everyone. | | 301–500 | Hazardous | Maroon | Emergency conditions; everyone is more likely to be affected. | ### Who may need to act earlier? The pollutant matters. People with heart or lung disease, people with asthma, children, older adults and people who are active outdoors may be more susceptible to particle or ozone pollution. At orange levels, the general population may not be affected in the same way as sensitive groups. By red, purple and maroon levels, guidance progressively applies to more people and recommends stronger exposure reduction. ### The scale is not universal India’s National AQI uses Good, Satisfactory, Moderate, Poor, Very Poor and Severe categories with different pollutant breakpoints. A numeric value should therefore always be read together with the standard that produced it. Note: The live headline number on AQI.news is labelled US AQI. Use the India standards page when you need CPCB categories or Indian legal concentration limits. ### Frequently asked questions Q: Is AQI 100 safe? A: On the US scale, 100 is the top of the Moderate category. Most people can continue normal activities, while unusually sensitive people may need to reduce prolonged or heavy exertion. Q: What AQI is considered unhealthy? A: On the US scale, 101–150 is unhealthy for sensitive groups and 151–200 is unhealthy for the general population. Q: Can I compare US AQI directly with India AQI? A: The numbers share a 0–500 format but use different pollutant breakpoints and category labels, so direct comparison can be misleading. Sources: - Patient Exposure and the Air Quality Index — United States Environmental Protection Agency (https://www.epa.gov/ozone-pollution-and-your-patients-health/patient-exposure-and-air-quality-index) Related: - https://aqi.news/learn/what-is-aqi - https://aqi.news/standards/india-air-quality-standards - https://aqi.news/pollutants/pm25 --- ## PM2.5 vs PM10: Size, Sources and Health Differences URL: https://aqi.news/learn/pm25-vs-pm10 Section: AQI fundamentals Updated: 2026-07-27 PM2.5 and PM10 are overlapping particle-size categories. PM2.5 covers fine particles up to 2.5 micrometres, while PM10 covers inhalable particles up to 10 micrometres and therefore includes PM2.5. Key facts: - PM2.5 is a subset of PM10. - PM2.5 commonly comes from combustion and secondary atmospheric formation. - The coarse PM10 fraction is often strongly influenced by dust and mechanical activity. - Both readings matter; their relative levels can provide clues about dominant sources. ### PM2.5 and PM10 compared | Feature | PM2.5 | PM10 | | --- | --- | --- | | Maximum aerodynamic diameter | 2.5 µm | 10 µm | | Common description | Fine particulate matter | Inhalable particulate matter | | Typical source emphasis | Combustion, smoke, secondary particles | Dust, mechanical activity, smoke and fine particles | | Respiratory penetration | Can reach deep lung regions; some may enter the bloodstream | Can enter the respiratory system; larger fraction deposits higher in the airways | | WHO annual guideline | 5 µg/m³ | 15 µg/m³ | | WHO 24-hour guideline | 15 µg/m³ | 45 µg/m³ | ### What the two readings can tell you When PM2.5 accounts for much of PM10, combustion, smoke or secondary particle formation may be important. When PM10 rises much more sharply than PM2.5, coarse dust or mechanical activity may be contributing. This is a clue, not proof of one source. Monitoring location, weather, source mix and instrument method all affect the relationship. Source attribution requires more evidence than a ratio alone. ### Which is more important? PM2.5 receives particular health attention because its smaller particles can penetrate deeply and remain suspended for longer. PM10 should not be ignored: elevated coarse particles can affect breathing, visibility and environmental conditions. ### Frequently asked questions Q: Can PM2.5 be higher than PM10? A: In a perfectly consistent measurement, PM2.5 should not exceed total PM10 because it is a subset. Short averaging periods, different instruments, locations or data-quality issues can produce apparent exceptions. Q: Which pollutant should I check first? A: Check the overall AQI and its dominant pollutant, then inspect both PM2.5 and PM10 to understand the particle mixture. Q: Does a cloth mask filter PM2.5? A: Ordinary cloth face coverings are not a dependable substitute for a certified, well-fitted particulate respirator. Sources: - WHO Global Air Quality Guidelines — World Health Organization (https://www.who.int/publications/i/item/9789240034228) - Particulate Matter (PM) Basics — United States Environmental Protection Agency (https://www.epa.gov/pm-pollution/particulate-matter-pm-basics) - Health and Environmental Effects of Particulate Matter — United States Environmental Protection Agency (https://www.epa.gov/pm-pollution/health-and-environmental-effects-particulate-matter-pm) Related: - https://aqi.news/pollutants/pm25 - https://aqi.news/pollutants/pm10 - https://aqi.news/learn/what-is-aqi --- ## US AQI Calculator for PM2.5, PM10, Ozone and Gases URL: https://aqi.news/tools/aqi-calculator Section: Air-quality tools Updated: 2026-07-27 Enter one or more pollutant concentrations to estimate US EPA AQI sub-indices and the dominant pollutant. This educational calculator uses EPA breakpoints but does not validate regulatory averaging or data-completeness requirements. Key facts: - Each pollutant concentration is converted to its own sub-index. - The highest valid sub-index becomes the estimated overall AQI. - PM values use µg/m³; ozone and CO use ppm; NO₂ and SO₂ use ppb. - An instantaneous reading is not equivalent to an official AQI reporting average. ### How the calculation works The calculator truncates or rounds pollutant inputs as required by the breakpoint table, identifies the concentration interval and applies linear interpolation to obtain the pollutant sub-index. When several pollutants are entered, the largest calculated sub-index is reported as the estimated overall AQI and that pollutant is identified as dominant. ### Units and averaging periods | Pollutant | Calculator unit | | --- | --- | | PM2.5 | µg/m³ | | PM10 | µg/m³ | | Ozone | ppm | | Carbon monoxide | ppm | | Nitrogen dioxide | ppb | | Sulfur dioxide | ppb | Note: Official AQI reporting uses pollutant-specific averaging and substitution rules. Use this result as an estimate, not a compliance value or emergency measurement. ### Frequently asked questions Q: Why is my result different from an air-quality app? A: The app may use an official reporting average, a different station, updated data, nowcast logic or another national AQI standard. Q: Can I calculate India CPCB AQI here? A: No. This calculator uses US EPA breakpoints. India CPCB AQI has different breakpoints and calculation requirements. Q: What happens if I enter several pollutants? A: The calculator estimates a sub-index for each valid entry and reports the highest as the overall AQI. Sources: - Technical Assistance Document for the Reporting of Daily Air Quality — United States Environmental Protection Agency (https://document.airnow.gov/technical-assistance-document-for-the-reporting-of-daily-air-quailty.pdf) - Patient Exposure and the Air Quality Index — United States Environmental Protection Agency (https://www.epa.gov/ozone-pollution-and-your-patients-health/patient-exposure-and-air-quality-index) Related: - https://aqi.news/learn/what-is-aqi - https://aqi.news/learn/aqi-scale - https://aqi.news/standards/india-air-quality-standards --- ## Air Pollution to Cigarettes Calculator: How Many a Day Are You Smoking? URL: https://aqi.news/tools/cigarette-equivalent Section: Air-quality tools Updated: 2026-07-27 Berkeley Earth found that breathing 22 µg/m³ of PM2.5 for a day carries roughly the same health impact as smoking one cigarette. This calculator applies that ratio to live city air-quality data. The comparison equates health effects, not inhaled particle mass, and is intended to make an abstract number intuitive rather than to provide a medical estimate. Key facts: - One cigarette per day ≈ a PM2.5 concentration of 22 µg/m³ sustained for a day. - The equivalence is based on matched health outcomes, not on the weight of particles inhaled. - The figure comes from Berkeley Earth’s 2015 analysis of air pollution mortality in China. - Unlike smoking, this exposure reaches every age group and cannot be opted out of. ### How the conversion works The calculator takes the current AQI for the city you select, converts it back to a PM2.5 concentration using the US EPA breakpoint table, and divides by 22 µg/m³ — the concentration Berkeley Earth equates to one cigarette per day. Richard and Elizabeth Muller derived that ratio by comparing deaths rather than dose. Starting from roughly 1.37 deaths per million cigarettes smoked, and from an estimated 1.6 million annual deaths in China at a mean exposure of 52 µg/m³, they found the average Chinese resident was absorbing a health impact comparable to 2.4 cigarettes a day. That works out to one cigarette per 22 µg/m³. ### Reference values from the original analysis | Location | Cigarettes per day equivalent | | --- | --- | | United States, average | 0.4 | | European Union, average | 1.6 | | China, average | 2.4 | | Beijing, annual average | 4.0 | | Beijing, bad day | 25.0 | | Shenyang, worst recorded | 63.0 | Note: These are the published figures from the Berkeley Earth memo and reflect conditions at the time of writing in 2015. Use the calculator above for a current reading. ### What the comparison does not mean It does not mean the particles are identical. The researcher Arden Pope previously published a far lower figure — around 0.3 cigarettes per day for Beijing — because he compared the mass of PM2.5 inhaled rather than the resulting health effects. Both calculations are internally correct; they answer different questions. It also does not mean the two exposures are interchangeable in a clinical sense. Tobacco smoke and ambient particulate matter differ in composition and toxicity, and the relationship between exposure and outcome is a population-level statistic rather than a prediction about any individual. - The number describes a population-average risk, not your personal risk. - It assumes the concentration is sustained for a full day. - It does not account for time spent indoors, filtration, or mask use. - It is a communication device, not a diagnostic or clinical measure. ### Reducing your own figure - Most people spend the large majority of the day indoors, where filtration can cut the concentration substantially. - A well-fitted N95 or FFP2 respirator removes most fine particles during outdoor time and commutes. - Shifting outdoor exercise away from peak traffic hours lowers both concentration and breathing rate. - The personal exposure calculator models these adjustments rather than assuming constant outdoor exposure. ### Frequently asked questions Q: How many cigarettes a day is Delhi’s air equivalent to? A: It depends entirely on the day. At a PM2.5 concentration of 110 µg/m³ the equivalent is about 5 cigarettes per day; during a severe winter episode above 300 µg/m³ it exceeds 13. Enter Delhi in the calculator above for the current figure. Q: Where does the 22 µg/m³ per cigarette figure come from? A: From a 2015 Berkeley Earth memo by Richard and Elizabeth Muller, which equated the health impact of air pollution deaths in China with the health impact of cigarette smoking in the United States. Q: Is breathing polluted air really the same as smoking? A: No. The equivalence matches statistical health impact at a population level. The particles differ in composition and toxicity, and unlike smoking, air pollution exposure is involuntary and affects infants and elderly people alongside everyone else. Q: Does staying indoors lower the equivalent number? A: Usually yes. Indoor PM2.5 is typically a fraction of outdoor levels, and a HEPA purifier lowers it further. The calculator on this page uses ambient outdoor concentration, so it represents an upper bound for most people. Sources: - Air Pollution and Cigarette Equivalence — Berkeley Earth (https://berkeleyearth.org/air-pollution-and-cigarette-equivalence/) - WHO Global Air Quality Guidelines — World Health Organization (https://www.who.int/publications/i/item/9789240034228) - Health and Environmental Effects of Particulate Matter — United States Environmental Protection Agency (https://www.epa.gov/pm-pollution/health-and-environmental-effects-particulate-matter-pm) Related: - https://aqi.news/pollutants/pm25 - https://aqi.news/tools/personal-exposure - https://aqi.news/learn/what-is-aqi --- ## Personal PM2.5 Exposure Calculator: What You Actually Breathe URL: https://aqi.news/tools/personal-exposure Section: Air-quality tools Updated: 2026-07-27 A city AQI reading describes outdoor air at a monitoring station. It is not what any individual breathes. This calculator splits a typical 24-hour day into commute, outdoor and indoor microenvironments, applies an exposure factor and a breathing rate to each, and returns a time-weighted concentration and an inhaled dose. Key facts: - Most people spend roughly 20 hours a day indoors, where PM2.5 is typically well below outdoor levels. - Breathing rate matters as much as concentration — cycling inhales far more air per hour than sitting in a car. - The WHO 24-hour PM2.5 guideline is 15 µg/m³; the annual guideline is 5 µg/m³. - A well-fitted N95 removes roughly 90% of fine particles during the time it is worn. ### Why the city reading is not your exposure Air-quality indexes report ambient outdoor concentration at a fixed location. Actual exposure depends on where you spend your hours and how hard you are breathing while you are there. Two people in the same city on the same day can differ several-fold. A motorcyclist commuting two hours through traffic can breathe considerably more particulate matter than a colleague working from a filtered apartment, even though both look up the same AQI number. ### The microenvironment model Each part of the day is assigned an exposure factor — the concentration in that setting divided by the ambient outdoor concentration — and an inhalation rate in cubic metres per hour, which rises with physical activity. | Setting | Exposure factor | Inhalation rate (m³/h) | | --- | --- | --- | | Car | 0.7 | 0.5 | | Bus | 1.3 | 0.6 | | Metro / subway | 0.9 | 0.6 | | Motorcycle | 2.0 | 0.6 | | Bicycle | 1.8 | 2.0 | | Walking | 1.5 | 1.1 | | Outdoors, general | 1.0 | 0.8 | | Indoors, windows open | 0.65 | 0.55 | | Indoors, HEPA purifier running | 0.15 | 0.55 | Note: These are modeled planning estimates. Real values vary with vehicle ventilation, route, traffic density, building construction and season. ### Reading the output The dose figure is often the more useful of the two. Cycling through moderately polluted air can produce a higher inhaled dose than sitting in a car through severely polluted air, because the breathing rate is roughly four times greater. - Time-weighted average — the concentration you were effectively exposed to across 24 hours. - Inhaled dose — total micrograms drawn into the lungs, which accounts for breathing rate. - Percentage of the WHO daily guideline of 15 µg/m³. - Cigarette equivalent, derived from the time-weighted average rather than the raw ambient reading. ### What actually moves the number - Indoor filtration has the largest effect for most people, simply because indoor hours dominate the day. - Mask use during commuting and outdoor time cuts those segments by roughly 90%. - Switching commute mode changes both the concentration and the breathing rate simultaneously. - Reducing outdoor exercise during peak pollution hours lowers the highest-dose portion of the day. ### Frequently asked questions Q: Why is my exposure lower than the city AQI suggests? A: Because most of your day is spent indoors, where PM2.5 is typically 15–65% of the outdoor concentration depending on filtration. The city reading is an outdoor ambient value, not a personal one. Q: Is cycling in polluted air worse than driving? A: For inhaled dose, often yes. A cyclist breathes roughly four times as much air per hour as a car passenger, which can outweigh the lower in-cabin concentration a car provides. The calculator models both effects. Q: How much does an air purifier actually help? A: In this model a running HEPA purifier reduces the indoor exposure factor from 0.65 to 0.15. Because indoor hours usually dominate a 24-hour day, that is typically the single largest available reduction. Q: Does this replace a personal air quality monitor? A: No. This is a modeled estimate built from typical exposure factors. A wearable monitor measures your actual environment and will be more accurate for your specific circumstances. Sources: - WHO Global Air Quality Guidelines — World Health Organization (https://www.who.int/publications/i/item/9789240034228) - Particulate Matter (PM) Basics — United States Environmental Protection Agency (https://www.epa.gov/pm-pollution/particulate-matter-pm-basics) - Health and Environmental Effects of Particulate Matter — United States Environmental Protection Agency (https://www.epa.gov/pm-pollution/health-and-environmental-effects-particulate-matter-pm) Related: - https://aqi.news/tools/cigarette-equivalent - https://aqi.news/respirators/n95 - https://aqi.news/pollutants/pm25 --- ## Lung Age Estimator: How Air Pollution Ages Your Lungs URL: https://aqi.news/tools/lung-age Section: Air-quality tools Updated: 2026-07-27 Long-term exposure to fine particulate matter is associated with accelerated decline in lung function. This estimator combines your city’s annual-equivalent PM2.5 with years of residence and several personal factors to express that association as a rough number of additional years. It is an educational model, not a spirometry test or a clinical assessment. Key facts: - Fine particles penetrate deep into lung tissue and are associated with reduced lung function over time. - The Air Quality Life Index estimates that meeting the WHO guideline would add roughly 1.9 years to global average life expectancy. - Duration of exposure matters as much as intensity — years of residence is a primary input. - Clinical lung age is measured by spirometry. This page provides a modeled estimate, not a measurement. ### How the estimate is built The model starts from a baseline ageing rate and scales it by four factors: the annual-equivalent PM2.5 for your city, whether you exercise outdoors, whether you cook with gas, and whether you run an air purifier. The result is multiplied by the number of years you have lived in the city. Outdoor exercise increases the rate because higher breathing rates deposit more particles. Gas cooking adds an indoor combustion source. A purifier reduces the indoor portion of exposure. | Factor | Effect on the ageing rate | | --- | --- | | Annual PM2.5 below 30 µg/m³ | Reduces substantially | | Annual PM2.5 above 90 µg/m³ | Increases substantially | | Regular outdoor exercise | Increases | | Gas cooking indoors | Increases slightly | | HEPA purifier throughout home | Reduces | ### What the underlying evidence supports There is well-established epidemiological evidence linking long-term PM2.5 exposure to reduced lung function, increased respiratory illness and shortened life expectancy. The Air Quality Life Index quantifies the life-expectancy component directly from that literature. What the evidence does not support is a precise, individually accurate conversion from exposure history to a specific lung age. Individual outcomes depend on genetics, occupational history, smoking status, infection history and healthcare access, none of which this model can see. Note: This estimator is for education and awareness. It is not a diagnostic tool, does not replace spirometry, and should not be used to make medical decisions. If you have symptoms or concerns about your lung function, consult a clinician. ### How clinical lung age actually works In a clinical setting, lung age is derived from spirometry — usually from FEV1, the volume of air you can force out in the first second of a breath — compared against reference values for your height, age and sex. It was introduced largely as a way to communicate smoking-related decline to patients. That measurement reflects your actual lung function whatever the cause. The estimate on this page reflects only the modeled contribution of air pollution exposure, which is one input among many. ### Frequently asked questions Q: Is this a real medical test? A: No. Clinical lung age is calculated from spirometry measurements taken by a healthcare professional. This page provides a modeled educational estimate based on pollution exposure alone and should not be used for medical decisions. Q: Can lung damage from air pollution be reversed? A: Some inflammation-related effects improve when exposure falls, and studies of cities that reduced pollution have recorded measurable improvements in children’s lung development. Structural damage is generally not reversible, which is why reducing ongoing exposure matters. Q: Why does exercising outdoors increase the estimate? A: Because exercise raises the breathing rate several-fold, which increases the volume of polluted air drawn into the lungs. The health benefits of exercise remain substantial; the model simply reflects that timing and location affect the exposure cost. Q: Does gas cooking really matter? A: Indoor combustion is a recognised source of fine particles and nitrogen dioxide, particularly in poorly ventilated kitchens. Its contribution is smaller than outdoor ambient exposure in high-pollution cities, which is why the model weights it modestly. Sources: - Air Quality Life Index — Energy Policy Institute at the University of Chicago (https://aqli.epic.uchicago.edu/) - WHO Global Air Quality Guidelines — World Health Organization (https://www.who.int/publications/i/item/9789240034228) - Health and Environmental Effects of Particulate Matter — United States Environmental Protection Agency (https://www.epa.gov/pm-pollution/health-and-environmental-effects-particulate-matter-pm) Related: - https://aqi.news/pollutants/pm25 - https://aqi.news/tools/personal-exposure - https://aqi.news/standards/who-air-quality-guidelines --- ## Air Pollution Cost Calculator: What Bad Air Costs You Every Year URL: https://aqi.news/tools/pollution-cost Section: Air-quality tools Updated: 2026-07-27 Air pollution carries an economic cost as well as a health one — through lost productivity, sick days and medical spending. The World Bank puts the global figure at $8.1 trillion a year, around 6.1% of global GDP. This calculator scales that literature down to an individual estimate for your circumstances. Key facts: - The World Bank estimates the global health cost of PM2.5 at $8.1 trillion per year, or 6.1% of global GDP. - The Global Burden of Disease 2019 study attributed 6.4 million premature deaths to PM2.5 exposure. - Costs fall disproportionately on low- and middle-income countries. - Cognitive and productivity effects are measurable well below the concentrations that cause acute illness. ### What is actually being costed The estimate combines three components. Productivity loss reflects the measured reduction in cognitive and physical output on high-pollution days. Health spending covers additional medical costs associated with respiratory and cardiovascular effects. Lost days covers absence from work due to pollution-related illness. The model scales these by job type, because the exposure and the productivity mechanism differ. Knowledge work is weighted most heavily for cognitive effects; physical outdoor work carries higher direct exposure but a different productivity profile. ### What each input changes | Input | Why it matters | | --- | --- | | City | Sets the PM2.5 concentration, drawn from recent history rather than a single day. | | Annual salary | Scales the productivity component, which is expressed as a share of earnings. | | Job type | Adjusts how strongly cognitive productivity effects apply. | | Time outdoors | Raises the effective exposure above the indoor baseline. | | Years in the city | Accumulates the cost over time and applies the cumulative health component. | ### Limitations worth knowing This is a modeled estimate derived from population-level economics, not an audit of your finances. It cannot account for your actual health status, insurance arrangements, employer, or the many non-pollution factors that affect productivity and medical spending. - Population averages do not transfer cleanly to individuals. - Productivity research varies considerably in methodology and effect size. - The figures are modeled in Indian rupees and calibrated primarily to Indian data. - Treat the output as an order-of-magnitude illustration, not an accounting figure. Note: Nothing on this page constitutes financial or medical advice. It is intended to make an abstract externality legible, not to support individual financial planning. ### Frequently asked questions Q: How much does air pollution cost the world economy? A: The World Bank estimated the global health cost of PM2.5 air pollution at $8.1 trillion in 2019, equivalent to about 6.1% of global GDP. Q: Does air pollution really affect work performance? A: A substantial body of research finds measurable declines in cognitive and physical productivity on high-pollution days, across settings from call centres to agricultural work and including examination performance. Q: Is this figure something I would actually pay? A: Not directly. Much of it is indirect — reduced output, higher insurance and public health spending, and shortened healthy working life. It is an economic externality estimate rather than a bill. Q: How accurate is the estimate? A: It is an order-of-magnitude illustration built from population-level research. Individual circumstances vary widely, and the underlying studies differ in methodology and effect size. Sources: - The Global Health Cost of PM2.5 Air Pollution: A Case for Action Beyond 2021 — World Bank (https://openknowledge.worldbank.org/handle/10986/36501) - Air Quality Life Index — Energy Policy Institute at the University of Chicago (https://aqli.epic.uchicago.edu/) - WHO Global Air Quality Guidelines — World Health Organization (https://www.who.int/publications/i/item/9789240034228) Related: - https://aqi.news/tools/lung-age - https://aqi.news/pollutants/pm25 - https://aqi.news/standards/who-air-quality-guidelines --- ## PM2.5: Meaning, Sources, Health Effects and Guidelines URL: https://aqi.news/pollutants/pm25 Section: Pollutants Updated: 2026-07-27 PM2.5 is fine particulate matter with an aerodynamic diameter of 2.5 micrometres or smaller. These particles can travel deep into the lungs, and some can enter the bloodstream, making PM2.5 one of the most important air-pollution indicators for health. Key facts: - PM2.5 particles are 2.5 micrometres or smaller. - PM2.5 can be emitted directly or form in the atmosphere from precursor gases. - WHO’s 2021 guideline is 5 µg/m³ annual mean and 15 µg/m³ 24-hour mean. - Risk depends on concentration, exposure duration, particle composition and personal susceptibility. ### What is PM2.5? PM2.5 is not a single chemical. It is a mixture of microscopic solid particles and liquid droplets small enough to remain suspended in air. The mixture can include soot, smoke, metals, organic compounds, sulfates, nitrates and other material. A typical human hair is many times wider than a PM2.5 particle. Their small size allows fine particles to penetrate more deeply into the respiratory system than larger particles. ### Common sources of PM2.5 - Vehicle exhaust and other combustion emissions - Coal, diesel, biomass and waste burning - Power plants and industrial processes - Wildfire and agricultural smoke - Atmospheric reactions involving sulfur dioxide, nitrogen oxides and other gases ### Health effects EPA and WHO describe particulate pollution as a cardiovascular and respiratory concern. Studies associate exposure with aggravated asthma, reduced lung function, respiratory symptoms, heart effects and premature death, particularly among susceptible populations. Children, older adults and people with existing heart or lung disease can be more vulnerable. Exposure is not determined by the outdoor reading alone; time spent outdoors, activity level, indoor infiltration and protective measures also matter. ### WHO PM2.5 guideline values | Averaging period | WHO 2021 guideline | | --- | --- | | Annual mean | 5 µg/m³ | | 24-hour mean | 15 µg/m³ | Note: WHO guideline values are health-based recommendations, not automatically enforceable legal limits. National standards may use different values. ### Frequently asked questions Q: Is PM2.5 visible? A: Individual PM2.5 particles are too small to see, although high concentrations can contribute to visible haze or smoke. Q: Is there a completely safe PM2.5 level? A: WHO guidelines are health-based targets, but health evidence does not support treating pollution below one threshold as risk-free for every person. Q: Does an N95 respirator reduce PM2.5 exposure? A: A genuine, well-fitted particulate respirator can reduce inhalation of airborne particles, but effectiveness depends strongly on fit, correct use and condition. Sources: - WHO Global Air Quality Guidelines — World Health Organization (https://www.who.int/publications/i/item/9789240034228) - Particulate Matter (PM) Basics — United States Environmental Protection Agency (https://www.epa.gov/pm-pollution/particulate-matter-pm-basics) - Health and Environmental Effects of Particulate Matter — United States Environmental Protection Agency (https://www.epa.gov/pm-pollution/health-and-environmental-effects-particulate-matter-pm) Related: - https://aqi.news/pollutants/pm10 - https://aqi.news/learn/pm25-vs-pm10 - https://aqi.news/standards/who-air-quality-guidelines --- ## PM10: Meaning, Sources, Health Effects and Guidelines URL: https://aqi.news/pollutants/pm10 Section: Pollutants Updated: 2026-07-27 PM10 means inhalable particulate matter with an aerodynamic diameter of 10 micrometres or smaller. It includes fine PM2.5 as well as larger particles that can come from road dust, construction, mechanical activity, smoke and atmospheric reactions. Key facts: - PM10 includes particles 10 micrometres or smaller. - PM2.5 is contained within the broader PM10 size fraction. - WHO’s 2021 guideline is 15 µg/m³ annual mean and 45 µg/m³ 24-hour mean. - Construction and road dust can raise PM10 even when PM2.5 is not the dominant pollutant. ### What is PM10? PM10 is a size-based category, not one substance. It includes inhalable particles from dust, smoke, soot, sea salt, biological material and chemical reactions in the atmosphere. The fraction between 2.5 and 10 micrometres is often described as coarse particulate matter. PM2.5 is the finer portion contained within the PM10 measurement. ### Common sources of PM10 - Road and soil dust resuspended by traffic or wind - Construction, demolition, mining and material handling - Agriculture and natural dust events - Smoke and combustion emissions - Industrial operations and atmospheric particle formation ### Health effects Particles below 10 micrometres can be inhaled into the respiratory system. Exposure can aggravate respiratory symptoms, and particulate pollution is associated with effects on both the lungs and heart. Particle size is important, but composition and exposure duration also influence risk. A high PM10 reading should be interpreted with PM2.5 and local source information when available. ### WHO PM10 guideline values | Averaging period | WHO 2021 guideline | | --- | --- | | Annual mean | 15 µg/m³ | | 24-hour mean | 45 µg/m³ | ### Frequently asked questions Q: Does PM10 include PM2.5? A: Yes. PM2.5 is the fine-particle portion within the broader PM10 size category. Q: Can dust cause high PM10? A: Yes. Construction, roads, soil, mining, demolition and windblown dust can all contribute to PM10. Q: Is PM2.5 always more important than PM10? A: PM2.5 generally penetrates deeper and is especially important for health, but high PM10 can still create meaningful respiratory and environmental concerns. Sources: - WHO Global Air Quality Guidelines — World Health Organization (https://www.who.int/publications/i/item/9789240034228) - Particulate Matter (PM) Basics — United States Environmental Protection Agency (https://www.epa.gov/pm-pollution/particulate-matter-pm-basics) - Health and Environmental Effects of Particulate Matter — United States Environmental Protection Agency (https://www.epa.gov/pm-pollution/health-and-environmental-effects-particulate-matter-pm) Related: - https://aqi.news/pollutants/pm25 - https://aqi.news/learn/pm25-vs-pm10 - https://aqi.news/standards/india-air-quality-standards --- ## Ground-Level Ozone: Sources, Smog and Health Effects URL: https://aqi.news/pollutants/ozone Section: Pollutants Updated: 2026-07-27 Ground-level ozone is a reactive gas formed when nitrogen oxides and volatile organic compounds react in sunlight. Unlike protective stratospheric ozone, ozone near the ground is a harmful air pollutant and a major component of smog. Key facts: - Ground-level ozone is usually formed in the atmosphere rather than emitted directly. - Sunlight drives reactions between nitrogen oxides and volatile organic compounds. - Ozone can irritate and inflame airways and aggravate asthma. - WHO’s 2021 guideline includes 100 µg/m³ for the daily maximum 8-hour mean. ### “Good” ozone and “bad” ozone Ozone in the stratosphere helps shield Earth from harmful ultraviolet radiation. Ground-level, or tropospheric, ozone is different: it is breathed directly and can harm people, vegetation and ecosystems. ### How ground-level ozone forms Ozone forms through photochemical reactions involving nitrogen oxides and volatile organic compounds. Important precursor sources include vehicles, power plants, industrial boilers, refineries, solvents and other combustion or chemical activities. Warm, sunny and stagnant conditions often favor ozone formation, but ozone and its precursors can also travel, so elevated concentrations are not limited to a source’s immediate surroundings. ### Health effects and sensitive groups EPA states that ozone can cause coughing, throat irritation, difficulty breathing deeply, airway inflammation and worsening of diseases such as asthma. Children, older adults, people with asthma and people active outdoors are among the groups at greater risk. ### WHO ozone guideline values | Averaging period | WHO 2021 guideline | | --- | --- | | Daily maximum 8-hour mean | 100 µg/m³ | | Peak-season average | 60 µg/m³ | ### Frequently asked questions Q: Is ozone emitted directly by cars? A: Usually not. Vehicles emit precursor pollutants that can react in sunlight to form ozone. Q: Why can ozone be high on a sunny day? A: Sunlight accelerates the chemical reactions that form ground-level ozone from nitrogen oxides and volatile organic compounds. Q: Does the ozone layer cause city smog? A: No. Protective stratospheric ozone and harmful ground-level ozone occur in different parts of the atmosphere and have different consequences. Sources: - WHO Global Air Quality Guidelines — World Health Organization (https://www.who.int/publications/i/item/9789240034228) - Ground-level Ozone Basics — United States Environmental Protection Agency (https://www.epa.gov/ground-level-ozone-pollution/ground-level-ozone-basics) - Health Effects of Ozone Pollution — United States Environmental Protection Agency (https://www.epa.gov/ground-level-ozone-pollution/health-effects-ozone-pollution) Related: - https://aqi.news/learn/what-is-aqi - https://aqi.news/learn/aqi-scale - https://aqi.news/standards/who-air-quality-guidelines --- ## Nitrogen Dioxide (NO₂): Sources, Health Effects and AQI URL: https://aqi.news/pollutants/nitrogen-dioxide Section: Pollutants Updated: 2026-07-27 Nitrogen dioxide (NO₂) is a reactive gas produced mainly when fuels burn. Road traffic, power generation and combustion equipment are important sources, and short-term exposure can irritate airways and aggravate asthma. Key facts: - NO₂ is one of a group of reactive gases called nitrogen oxides. - Fuel combustion from vehicles, power plants and equipment is a major source. - NO₂ can irritate airways and worsen respiratory disease, especially asthma. - NO₂ also helps form ground-level ozone and particulate pollution. ### Where NO₂ comes from Nitrogen dioxide forms when fuel burns at high temperature. Outdoor sources include cars, trucks, buses, power plants and off-road equipment. Indoors, poorly vented gas appliances and other combustion sources can contribute. Traffic-related concentrations can vary sharply over short distances and by time of day, so a city-wide value may not represent every roadside location. ### Health and environmental effects Breathing elevated NO₂ for short periods can irritate the respiratory system. People with asthma, children and older adults may be more susceptible to coughing, wheezing or difficulty breathing. NO₂ and other nitrogen oxides participate in reactions that form ozone, particles, acid rain and haze. Reducing combustion emissions can therefore affect several pollutants at once. ### How to interpret an NO₂ reading - Check the unit: monitoring services commonly use parts per billion or micrograms per cubic metre. - Match the reading to the correct averaging period before comparing it with a guideline. - Use the pollutant sub-index, not concentration alone, when interpreting US AQI. - Treat a live reading as current information, not a formal compliance determination. ### Frequently asked questions Q: Is NO₂ the same as NOx? A: No. NOx is a broader group of nitrogen oxides. NO₂ is one member and is commonly used as an indicator for the group. Q: Can traffic raise NO₂? A: Yes. Cars, trucks and buses are important combustion sources, and concentrations can be higher near busy roads. Q: Does NO₂ create PM2.5? A: Nitrogen oxides can react in the atmosphere and contribute to nitrate particles, which can be part of PM2.5. Sources: - Basic Information about Nitrogen Dioxide — United States Environmental Protection Agency (https://www.epa.gov/no2-pollution/basic-information-about-no2) - WHO Global Air Quality Guidelines — World Health Organization (https://www.who.int/publications/i/item/9789240034228) Related: - https://aqi.news/pollutants/ozone - https://aqi.news/pollutants/pm25 - https://aqi.news/tools/aqi-calculator --- ## Sulfur Dioxide (SO₂): Sources, Health Effects and AQI URL: https://aqi.news/pollutants/sulfur-dioxide Section: Pollutants Updated: 2026-07-27 Sulfur dioxide (SO₂) is a reactive gas produced mainly by burning sulfur-containing fuels and by some industrial processes. Short-term exposure can make breathing difficult, particularly for people with asthma. Key facts: - Power plants and industrial fuel combustion are major SO₂ sources. - Metal extraction, ships, locomotives and volcanoes can also emit SO₂. - Short-term exposure can affect breathing, especially in people with asthma. - Sulfur oxides can form fine sulfate particles and contribute to acid rain. ### Where SO₂ comes from The largest human sources are fossil-fuel combustion at power plants and industrial facilities. Ore processing and high-sulfur fuels used by some ships, locomotives and heavy equipment can also contribute. SO₂ levels can be strongly influenced by nearby industrial sources, wind direction and atmospheric conditions. ### Health and environmental effects Short-term SO₂ exposure can harm the respiratory system and make breathing difficult. People with asthma, particularly children, can be more sensitive. Sulfur oxides can react with other compounds to form small particles, reduce visibility and contribute to acid deposition that harms ecosystems and materials. ### Reading SO₂ data correctly - Confirm whether the value is in parts per billion or micrograms per cubic metre. - Compare only with a limit that uses the same averaging period. - Check local source and wind information during short pollution spikes. - Use official monitoring procedures for regulatory decisions. ### Frequently asked questions Q: Can SO₂ become PM2.5? A: Sulfur oxides can react in the atmosphere and form fine sulfate particles that contribute to PM2.5. Q: Who is most sensitive to SO₂? A: People with asthma, especially children, are among the groups most sensitive to short-term respiratory effects. Q: Does AQI include SO₂? A: Yes. US and Indian AQI systems can calculate an SO₂ sub-index, though their breakpoints and averaging rules differ. Sources: - Sulfur Dioxide Basics — United States Environmental Protection Agency (https://www.epa.gov/so2-pollution/sulfur-dioxide-basics) - WHO Global Air Quality Guidelines — World Health Organization (https://www.who.int/publications/i/item/9789240034228) Related: - https://aqi.news/pollutants/pm25 - https://aqi.news/standards/who-air-quality-guidelines - https://aqi.news/tools/aqi-calculator --- ## Carbon Monoxide (CO): Sources, Symptoms and AQI URL: https://aqi.news/pollutants/carbon-monoxide Section: Pollutants Updated: 2026-07-27 Carbon monoxide (CO) is a colorless, odorless, toxic gas produced by incomplete combustion. High indoor concentrations can be immediately dangerous, while outdoor monitoring also uses CO as a criteria pollutant. Key facts: - CO cannot be seen, smelled or tasted. - Fuel-burning appliances, vehicles, generators and fires can produce CO. - Headache, dizziness, nausea, weakness and confusion can be warning symptoms. - Suspected CO poisoning is an emergency: move to fresh air and seek medical help. ### Common carbon monoxide sources Any fuel-fired appliance can produce CO, especially when it is incorrectly installed, poorly maintained or inadequately vented. Furnaces, heaters, stoves, fireplaces, generators and vehicles are common examples. Never operate a vehicle in a garage or a portable fuel-fired generator inside or close to a building. Outdoor AQI readings do not replace a working indoor CO alarm. ### Symptoms and immediate action - Headache, dizziness or nausea - Weakness, shortness of breath or confusion - Flu-like symptoms without fever - Loss of consciousness or death at high exposure Note: If a CO alarm sounds or poisoning is suspected, get everyone to fresh air immediately, contact emergency services and seek medical attention. Do not re-enter until authorities say it is safe. ### Preventing indoor CO exposure - Install and maintain CO alarms according to manufacturer instructions and local codes. - Have fuel-burning appliances, chimneys and vents inspected by qualified professionals. - Use generators, grills and other fuel-burning equipment only in safe outdoor locations. - Do not use an outdoor AQI value to judge whether indoor air is safe. ### Frequently asked questions Q: Can I smell carbon monoxide? A: No. CO is colorless and odorless, which is why working carbon monoxide alarms are important. Q: Will an air purifier remove CO? A: Typical particle filters do not remove carbon monoxide. Remove the source, ventilate only when safe, and follow emergency guidance. Q: Does an N95 protect against CO? A: No. An N95 filters particles; it does not supply oxygen or remove carbon monoxide gas. Sources: - Carbon Monoxide's Impact on Indoor Air Quality — United States Environmental Protection Agency (https://www.epa.gov/indoor-air-quality-iaq/carbon-monoxides-impact-indoor-air-quality) - WHO Global Air Quality Guidelines — World Health Organization (https://www.who.int/publications/i/item/9789240034228) Related: - https://aqi.news/tools/aqi-calculator - https://aqi.news/learn/what-is-aqi - https://aqi.news/respirators/reusable-respirators --- ## WHO Air Quality Guidelines: 2021 Pollutant Levels URL: https://aqi.news/standards/who-air-quality-guidelines Section: Standards and guidelines Updated: 2026-07-27 The WHO Global Air Quality Guidelines provide evidence-informed concentration levels designed to support protection of public health. They are recommendations rather than automatically binding legal standards. Key facts: - The current global guideline edition was published in 2021. - The guidelines cover PM2.5, PM10, ozone, nitrogen dioxide, sulfur dioxide and carbon monoxide. - WHO guideline values are health-based recommendations, not national legal limits. - Short-term and long-term values use different averaging periods. ### WHO 2021 guideline levels | Pollutant | Averaging period | Guideline level | | --- | --- | --- | | PM2.5 | Annual | 5 µg/m³ | | PM2.5 | 24-hour | 15 µg/m³ | | PM10 | Annual | 15 µg/m³ | | PM10 | 24-hour | 45 µg/m³ | | Ozone | Daily maximum 8-hour mean | 100 µg/m³ | | Ozone | Peak season | 60 µg/m³ | | Nitrogen dioxide | Annual | 10 µg/m³ | | Nitrogen dioxide | 24-hour | 25 µg/m³ | | Sulfur dioxide | 24-hour | 40 µg/m³ | | Carbon monoxide | 24-hour | 4 mg/m³ | ### Guideline values versus legal standards WHO guideline levels are designed as evidence-informed public-health references. Countries may use them when developing laws and policies, but national standards can differ because of legal frameworks, monitoring systems, feasibility and policy decisions. A concentration can comply with a national standard and still be above a WHO guideline. The correct comparison depends on the pollutant, unit and averaging period. ### Why averaging periods matter Annual means describe long-term exposure, while 24-hour and 8-hour values address shorter pollution episodes. Comparing a live hourly reading directly with an annual or 24-hour guideline is not a like-for-like compliance assessment. Note: AQI.news displays live and forecast-oriented data. Formal compliance with a standard requires the prescribed monitoring method, averaging period and data-completeness rules. ### Frequently asked questions Q: Are WHO guideline values legally binding? A: No. They are evidence-informed health recommendations. Governments decide whether and how to incorporate them into enforceable standards. Q: Can I compare a live PM2.5 reading with the annual guideline? A: Not directly. The annual guideline applies to a full-year mean, while a live value represents a much shorter period. Q: Why are Indian limits different from WHO guidelines? A: WHO publishes health-based recommendations, while India’s NAAQS are national regulatory standards established through India’s legal and policy process. Sources: - WHO Global Air Quality Guidelines — World Health Organization (https://www.who.int/publications/i/item/9789240034228) Related: - https://aqi.news/standards/india-air-quality-standards - https://aqi.news/pollutants/pm25 - https://aqi.news/pollutants/pm10 --- ## India Air Quality Standards and CPCB AQI Categories URL: https://aqi.news/standards/india-air-quality-standards Section: Standards and guidelines Updated: 2026-07-27 India uses National Ambient Air Quality Standards (NAAQS) for pollutant concentrations and a separate CPCB National AQI for daily public communication. These are related but not interchangeable systems. Key facts: - India’s CPCB AQI categories are Good, Satisfactory, Moderate, Poor, Very Poor and Severe. - India’s NAAQS specify pollutant concentrations and averaging periods. - AQI categories and NAAQS concentration standards serve different communication and regulatory purposes. - AQI.news labels its live headline readings as US AQI, not CPCB AQI. ### CPCB National AQI categories CPCB calculates pollutant sub-indices using India-specific concentration breakpoints. The worst qualifying sub-index determines the reported National AQI. | AQI | Category | | --- | --- | | 0–50 | Good | | 51–100 | Satisfactory | | 101–200 | Moderate | | 201–300 | Poor | | 301–400 | Very Poor | | 401–500 | Severe | ### Selected Indian NAAQS concentration limits | Pollutant | Annual limit | Short-term limit | | --- | --- | --- | | PM2.5 | 40 µg/m³ | 60 µg/m³ over 24 hours | | PM10 | 60 µg/m³ | 100 µg/m³ over 24 hours | | Nitrogen dioxide | 40 µg/m³ | 80 µg/m³ over 24 hours | | Sulfur dioxide | 50 µg/m³ | 80 µg/m³ over 24 hours | | Ozone | — | 100 µg/m³ over 8 hours; 180 µg/m³ over 1 hour | | Carbon monoxide | — | 2 mg/m³ over 8 hours; 4 mg/m³ over 1 hour | Note: The table summarizes standards for industrial, residential, rural and other areas. Ecologically sensitive areas have different annual limits for some gases. Consult the official CPCB standard for compliance work. ### Why AQI.news and CPCB can show different numbers AQI.news currently labels its headline city value as US AQI. CPCB uses India’s National AQI calculation. Different breakpoints alone can change the index, even before differences in station location, data source, averaging period and update time are considered. Use CPCB data and procedures for Indian regulatory or official reporting purposes. Use AQI.news as an informational view of live conditions and pollutant trends. ### Frequently asked questions Q: Does AQI.news display CPCB AQI? A: No. The current headline city index is explicitly labelled US AQI. CPCB’s National AQI uses different breakpoints and category names. Q: Is India’s PM2.5 annual standard 40 µg/m³? A: Yes. India’s NAAQS lists an annual PM2.5 limit of 40 µg/m³ and a 24-hour limit of 60 µg/m³. Q: Are WHO guidelines and Indian NAAQS the same? A: No. WHO guidelines are global health-based recommendations. India’s NAAQS are national standards with different concentration values and compliance rules. Sources: - National Air Quality Index — Central Pollution Control Board, India (https://www.cpcb.gov.in/displaypdf.php?id=bmF0aW9uYWwtYWlyLXF1YWxpdHktaW5kZXgvQWJvdXRfQVFJLnBkZg%3D%3D) - National Ambient Air Quality Standards — Central Pollution Control Board, India (https://cpcb.gov.in/upload/NAAQS_2019.pdf) Related: - https://aqi.news/standards/who-air-quality-guidelines - https://aqi.news/learn/what-is-aqi - https://aqi.news/learn/aqi-scale --- ## Construction Dust: Sources, Risks and Exposure Controls URL: https://aqi.news/dust/construction-dust Section: Occupational dust and fumes Updated: 2026-07-27 Cutting, grinding, drilling, demolition and material handling can release inhalable and respirable dust. Effective control starts at the source with substitution, wet methods, extraction and isolation. Key facts: - Construction dust can contain respirable crystalline silica and other hazardous materials. - Wet methods and local exhaust can prevent dust becoming airborne. - Dry sweeping and uncontrolled cutting can create avoidable exposure. - Respirators supplement controls and must be selected for the assessed hazard. ### Tasks that can generate dust - Cutting, grinding or drilling concrete, brick, mortar, stone and tile - Demolition and abrasive blasting - Mixing dry powders and emptying bags - Sweeping, compressed-air cleaning and debris handling ### Control dust at the source Use lower-dust materials or methods where feasible, then apply engineering controls such as water delivery, on-tool extraction, local exhaust and enclosure. Restrict access and use suitable dust-class vacuums or wet cleanup methods. Control performance depends on the tool, task, material and maintenance. Employers should assess exposure and follow applicable local requirements. ### Where respirators fit Respirators may be required when source controls cannot adequately reduce exposure or while controls are being installed. The selected device must match the contaminant and exposure level and must be used in a respiratory-protection program when required at work. Note: A disposable dust mask is not a substitute for wet cutting, extraction, isolation or an exposure assessment. ### Frequently asked questions Q: Is all construction dust silica? A: No. Construction dust is a mixture. Concrete, brick, mortar, stone and similar materials may release respirable crystalline silica when disturbed. Q: Should construction dust be dry swept? A: Dry sweeping can put settled dust back into the air. Use a suitable vacuum or wet cleanup method where required and feasible. Q: Is an N95 always enough? A: No. Required protection depends on the hazard, concentration, task and local rules. Some work requires higher protection or supplied air. Sources: - Crystalline Silica Exposure in the Construction Industry — Occupational Safety and Health Administration (https://www.osha.gov/training/library/silica/construction) - Crystalline Silica: Health Effects — Occupational Safety and Health Administration (https://www.osha.gov/silica-crystalline/health-effects) Related: - https://aqi.news/dust/silica-dust - https://aqi.news/dust/cement-dust - https://aqi.news/respirators/n95 --- ## Cement Dust: Health Effects and Workplace Controls URL: https://aqi.news/dust/cement-dust Section: Occupational dust and fumes Updated: 2026-07-27 Dry Portland cement is an irritating powder that can affect the eyes, skin and respiratory system. The risk changes with composition, task and the presence of respirable crystalline silica. Key facts: - Portland cement can irritate the eyes, skin, nose and respiratory system. - Cough, wheezing, breathing difficulty and dermatitis are recognized concerns. - Cement products may also create a silica hazard when cut, ground or otherwise disturbed. - Prevent skin and eye contact as well as inhalation. ### How exposure happens Opening bags, mixing dry cement, transferring powder and cleaning spills can release dust. Cutting or grinding hardened cement products can create a different particle mixture and may release respirable crystalline silica. ### Practical controls - Use enclosed transfer, local exhaust or lower-dust delivery methods. - Add dry material carefully and avoid throwing or dropping powder. - Use suitable vacuum or wet cleanup rather than dry sweeping. - Provide appropriate eye, skin and respiratory protection for the task. ### Respirator selection NIOSH recommendations vary with measured concentration and the material present. A hazard assessment should identify whether the concern is Portland cement particulate, crystalline silica or another additive before selecting protection. ### Frequently asked questions Q: Can cement dust irritate skin? A: Yes. Cement can cause irritation and dermatitis; wet cement also presents important skin hazards. Q: Does cement contain silica? A: Composition varies. Cutting or grinding concrete and