At a glance
What matters most
- 01
The European index uses six categories: Good, Fair, Moderate, Poor, Very Poor and Extremely Poor.
- 02
It uses hourly concentrations for PM2.5, PM10, ozone, nitrogen dioxide and sulfur dioxide.
- 03
The poorest available pollutant category determines the overall index level.
- 04
The EEA states that the index cannot be used to check compliance with legal air-quality standards.
The six European index categories
| Category | What it communicates |
|---|---|
| Good | The lowest short-term pollution band. |
| Fair | Generally suitable for usual outdoor activity. |
| Moderate | Sensitive people may consider reducing intense activity if they experience symptoms. |
| Poor | Stronger precautions may be appropriate, especially for sensitive groups. |
| Very Poor | Reduced physical activity is advised for sensitive groups. |
| Extremely Poor | The highest short-term pollution band and strongest health concern. |
Pollutants and the worst-level method
The index evaluates hourly concentrations of PM2.5, PM10, ozone, nitrogen dioxide and sulfur dioxide. Each available pollutant is assigned a category from its concentration band, and the poorest level determines the overall index for that station or model grid.
The station layer combines up-to-date measurements reported by participating countries with modelled gap filling where needed. A separate modelled layer provides broader geographic coverage, including locations without a nearby monitoring station.
European hourly concentration bands
| Pollutant | Good | Fair | Moderate | Poor | Very Poor | Extremely Poor |
|---|---|---|---|---|---|---|
| PM2.5 | 0–5 | 6–15 | 16–50 | 51–90 | 91–140 | >140 |
| PM10 | 0–15 | 16–45 | 46–120 | 121–195 | 196–270 | >270 |
| Ozone | 0–60 | 61–100 | 101–120 | 121–160 | 161–180 | >180 |
| Nitrogen dioxide | 0–10 | 11–25 | 26–60 | 61–100 | 101–150 | >150 |
| Sulfur dioxide | 0–20 | 21–40 | 41–125 | 126–190 | 191–275 | >275 |
Stations, modelled coverage and forecasts
The EEA map distinguishes recent station observations, model-assisted gap filling and modelled grid estimates. Forecast layers use atmospheric modelling and should not be interpreted as verified monitor observations.
Because the index is hourly, it can change quickly and can differ between nearby stations, traffic locations, urban background sites and model cells. Compare the timestamp, layer and pollutant details before comparing places.
Why the index is not a compliance test
The European Air Quality Index describes short-term conditions. EU legal standards use specific hourly, daily or annual averaging periods, permitted exceedances, approved monitoring methods and data-quality requirements. The EEA therefore explicitly states that its index cannot be used to check legal compliance.
Frequently asked questions
Does the European Air Quality Index use a 0–500 number?
No. The EEA presents six named categories based on pollutant concentration bands rather than the US-style 0–500 headline scale.
Is European AQI the same as US AQI?
No. They use different scales, concentration bands, averaging approaches and category names. Compare the underlying pollutant concentration and time period instead of assuming categories are equivalent.
Which pollutant determines the European index?
The poorest category among the available PM2.5, PM10, ozone, nitrogen dioxide and sulfur dioxide readings determines the overall level.
Can the European index prove compliance with EU law?
No. The EEA states that the index is for current air-quality communication and cannot be used to check compliance with legal standards.
Primary sources
This reference was prepared from the following primary public-health and regulatory sources: