Outdoor Air Quality

The Air Quality Health Index is a national health-based index that helps individuals protect their health, and the health of people in their care. 

It measures air quality in relation to people's health on a scale from one to 10+.  The higher the number, the greater the health risk and the greater need for people to take precautions when spending time outdoors.

The new Index was developed by environmental and health professionals to communicate the health risk posed by local air pollution conditions.

The AQHI was piloted in the City of Toronto in 2007 and expanded to the GTA on June 4, 2008.

The AQHI is based on the relative risks of a combination of common air pollutants that are known to harm human health.  These pollutants include ozone (O3), fine particulate matter (PM2.5 and PM10) and nitrogen dioxide (N02).

No.  The AQHI does not replace the existing Air Quality Index (AQI) that triggers smog advisories. Instead, the new system being tested measures individual health risk and enables people to better protect themselves and people in their care from the harmful effects of air pollution.