cement-based products can release respirable crystalline silica and requires task-specific controls. Q: Can I use an ordinary face covering? A: An ordinary face covering is not workplace respiratory protection. Use the device selected through the applicable hazard assessment and program. Sources: - NIOSH Pocket Guide: Portland Cement — National Institute for Occupational Safety and Health (https://www.cdc.gov/niosh/npg/npgd0521.html) - Crystalline Silica: Health Effects — Occupational Safety and Health Administration (https://www.osha.gov/silica-crystalline/health-effects) Related: - https://aqi.news/dust/construction-dust - https://aqi.news/dust/silica-dust - https://aqi.news/respirators/p100 --- ## Textile Dust: Cotton Dust, Lung Risks and Controls URL: https://aqi.news/dust/textile-dust Section: Occupational dust and fumes Updated: 2026-07-27 Textile work can expose people to cotton dust, fibres and biological contaminants. Cotton-dust exposure is associated with byssinosis and long-term loss of lung function, making source control and exposure monitoring important. Key facts: - Cotton dust exposure can cause byssinosis, an airways disease with asthma- and COPD-like features. - Endotoxin in organic dust can contribute to respiratory effects. - Enclosure, ventilation, housekeeping and process controls come before respirators. - Workplace limits and required programs vary by operation and jurisdiction. ### Where textile dust exposure occurs Opening, carding, spinning, weaving, waste handling and cleaning can release cotton and other organic dusts. Fibre type, processing stage, ventilation and housekeeping all influence exposure. ### Respiratory concerns Byssinosis can involve chest tightness, cough, wheeze and airflow limitation. NIOSH-supported research also links long-term endotoxin exposure among cotton workers with accelerated lung-function decline. Symptoms should be assessed by occupational-health professionals; absence of visible dust does not confirm that exposure is controlled. ### Reducing exposure - Enclose dusty processes and capture emissions with local exhaust. - Maintain equipment and ventilation to prevent dust escape. - Use vacuum cleaning methods designed for the material. - Monitor exposure and provide health surveillance where required. ### Frequently asked questions Q: What is byssinosis? A: Byssinosis is an airways disease associated with cotton-dust exposure and can have features resembling asthma and COPD. Q: Is textile dust only loose fibre? A: No. It can include fibres, fine particles, dyes, finishes and biological material such as endotoxin, depending on the process. Q: Which respirator should textile workers use? A: Selection must follow the measured hazard, task and applicable workplace program; a filter class cannot be chosen safely from the industry name alone. Sources: - Lung Disease in Textile Workers — National Institute for Occupational Safety and Health (https://www.cdc.gov/niosh/bulletin/2021/textiles.html) - Respirator Selection and Use — National Institute for Occupational Safety and Health (https://www.cdc.gov/niosh/ppe/respirators/selection.html) Related: - https://aqi.news/respirators/n95 - https://aqi.news/respirators/reusable-respirators - https://aqi.news/dust/construction-dust --- ## Mining Dust: Respiratory Risks and Dust Controls URL: https://aqi.news/dust/mining-dust Section: Occupational dust and fumes Updated: 2026-07-27 Mining and mineral processing can release respirable coal, silica and other mineral dusts. Repeated exposure can cause disabling lung disease, so operations commonly need several engineering and administrative controls working together. Key facts: - Respirable coal mine dust can cause coal workers’ pneumoconiosis, or black lung. - Respirable silica can cause silicosis and other serious disease. - Ventilation, water sprays, enclosed cabs and dust capture are common controls. - Dust sampling is necessary to verify that controls work. ### The dust is not all the same Coal, stone, ore and surrounding rock produce different particle mixtures. Drilling, cutting, crushing, conveying and vehicle movement can generate respirable dust that reaches deep into the lungs. A task may involve coal dust, crystalline silica, diesel particulate and other contaminants at the same time. ### Dust-control methods - Ventilation that carries contaminants away from workers - Water sprays and wet drilling or cutting - Enclosures, local exhaust and sealed operator cabs - Maintenance, housekeeping and real-time or personal dust monitoring ### Respiratory protection Respirators may be part of the control plan, particularly during specific tasks or maintenance, but they do not replace feasible engineering controls. Selection requires the contaminant, exposure concentration and work conditions. ### Frequently asked questions Q: What is black lung? A: Black lung is coal workers’ pneumoconiosis, a potentially disabling disease caused by inhaling respirable coal mine dust. Q: Can mining dust contain silica? A: Yes. Cutting or drilling rock can release respirable crystalline silica even in coal-mining operations. Q: Why is dust monitoring important? A: Dust may be invisible at harmful respirable sizes, and monitoring is needed to measure exposure and confirm whether controls are effective. Sources: - Best Practices for Dust Control in Coal Mining — National Institute for Occupational Safety and Health (https://www.cdc.gov/niosh/docs/2021-119/default.html) - Crystalline Silica: Health Effects — Occupational Safety and Health Administration (https://www.osha.gov/silica-crystalline/health-effects) Related: - https://aqi.news/dust/silica-dust - https://aqi.news/respirators/p100 - https://aqi.news/respirators/reusable-respirators --- ## Welding Fumes: Hazards, Ventilation and Respirators URL: https://aqi.news/dust/welding-fumes Section: Occupational dust and fumes Updated: 2026-07-27 Welding fumes are a complex mixture of very small particles, metal oxides and gases generated by the process, base metal, coatings, electrode and flux. Hazard and control requirements vary substantially by job. Key facts: - Welding fume composition changes with the metal, coating, electrode and process. - Possible effects include irritation, cough, breathing difficulty and metal fume fever. - Stainless, coated and specialty metals can introduce particularly hazardous constituents. - Local exhaust should capture fume close to where it is generated. ### What is in welding fume? The plume can contain metals and metal oxides from the workpiece, filler and coatings, plus process gases. Stainless steel, galvanized metal, painted surfaces and confined spaces require special attention. Because composition varies, “welding fume” is not one substance with one universally suitable filter. ### Control the plume - Substitute lower-hazard processes or consumables where feasible. - Use local exhaust positioned close enough to capture the plume. - Keep the welder’s breathing zone out of the fume path. - Remove hazardous coatings safely and provide general ventilation. ### Selecting respiratory protection Particle filters do not remove gases and vapours. The correct respirator can require particulate filters, chemical cartridges, supplied air or a combination, depending on the assessment. Confined or oxygen-deficient spaces require specialist procedures and cannot be made safe by an ordinary filtering respirator. ### Frequently asked questions Q: Is welding smoke only metal dust? A: No. Welding can generate very fine metal-containing particles and gases; exact composition depends on the job. Q: Does an N95 remove welding gases? A: No. N95 filters are for particles and do not remove gases or vapours. Q: Where should local exhaust be placed? A: It should capture the plume close to its source without disrupting the process; placement and airflow should be verified for the specific job. Sources: - NIOSH Pocket Guide: Welding Fumes — National Institute for Occupational Safety and Health (https://www.cdc.gov/niosh/npg/npgd0666.html) - Welding Operations: Local Exhaust Ventilation Systems — National Institute for Occupational Safety and Health (https://www.cdc.gov/niosh/engcontrols/ecd/detail44.html) Related: - https://aqi.news/respirators/reusable-respirators - https://aqi.news/respirators/p100 - https://aqi.news/dust/construction-dust --- ## Silica Dust: Health Risks, High-Exposure Tasks and Controls URL: https://aqi.news/dust/silica-dust Section: Occupational dust and fumes Updated: 2026-07-27 Respirable crystalline silica is created when silica-containing stone, concrete, brick, mortar and similar materials are cut, ground, drilled or crushed. Inhalation can cause irreversible and potentially fatal disease. Key facts: - Respirable crystalline silica particles are small enough to reach deep lung tissue. - Exposure can cause silicosis, lung cancer, COPD and kidney disease. - Silicosis has no cure, making prevention essential. - Wet methods, local exhaust and isolation are primary controls. ### Work that can release silica - Cutting, sawing, grinding or drilling concrete and masonry - Stone countertop fabrication and installation - Abrasive blasting with silica-containing material - Mining, crushing, tunnelling and demolition ### Health effects Silica dust can cause scar tissue in the lungs, reducing their ability to take in oxygen. Disease can develop after years of exposure, while very high exposures can cause accelerated or acute silicosis. Workers may not notice early symptoms. Medical surveillance and occupational-health assessment are important where regulations require them. ### Preventing exposure - Use water-fed tools or local exhaust designed for the task. - Isolate dusty work and limit access. - Avoid dry sweeping and compressed-air cleanup where prohibited. - Verify controls with exposure monitoring and maintain them. Note: Respirator requirements depend on the task, exposure and applicable regulation. Follow the task-specific control table or occupational-safety authority for your location. ### Frequently asked questions Q: Can silica dust be seen? A: The respirable fraction can be too small to see. Visible dust is a warning, but no visible cloud does not prove the air is safe. Q: Is silicosis curable? A: No. OSHA describes silicosis as an incurable lung disease, so preventing exposure is essential. Q: Does wet cutting eliminate all risk? A: Wet methods can greatly reduce airborne dust but must be correctly designed, supplied and maintained; additional controls may still be required. Sources: - Crystalline Silica: Health Effects — Occupational Safety and Health Administration (https://www.osha.gov/silica-crystalline/health-effects) - Crystalline Silica Exposure in the Construction Industry — Occupational Safety and Health Administration (https://www.osha.gov/training/library/silica/construction) Related: - https://aqi.news/dust/construction-dust - https://aqi.news/dust/mining-dust - https://aqi.news/respirators/p100 --- ## N95 Respirators: Filtration, Fit and Correct Use URL: https://aqi.news/respirators/n95 Section: Respirator guides Updated: 2026-07-27 A NIOSH-approved N95 filtering facepiece respirator filters at least 95% of the certification test aerosol and is not resistant to oil. Real-world protection also depends on selection, fit, seal, condition and correct use. Key facts: - N means the filter is not resistant to oil. - 95 means at least 95% filtration in the NIOSH certification test. - A tight face seal is essential; facial hair can interfere with it. - N95 respirators do not remove gases, vapours or carbon monoxide. ### What the N95 rating means N95 is a U.S. NIOSH filter class. Approved products carry required markings including NIOSH, the filter class and a TC approval number that can be checked in the Certified Equipment List. The rating describes laboratory filter performance, not a guarantee that every wearer receives the same protection. ### Fit and use - Choose an approved model and the correct size and style. - Inspect it before use and discard it if damaged, dirty or damp. - Put it on with clean, dry hands and perform a seal check every time. - Use workplace fit testing and medical evaluation when required. ### Important limitations N95s filter particles; they do not supply oxygen or protect against gases and vapours. They are unsuitable for unknown, immediately dangerous or oxygen-deficient atmospheres. ### Frequently asked questions Q: Does an N95 help with PM2.5? A: A genuine, well-fitted N95 can reduce inhalation of airborne particles, including particles in the PM2.5 size range, but fit and correct use are critical. Q: Is N95 the same as a surgical mask? A: No. An N95 is designed to seal to the face and meet a respirator standard; an ordinary surgical mask is not a tight-fitting respirator. Q: Can an N95 protect against carbon monoxide? A: No. Carbon monoxide is a gas and is not removed by an N95 particle filter. Sources: - Filtering Facepiece Respirators — National Institute for Occupational Safety and Health (https://www.cdc.gov/niosh/ppe/respirators/ffr.html) - Respirator Selection and Use — National Institute for Occupational Safety and Health (https://www.cdc.gov/niosh/ppe/respirators/selection.html) Related: - https://aqi.news/respirators/n99 - https://aqi.news/respirators/ffp2 - https://aqi.news/pollutants/pm25 --- ## N99 Respirators: Higher Filtration and Practical Limits URL: https://aqi.news/respirators/n99 Section: Respirator guides Updated: 2026-07-27 A NIOSH-approved N99 filter captures at least 99% of the certification test aerosol and is not resistant to oil. Higher filter efficiency does not compensate for a poor seal or incorrect hazard selection. Key facts: - N99 filters at least 99% of the certification test aerosol. - N-series filters are not resistant to oil. - Fit and seal remain as important as filter efficiency. - N99 filters do not remove gases or vapours. ### N99 versus N95 The efficiency number refers to standardized certification testing. The protection actually achieved by a wearer is also limited by face-seal leakage, condition and use. | Class | Minimum test efficiency | Oil resistance | | --- | --- | --- | | N95 | 95% | Not resistant to oil | | N99 | 99% | Not resistant to oil | ### When higher efficiency helps A hazard assessment may call for a higher-efficiency filter, but breathing resistance, comfort, communication and fit also affect whether the device can be used correctly for the full task. ### Limits - Not for oil aerosols - Not for gases, vapours or carbon monoxide - Not for oxygen-deficient or unknown atmospheres - Not a substitute for source control ### Frequently asked questions Q: Is N99 always better than N95? A: It has higher test filtration, but the best respirator is the approved model that matches the hazard, fits the wearer and can be used correctly. Q: Does N99 require fit testing? A: Tight-fitting workplace respirators require fit testing where mandated by the respiratory-protection program. Q: Can N99 be used around oil mist? A: N-series filters are not resistant to oil. A qualified assessment should select an appropriate R- or P-series filter where oil aerosols are present. Sources: - Filtering Facepiece Respirators — National Institute for Occupational Safety and Health (https://www.cdc.gov/niosh/ppe/respirators/ffr.html) - Respirator Selection and Use — National Institute for Occupational Safety and Health (https://www.cdc.gov/niosh/ppe/respirators/selection.html) Related: - https://aqi.news/respirators/n95 - https://aqi.news/respirators/p100 - https://aqi.news/respirators/reusable-respirators --- ## FFP2 Respirators: European Rating, Fit and Limitations URL: https://aqi.news/respirators/ffp2 Section: Respirator guides Updated: 2026-07-27 FFP2 is a European filtering-facepiece class under EN 149. It is often discussed alongside N95, but the standards use different test methods and markings, so the labels are not interchangeable certifications. Key facts: - FFP2 is a European filtering-facepiece classification. - A tight seal to the face is necessary for expected protection. - Certification markings should match the market and applicable standard. - Particle-filtering facepieces do not protect against gases or oxygen deficiency. ### Understanding the classification FFP2 products are certified under European requirements, while N95 is a NIOSH class. Their performance goals are broadly comparable for many particle applications, but test conditions, approval systems and markings differ. Buy through a trustworthy supplier and check the required product, standard and conformity markings for your jurisdiction. ### Fit is part of protection Filtering facepieces rely on a seal so inhaled air passes through the filter material. Wearer fit testing, a pre-use seal check and a clean-shaven seal area are important for tight-fitting workplace RPE. ### Limitations - Not a gas or vapour filter - Does not supply oxygen - Cannot make an unknown atmosphere safe - Must match the task and local workplace requirements ### Frequently asked questions Q: Is FFP2 exactly the same as N95? A: No. They are certifications under different systems with different test requirements, even though they are often used for similar particle hazards. Q: Does an FFP2 need to seal? A: Yes. Leakage around the face can substantially reduce protection from any tight-fitting filtering facepiece. Q: Does FFP2 remove gases? A: No. A standard FFP2 filters particles and does not remove gases or vapours. Sources: - Types of Respiratory Protective Equipment — UK Health and Safety Executive (https://www.hse.gov.uk/respiratory-protective-equipment/types-rpe.htm) - Respirator Fit Testing Basics — UK Health and Safety Executive (https://www.hse.gov.uk/respiratory-protective-equipment/fit-testing-basics.htm) - Respirator Selection and Use — National Institute for Occupational Safety and Health (https://www.cdc.gov/niosh/ppe/respirators/selection.html) Related: - https://aqi.news/respirators/n95 - https://aqi.news/respirators/ffp3 - https://aqi.news/pollutants/pm25 --- ## FFP3 Respirators: Higher Particle Protection and Fit URL: https://aqi.news/respirators/ffp3 Section: Respirator guides Updated: 2026-07-27 FFP3 is the highest filtering-facepiece class in EN 149. It offers higher tested particle filtration than FFP2, but correct selection, fit testing and source controls remain essential. Key facts: - FFP3 is a European particle-filtering facepiece class. - Higher filter performance does not correct face-seal leakage. - Tight-fitting RPE must be suitable for the wearer and task. - FFP3 does not remove gases or provide oxygen. ### FFP3 versus FFP2 FFP3 has more stringent particle-filtration and inward-leakage requirements than FFP2 under the European standard. The required class should come from a competent hazard assessment rather than a general preference for the highest label. ### Fit and sustained use - Select a model that passes an appropriate fit test for the wearer. - Perform a seal check each time the respirator is put on. - Check compatibility with eye, hearing and head protection. - Replace or maintain the device according to its instructions. ### What FFP3 does not do FFP3 is a particle class. It does not protect against gases, vapours, carbon monoxide or oxygen deficiency, and it does not replace enclosure, extraction, ventilation or wet methods. ### Frequently asked questions Q: Is FFP3 better than FFP2? A: FFP3 has higher tested particle protection, but suitability depends on the hazard, fit, wearer and task. Q: Can facial hair affect FFP3 protection? A: Yes. Hair in the seal area can prevent a tight-fitting facepiece from sealing correctly. Q: Can FFP3 be used for welding gases? A: A particle-filtering facepiece does not remove gases. Welding protection must be selected for the complete fume and gas mixture. Sources: - Types of Respiratory Protective Equipment — UK Health and Safety Executive (https://www.hse.gov.uk/respiratory-protective-equipment/types-rpe.htm) - Respirator Fit Testing Basics — UK Health and Safety Executive (https://www.hse.gov.uk/respiratory-protective-equipment/fit-testing-basics.htm) - Respirator Selection and Use — National Institute for Occupational Safety and Health (https://www.cdc.gov/niosh/ppe/respirators/selection.html) Related: - https://aqi.news/respirators/ffp2 - https://aqi.news/respirators/p100 - https://aqi.news/dust/silica-dust --- ## P100 Respirators: Filtration, Oil Resistance and Use URL: https://aqi.news/respirators/p100 Section: Respirator guides Updated: 2026-07-27 A NIOSH P100 filter captures at least 99.97% of the certification test aerosol and is strongly resistant to oil. P100 describes particle filtration only; it does not by itself protect against gases or vapours. Key facts: - P means strongly resistant to oil. - 100 means at least 99.97% filtration in the NIOSH test. - P100 filters may be used on filtering facepieces or reusable respirators. - A P100 particle filter alone does not remove gases or vapours. ### What P100 means | Feature | Meaning | | --- | --- | | P | Strongly resistant to oil aerosols | | 100 | At least 99.97% efficiency in the certification test | | Approval | Look for NIOSH markings and a valid approval configuration | ### Selecting P100 protection A qualified assessment may select P100 for high-efficiency particle filtration or work involving oil aerosols. The facepiece type and assigned protection factor matter in addition to the filter class. When cartridges combine P100 media with gas or vapour protection, the complete NIOSH-approved configuration and cartridge change schedule must be followed. ### Important limits - Does not supply oxygen - Particle-only P100 filters do not remove gases or vapours - Requires a correct seal on tight-fitting facepieces - Cannot substitute for feasible engineering controls ### Frequently asked questions Q: Is P100 better than N95? A: P100 has higher test efficiency and oil resistance, but the correct choice depends on the assessed hazard, facepiece and fit. Q: Does P100 filter welding fumes? A: It can filter particles in welding fume when used in an approved, suitable configuration, but it does not remove welding gases. Q: Does P100 protect against carbon monoxide? A: No. A P100 particle filter does not remove carbon monoxide and does not supply breathable air. Sources: - Filtering Facepiece Respirators — National Institute for Occupational Safety and Health (https://www.cdc.gov/niosh/ppe/respirators/ffr.html) - Respirator Selection and Use — National Institute for Occupational Safety and Health (https://www.cdc.gov/niosh/ppe/respirators/selection.html) Related: - https://aqi.news/respirators/n99 - https://aqi.news/respirators/reusable-respirators - https://aqi.news/dust/silica-dust --- ## Reusable Respirators: Filters, Cartridges and Maintenance URL: https://aqi.news/respirators/reusable-respirators Section: Respirator guides Updated: 2026-07-27 Reusable elastomeric respirators use replaceable filters, cartridges or canisters selected for specific particles, gases or vapours. The facepiece must fit, and the complete device requires cleaning, inspection, storage and scheduled filter changes. Key facts: - Reusable respirators can protect against particles, gases or vapours only with the correct approved filter or cartridge. - Half-mask and full-face models must form a seal and require fit testing. - Cartridges have a limited service life and require a change schedule. - Air-purifying respirators are not suitable for oxygen-deficient atmospheres. ### Facepiece and filter types | Component | Purpose | | --- | --- | | Half-mask facepiece | Seals over the nose and mouth. | | Full-face facepiece | Seals around the face and also covers the eyes. | | Particle filter | Captures selected airborne particles, not gases. | | Gas/vapour cartridge | Targets listed chemicals within approved conditions. | | Combination cartridge | Combines specified particle and chemical protection. | ### Selection requires hazard information Identify the contaminant, concentration, physical form, exposure limit and work conditions. Select the complete approved assembly rather than mixing unapproved facepieces, filters or cartridges. Air-purifying devices cannot be used where the contaminant is unknown, conditions are immediately dangerous, or oxygen is deficient. ### Fit, cleaning and replacement - Fit test each tight-fitting model and size used at work. - Inspect valves, straps, seals and filter connections before use. - Clean, disinfect, dry and store the facepiece as instructed. - Use an evidence-based cartridge change schedule; do not wait to smell breakthrough. ### Frequently asked questions Q: Are reusable respirators better than disposable ones? A: They can offer broader configurations and repeated use, but require more selection, cleaning, maintenance and storage. Suitability depends on the hazard and program. Q: Can any cartridge fit any facepiece? A: No. Use only components listed in the respirator’s approved configuration and manufacturer instructions. Q: When should a gas cartridge be changed? A: Use a documented change schedule based on objective information and the manufacturer or program requirements, before the end of service life. Sources: - Elastomeric Respirators — National Institute for Occupational Safety and Health (https://www.cdc.gov/niosh/ppe/respirators/elastomeric.html) - Respirator Selection and Use — National Institute for Occupational Safety and Health (https://www.cdc.gov/niosh/ppe/respirators/selection.html) - Types of Respiratory Protective Equipment — UK Health and Safety Executive (https://www.hse.gov.uk/respiratory-protective-equipment/types-rpe.htm) Related: - https://aqi.news/respirators/p100 - https://aqi.news/respirators/n95 - https://aqi.news/dust/welding-fumes --- # Articles ## The Air Your Children Are Breathing: What Parents in Indian Cities Need to Know URL: https://aqi.news/blogs/air-pollution-children-india-parents-guide Published: 2026-08-04 Author: AQI.news Editorial Team Children breathe roughly 50% more air per kilogram of body weight than adults, and their lungs are still forming. In a city where the AQI regularly crosses 200, that is a daily calculation every parent is making — whether they realize it or not. Children breathe approximately 50% more air per unit of body weight than adults do. Their respiratory and immune systems are still developing. Their lungs are growing. In a city where the AQI regularly exceeds 200, those are not abstract facts – they are a daily calculation every parent is making, whether they realize it or not. The conversation about air pollution and health in India is often framed around adults – commuters, outdoor workers, the elderly. Children are discussed less, perhaps because the harms are harder to see in the short term. A child who has grown up breathing polluted air does not know what clean air feels like. There is no before-and-after comparison for them to notice. But the research is unambiguous: early childhood exposure to particulate matter has lasting effects on lung development, cognitive function, and long-term health outcomes. ### Why Children Are More Vulnerable Three