Particulate Matter (PM) levels and AQI

An air quality index (AQI) is used by government agencies to communicate to the public how polluted the air currently is or how polluted it is forecast to become. Public health risks increase as the AQI rises.

Different countries have their own air quality indices, corresponding to different national air quality standards. Some of these are the Air Quality Health Index (Canada), the Air Pollution Index (Malaysia), and the Pollutant Standards Index (Singapore).


The Common Air Quality Index (CAQI) is an air quality index used in Europe since 2006. In November 2017, the European Environment Agency announced the European Air Quality Index (EAQI) and started encouraging its use on websites and for other ways of informing the public about air quality.

Qualitative name Index PM2.5 (1-hr) μg/m³ PM10 (1-hr) μg/m³
Very high >100 >110 >240
High 75-100 55-110 90-180
Medium 50-75 30-55 50-90
Low 25-50 15-30 25-50
Very low 0-25 0-15 0-25

United States

The United States Environmental Protection Agency (EPA) has developed an Air Quality Index that is used to report air quality. This AQI is divided into six categories indicating increasing levels of health concern. An AQI value over 300 represents hazardous air quality and below 50 the air quality is good.

Qualitative name Index PM2.5 (24-hr) μg/m³ PM10 (24-hr) μg/m³
Hazardous 301-500 250-500 425-604
Very Unhealthy 201-300 150-250 355-424
Unhealthy 151-200 55-150 255-354
Unhealthy for Sensitive Groups 151-200 55-150 155-254
Moderate 51-100 12-35 55-154
Good 0-50 0-12 0-54 - Particulate Matter (PM) Pollution
What is Air Quality Score (AQS)?