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
Does PM10 include PM2.5?
Yes. PM2.5 is the fine-particle portion within the broader PM10 size category.
Can dust cause high PM10?
Yes. Construction, roads, soil, mining, demolition and windblown dust can all contribute to PM10.
Is PM2.5 always more important than PM10?
PM2.5 generally penetrates deeper and is especially important for health, but high PM10 can still create meaningful respiratory and environmental concerns.
Sources
This reference was prepared from the following primary public-health and regulatory sources:
- WHO Global Air Quality GuidelinesWorld Health Organization
- Particulate Matter (PM) BasicsUnited States Environmental Protection Agency
- Health and Environmental Effects of Particulate MatterUnited States Environmental Protection Agency