biological factors make children disproportionately susceptible to air pollution: - Their breathing rate is higher. A child at rest breathes more air per kilogram of body weight than an adult, so every hour spent outdoors on a high-AQI day means inhaling more pollutants relative to body size. - Their lungs are still forming. The critical window of lung development runs from birth through adolescence. Chronic exposure to fine particulate matter during this window has been linked to reduced lung capacity — a deficit that does not necessarily reverse when the exposure ends. - Their immune and detoxification systems are less developed. Adults have more mature mechanisms for neutralising the oxidative stress that pollutants trigger in lung tissue. Children absorb the damage more directly. ### What the Research Indicates Multiple longitudinal studies in China, Europe, the US, and increasingly in South Asian contexts point the same way. Children in high-pollution areas show lower lung function scores, higher rates of asthma and respiratory infections, and — in several studies — measurably lower cognitive test scores compared with peers in cleaner areas. The cognitive angle deserves particular attention. A review of studies across multiple countries found that PM2.5 and NO₂ exposure in early childhood was associated with reduced verbal and non-verbal intelligence scores. The researchers framed pollution not just as a health hazard but as an equity issue: children in poorer, more polluted neighbourhoods face an environmental cognitive disadvantage on top of their socioeconomic ones. In Indian cities, where the poorest families often live near industrial areas, arterial roads, or open burning sites, that compound vulnerability is very real. ### The School Day Problem The average Indian child spends six to eight hours at school. Many schools have playgrounds facing major roads or sit in areas with high traffic density. Outdoor PT classes, sports periods, and the commute itself are all periods of heightened exposure — and precisely the activities that produce deep, rapid breathing, maximising pollutant intake. Some schools in Delhi and other high-AQI cities have introduced air purifiers in classrooms, and a few have made real-time AQI monitoring part of their outdoor activity policy. These are the right instincts. But adoption is still patchy and largely driven by individual school decisions rather than systemic policy. ### Practical Guidance for Parents Awareness without action is frustrating. Here are evidence-aligned steps parents can take: - Check the AQI before school drop-off. If the real-time reading at your location exceeds 150, reconsider extended outdoor activity for the day. The good window in most Indian cities is early morning, before traffic peaks. - Invest in indoor filtration. A HEPA air purifier running overnight in a child’s bedroom cuts cumulative exposure across the 8–10 hours spent sleeping — a significant share of total daily exposure time. - Teach children to notice the air. Children who understand that hazy skies and burning eyes are signals worth paying attention to grow into adults who make better exposure decisions. The AQI dashboard is not just for adults. - Advocate for school-level policy. Parent-teacher associations can raise the question of real-time AQI monitoring and outdoor activity thresholds. Starting that conversation costs nothing. ### The Long View There is a statistic worth sitting with: the generation of children born in Delhi NCR over the last decade will, on average, have spent more time breathing air above the WHO annual PM2.5 guideline than any previous generation — unless something changes structurally. That is not a reason for despair. It is a reason to track, to advocate, to make different individual decisions, and to expect more from urban policy. The dashboard tells you what today’s air looks like. What comes next is a decision. --- ## The Cities That Breathed Again: Clean Air Success Stories From Around the World URL: https://aqi.news/blogs/cities-that-cleaned-their-air Published: 2026-07-28 Author: AQI.news Editorial Team Ten years ago, you couldn't see the mountains from Beijing's city center. Today, on many days, you can. That's not a metaphor. It's measured, documented, and replicable. It's one of the most under-told environmental stories of our time. We spend a lot of time talking about how bad the air is. Rightfully so! Roughly 7 million people die from air pollution-related causes every year, and hundreds of millions more live with chronic respiratory compromise. The data is grim, and ignoring it helps no one. But here's what doesn't get enough space: the data is also full of hope. Several cities across the world have made measurable, significant progress on air quality over the past two decades. Not through magic. Not through economic collapse. Through policy, technology, investment, and repeatedly stubborn political will. These are their stories. ### Beijing: The Long Game In 2013, Beijing recorded average PM2.5 concentrations above 85 micrograms per cubic meter which is roughly 8x the WHO's recommended annual guideline. Images of residents wearing respirators while commuting went viral worldwide. The government, facing enormous public pressure, launched one of the most ambitious clean air action plans in history. What followed was a decade of unglamorous, grinding reform: coal plants within the city limits were shut down or converted to natural gas, heavy-polluting vehicles were phased out through a tiered license plate system, hundreds of industrial facilities were relocated or closed, and a nationwide real-time air monitoring network was built from scratch. By the early 2020s, Beijing's average annual PM2.5 had dropped by nearly 55%. The mountains reappeared. The city still has bad days. Air quality doesn't transform overnight, but the trend line is unmistakably downward. More importantly, it proved that even a megacity of 20+ million people can course-correct. The lesson isn't that Beijing's model should be copied wholesale. It's that sustained political commitment, matched by measurement and transparency, moves the needle. ### London: From Pea-Soup to Breathable London's Great Smog of 1952 killed an estimated 4,000 people in four days. The event was so catastrophic that it directly led to the UK's Clean Air Act of 1956 - one of the world's first major pieces of air pollution legislation. Seventy years later, London is still working on it, but the progress is real. The city's Ultra Low Emission Zone (ULEZ), which charges highly polluting vehicles for entering the central city, has dramatically reduced roadside nitrogen dioxide. Newer expansions of the zone have extended these benefits to outer boroughs. London's story is a useful counter-narrative to the idea that economic activity and clean air are opposites. The ULEZ was controversial. Businesses protested. Some residents pushed back. But the measurements since its introduction show consistent improvements in NO₂ levels along major roads. Also, the city's long-term air quality trend has been one of steady improvement since peak industrial-era pollution. ### Bogotá: The Unlikely Turnaround South America's air quality doesn't often make global headlines, but Bogotá's transformation deserves recognition. Colombia's capital once struggled with severe vehicle emissions and industrial pollution. Over the past 15 years, the city has expanded its TransMilenio Bus Rapid Transit system, deployed electric buses, and invested heavily in cycling infrastructure - not just for commuters, but as a culture shift. Bogotá now has one of the most extensive cycling networks in South America. On Sundays, major arterial roads are closed to motor vehicles and given over to cyclists and pedestrians in an event called Ciclovía; a tradition that has been running since 1974 and attracts millions of participants each year. Air quality improvements in Bogotá are harder to isolate from broader urban changes, but the directional story is positive. More importantly, the city demonstrates that mobility reform is not just industrial control but is a legitimate lever for cleaner air. ### Delhi NCR: Early Signs of Progress It would be dishonest to call Delhi's air quality a success story yet. But it would also be inaccurate to ignore what's changed. The phased retirement of older, high-polluting vehicles, the expansion of the Delhi Metro network to over 390 km, the introduction of BS-VI fuel emission standards across India, and real-time AQI monitoring infrastructure across the NCR have all moved conditions in the right direction. On specific metrics like vehicle emissions, some industrial parameters - Delhi is better than it was a decade ago. The challenge is that population growth, crop burning cycles, construction activity, and seasonal meteorology continue to push back against these gains. Progress exists. It's just not yet winning. ### What These Cities Have in Common Every city that has meaningfully improved its air quality shares a few traits: they built measurement infrastructure first, so they could track what worked; they treated transport as a primary lever alongside industry; they didn't wait for perfect conditions before acting; and they communicated the data to residents. That last point matters more than it sounds. When people can see their city's air quality in real-time and not as an abstract annual average, but as a live number tied to where they live and breathe, something shifts. They ask better questions. They demand better answers. That's what real-time dashboards do. Not just inform. Activate. --- ## Delhi's Invisible Winter: What Really Happens to the Air Between October and February URL: https://aqi.news/blogs/delhi-winter-air-quality-explained Published: 2026-06-12 Author: AQI.news Editorial Team Every October, like a slow-motion alarm clock, Delhi's air begins its winter deterioration. The city hasn't changed overnight. The factories haven't multiplied. The cars haven't doubled. But the AQI starts climbing – 100, 150, 200 – and by November, on the worst days, the numbers scroll past 400 while the sky turns the colour of weak tea. What's happening? The honest answer is more complicated than the stubble burning debate suggests. Delhi's winter air crisis has been described, debated, and litigated so many times that a kind of collective numbness has set in. But understanding the actual mechanics – why winter specifically, why the dramatic spikes, why some years are worse than others – is essential for anyone who wants to make intelligent decisions about how they live in the city during these months. ### The Meteorological Trap The fundamental driver of Delhi's winter pollution is not a source. It's a container. The Indo-Gangetic Plain, on which Delhi sits, is one of the worst-ventilated geographical basins on Earth from an air quality perspective. Bounded to the north and east by the Himalayas and Siwaliks, and relatively flat in all other directions, the IGP has weak lateral airflow for large parts of the year. In winter, this structural disadvantage is compounded by temperature inversion. During the day, solar heating drives convection that helps disperse pollutants upward. At night, the ground cools rapidly, creating a layer of dense cold air near the surface. Above this sits warmer air – and this inversion layer acts as a lid, trapping everything produced at ground level. Dawn and early morning hours – when Delhi residents often venture out for walks and exercise – are frequently the most polluted parts of the day. The night's accumulated emissions have been trapped under an inversion that hasn't yet broken. ### Stubble Burning: Real, Significant, But Not the Whole Story October to November marks the paddy harvest period in Punjab and Haryana. Farmers burning crop residue – a practice that is economically rational given time pressure and the cost of alternatives – generates massive plumes of smoke that satellite imagery tracks moving directly into the NCR. This is a real and substantial contributor, particularly during peak burning weeks. Studies have attributed anywhere from 20% to 45% of Delhi's peak pollution load during these weeks to stubble burning, depending on the year and the weather. But here's what the stubble burning debate obscures: on the worst days, when AQI exceeds 400, stubble burning is typically amplifying a baseline that is already at 200+ from local sources. Remove the stubble burning entirely and Delhi still has a severe winter air quality problem. It just becomes a very severe one instead of a catastrophic one. The local sources – vehicular emissions (over 11 million registered vehicles), construction dust, industrial activity in the NCR periphery (Faridabad, Ghaziabad, Greater Noida), and biomass burning for heating – collectively form a year-round pollution burden that winter meteorology concentrates. ### Diwali: The Annual Spike Within a Crisis Diwali falls squarely within Delhi's already-compromised winter season. The fireworks emissions, while intense and dramatic, are relatively brief in duration. What makes Diwali's air quality impact severe is the timing: the fireworks load lands on top of an atmosphere already carrying maximum winter baseline pollution, often during an inversion event, with limited dispersion capacity. The result is typically Delhi's worst individual AQI readings of the year – sometimes exceeding 500 (the top of the standard scale) in the 48 hours around the festival. The spike typically lasts two to four days before reverting to the elevated