The Ontario Ministry of the Environment monitors air quality and issues forecasts. There are three categories in their air quality forecasts: good (0-31), moderate (32-49), and poor (50+). When there is a 50% chance that smog levels will reach the poor category within the next 72 hours, the Ministry of the Environment will issue a Smog Watch. If the air quality level is expected to reach 50 on the Air Quality Index (AQI) or more within the next 24 hours or if poor air quality is unexpectedly in a particular region and will last for several hours, the Ministry of the Environment will issue a Smog Advisory. Once the air quality has improved, a Smog Termination notice is issued. Anyone can sign up to have air quality forecasts sent directly to their email address. To register, please visit www.airqualityontario.com

The newer Air Quality Health Index (AQHI) was piloted in selected cities across Canada since 2005. On June 6, 2008, the AQHI was expanded across the Greater Toronto Area. This national health based index takes into consideration the cumulative effects of a mixture of air pollutants (ozone, fine particulate matter and nitrogen dioxide), rather than just the dominant pollutant in the final air quality index. The new AQHI is more protective of health than the provincial AQI as research has shown that there can be increased health effects when more than one pollutant is elevated.

The AQHI is designed to help you make decisions to protect your health by limiting short-term exposure to air pollution and adjusting your activity levels during increased levels of air pollution. It also helps you understand your response to different pollution levels to help you plan and enjoy outdoor physical activities at times when health risks are low. This index, which is based on a ten point scale, pays particular attention to people who are sensitive to air pollution and provides them with advice on how to protect their health during air quality levels associated with low (0-3), moderate (4-6), high (7-10) and very high (over 10) health risks.

For more information, please visit the Federal government or Region of Halton websites.