winter baseline. ### Why Some Winters Are Worse Than Others If you've lived in Delhi for several years, you've noticed that not all winters are equally bad. Some November months are bearable; others are catastrophic. The primary variable is weather. Wind speed and direction matter enormously. Westerly winds of even modest speed can clear the city significantly. Calm, still conditions during an inversion event concentrate everything. Rainfall – even light rain – washes particulates from the atmosphere and provides dramatic, if temporary, improvement. This explains the apparent paradox of winters where stubble burning was extensive but Delhi's air was "not that bad" – because wind conditions carried the smoke elsewhere – and winters where stubble burning was lower than average but Delhi's readings were extreme, because meteorology provided no escape. The dashboard's 7-day and 14-day trend view makes this pattern visible. ### What Is Actually Being Done Delhi has implemented a range of policies – the Odd-Even vehicle rationing scheme, the Graded Response Action Plan (GRAP) with escalating restrictions tied to AQI thresholds, bans on coal and biomass burning, stricter industrial emission norms, and the expansion of the Delhi Metro. Progress on the vehicular side is real: the transition to BS-VI fuel in 2020 significantly reduced particulate and NOₓ emissions per vehicle. The Metro's ridership – pre- and post-pandemic – represents millions of vehicle trips avoided. What hasn't been solved: the fundamental meteorological trap, the agricultural burning coordination problem (which involves political will across multiple state governments), and the sheer pace of urban growth. ### Living Through It Intelligently The goal isn't to leave Delhi every winter. It's to make smarter daily decisions during the worst months. Check the live AQI in the morning before deciding whether today is a walk day or a window-closed day. Know when the inversions typically break (mid-morning, usually). Have an N95 available for commuting on genuinely bad days. The dashboard shows you what today is. That's a meaningful advantage over years past, when the only signal was whether you could see the buildings on the other side of the road. --- ## India's Air Quality Divide: Why Mumbai, Bangalore, and Kolkata Experience Pollution So Differently URL: https://aqi.news/blogs/india-air-quality-city-comparison Published: 2026-06-12 Author: AQI.news Editorial Team Mention "India and air pollution" and most people picture Delhi. That framing is both understandable and incomplete. India is a continent masquerading as a country, and its air quality story is fractured, regional, and shaped by factors as different as monsoon geography and industrial legacy. India is home to many of the world's most polluted cities. It also contains cities that regularly clock AQI readings that would be considered acceptable in Europe. Understanding why requires looking past the headlines and into the specific drivers – geography, industry, meteorology, urban density – that shape each city's air. ### Delhi NCR: The Most Studied, Still the Most Challenged Delhi is the anchor of India's air quality conversation for a reason. The combination of vehicular density (over 11 million registered vehicles in Delhi alone), proximity to stubble-burning agricultural regions in Punjab and Haryana, topographic trapping due to the Indo-Gangetic Plain's wind patterns, and construction activity creates a near-perfect storm for particulate accumulation. Winter months – October through January – are when Delhi's air turns from a chronic problem into an acute crisis. The meteorological condition called inversion, where a layer of warmer air traps cool polluted air near the ground, essentially puts a lid on the city and concentrates everything produced locally plus what drifts in from hundreds of kilometres away. The numbers in this period routinely exceed 300 AQI. On the worst days, the 500 ceiling of the standard AQI scale can feel like an understatement. ### Lucknow and Kanpur: The Unsung Gangetic Belt Cities If Delhi dominates the news, cities like Lucknow, Kanpur, and Varanasi often escape attention despite facing comparable or worse conditions for portions of the year. These cities sit in the same Indo-Gangetic Plain as Delhi, face the same inversion–driven trapping, but have less industrial monitoring infrastructure and weaker enforcement capacity. Kanpur, in particular, has historically ranked among the most polluted cities in the world in several international air quality reports – not because it is uniquely industrial, but because the combination of tanneries, vehicular emissions, and the Gangetic meteorology creates conditions that rarely get scrutinised the way Delhi's do. ### Mumbai: The Sea Breeze Advantage (and Its Limits) Mumbai's air quality is genuinely better than Delhi's for most of the year, and the primary reason is geography. The Arabian Sea creates persistent sea breezes that disperse pollutants before they accumulate to Delhi-like concentrations. But Mumbai is not clean. The city has serious issues with vehicular and industrial emissions, particularly in areas like Chembur and Malad that host industrial clusters. During Diwali and in the pre-monsoon months when sea breeze patterns weaken, Mumbai's AQI can jump to levels that would generate headlines if they occurred in Delhi. Mumbai's air quality also has a profound inequality dimension: residents of areas close to industrial zones or major arterial roads breathe air that is measurably worse than those in coastal or elevated neighbourhoods. The Marine Drive experience and the Dharavi experience are not the same atmosphere. ### Bangalore: The Altitude Myth Bangalore is often described as a city of pleasant weather and clean air. This reputation is partly deserved – at 900+ metres elevation, the city has better baseline dispersion conditions than low-lying plains cities – but it is being eroded quickly. Bangalore's AQI has been trending upward for a decade, driven primarily by a vehicle density explosion (the city adds hundreds of thousands of new vehicles annually), construction dust from its perpetual infrastructure boom, and a significant reduction in its tree canopy as tech campuses and apartment complexes replace the green corridors that once helped absorb pollutants. On a bad construction season day, parts of northern Bangalore can register AQI readings in the unhealthy range. The pleasant weather narrative is real, but increasingly precarious. ### Chennai: The Underreported Story Chennai has a relatively active pollution monitoring network for its size, yet air quality data from the city rarely enters national discourse. The city faces specific challenges from two-wheeler density (Tamil Nadu has among the highest two-wheeler penetrations in India), thermal power plants on its outskirts, and port-adjacent industrial activity. Chennai's AQI is generally moderate – better than the Gangetic belt, but worse than many assume given the city's coastal location. The monsoon, which brings heavy rainfall, provides a significant seasonal reprieve. October through January, however, sees rising particulate levels. ### Ahmedabad: Industry, Heat, and Wind Gujarat's largest city has a different pollution profile from either the Gangetic belt or coastal metros. Ahmedabad's air quality challenges are tied significantly to its industrial base – chemicals, textiles, pharmaceuticals – and to the dust events driven by its semi-arid climate. The city's wind patterns can both help and hurt: on high-wind days, pollutants disperse efficiently; on still, humid days, the city can see rapid AQI deterioration. Ahmedabad's summer months, when temperatures regularly exceed 40°C and construction activity peaks, are often its worst for air quality. ### The Data Point That Changes Everything Here is a number worth sitting with: India is home to more than 40 of the 50 most air-polluted cities in the world by PM2.5 annual average, according to global air quality databases. But the variation within India is enormous – from cities exceeding 100 µg/m³ annually to cities with readings closer to 25-30 µg/m³. That gap is not fate. It's the product of geography, policy, enforcement, and infrastructure. Which means it's closeable. The first step is knowing where you are, right now, on the dashboard. --- ## The AQI Number You've Been Misreading (And What It Actually Means for Your Body) URL: https://aqi.news/blogs/the-aqi-number-youve-been-misreading Published: 2026-06-01 Author: AQI.news Editorial Team You've seen the number — 147, 312, 78 — on a weather app or a headline about Delhi. But do you actually know what it means for what's happening inside your lungs right now? Most people don't, and it's not their fault. You've seen the number. Maybe on a weather app, maybe on the dashboard, maybe in a headline about Delhi. 147. 312. 78. But here's the honest question: do you know what any of those numbers actually mean for what's happening inside your lungs right now? Most people don't. And it's not their fault - the AQI system is simultaneously the world's most important environmental number and one of the most poorly communicated. ### What AQI Actually Is The Air Quality Index is not a single measurement. It's a translation. Multiple air pollutants - PM2.5, PM10, ozone, nitrogen dioxide, sulphur dioxide, and carbon monoxide - are each measured in their own units (micrograms per cubic metre, parts per billion, etc.). These different measurements are each converted into a standardised 0-500 scale using concentration breakpoints. The highest single-pollutant score becomes the composite AQI. What this means practically: an AQI of 150 could be driven by PM2.5, or by ozone, or by NO₂. The headline number looks the same, but the health implications and the sources are different. This is why good dashboards show you the individual pollutant breakdown, not just the aggregate number. ### The Six Categories - What Each One Actually Means - AQI 0-50 (Good): Air quality is satisfactory. Sensitive individuals (those with pre-existing respiratory or heart conditions) can exercise outdoors freely. For healthy adults, no restrictions needed. - AQI 51-100 (Moderate): Acceptable air quality for most people. Unusually sensitive individuals may experience minor effects from ozone. For the vast majority of healthy people, no noticeable impact. - AQI 101-150 (Unhealthy for Sensitive Groups): This is where the language of caution begins. People with asthma, older adults, and children should consider reducing prolonged outdoor exertion. Healthy adults are generally still unaffected. This range covers a large portion of India's "average" days in major cities. - AQI 151-200 (Unhealthy): Everyone begins to experience health effects. Active individuals, children, and those with respiratory conditions should limit outdoor activity. Delhi regularly exceeds this threshold during October-January. - AQI 201-300 (Very Unhealthy): Health alert: everyone may experience serious health effects. This is the range where N95 masks provide meaningful protection. Outdoor exercise should be avoided. - AQI 301-500 (Hazardous): Emergency conditions. The entire population is likely to experience serious health effects. On these days - which occur in Delhi and other northern Indian cities during peak pollution episodes - staying indoors with air filtration is not excessive caution. It's the appropriate response. ### The Misconception: "It's Not That Bad Today" Here's a critical insight the raw number hides: cumulative exposure matters more than any single day. An AQI of 160 for one afternoon is not the same as an AQI of 160 every day for three months. The body has some capacity to recover from acute exposures. It does not have the same capacity when the exposure is continuous and the recovery window never comes. This is why annual average PM2.5 exposure - not just peak episodes - is the metric epidemiologists use to model long-term health outcomes. If your city's annual average PM2.5 is above 15 µg/m³ (the revised WHO guideline), that represents a chronic health burden, regardless of how many individual days look "moderate." ### PM2.5 vs AQI: The Number That Matters More PM2.5 - fine particles smaller than 2.5 micrometres - is the single most health-relevant pollutant in the Indian context. These particles are small enough to penetrate deep into lung tissue and enter the bloodstream. The WHO annual guideline for PM2.5 is 5 µg/m³. The previous guideline was 10 µg/m³. Most Indian cities average 30-90 µg/m³ annually. Delhi averages significantly above that. When you check the dashboard and see the PM2.5 value alongside the AQI, the PM2.5 number gives you the most direct information about what your lungs are actually encountering. ### One More Myth: "Masks Don't Work" N95 respirators - when correctly worn and fitted - filter out 95% of particles 0.3 microns and above. Since PM2.5 sits between 0.1 and 2.5 microns, a properly worn N95 provides genuine protection on high-AQI days. Surgical masks are not equivalent. Cloth masks are not equivalent. The protection is largely in fit and filtration grade, which is why the mask you wear on a 300 AQI day matters. --- # Usage AQI.news public content may be indexed, summarized, and cited with attribution to AQI.news. Live AQI values change continuously — when referencing a reading, link users to the relevant page on https://aqi.news for the current number rather than quoting a value as a fixed fact. Reference-library pages are stable and safe to quote.