Key Messages
Air Quality Health Index
Air Quality and Asthma
Technical Notes
- Air quality in Barrie and Dorset is very good, with low air quality health risk 99% of the time.
- There was one day in 2021 where high air quality health risk was reported in Barrie. This is the first time since 2014 where high air quality risk was reported.
- There is a strong association between air quality health measurements and asthma-related emergency room visits.
Air Quality Health Index
- In 2021, 99% of monitored hours in Barrie and Dorset had low air quality health risk, as measured by the Air Quality Health Index (AQHI).
- There was one day in 2021 where four hours were reported with high air quality health risk in Barrie, in July. Prior to this, there had been no ‘high risk’ AQHI hours in Barrie since 2014, and none with a ‘very high risk’ reading in Barrie since 2003.
- Between 2003 and 2010, there was a significant and steady increase in the proportion of hours that were low risk in Barrie (1.7% per year). Since 2010, and air quality in Barrie has remained consistently high, with no significant trend.
- Air quality in Dorset Station in Muskoka has remained consistently good. Generally fewer than 1% of monitored hours at Dorset registered as moderate risk.
- The last high risk hours reported in Dorset were in 2007, and no very high risk hours were reported from 2003 to 2021. This aligns with the relatively lower exposure to traffic related air pollution and other sources of air pollution in the more rural setting.
Air Quality and Asthma
- There is a strong association between air quality health index risk and asthma-related emergency room visits.
- From 2003 to 2021, there was a very strong correlation (R=0.90) between the age-standardized rate of asthma-related emergency room visits in Simcoe County and the percent of hours in a year with moderate or higher AQHI ratings in Barrie.
- Similarly, there was strong correlation (R=0.78) between the age-standardized rate of asthma-related emergency room visits in Muskoka District and the percent of hours in a year with moderate or higher AQHI in Dorset.
- Correlation does not imply causation; however, this evidence supports other research showing the health benefits of improved air quality.
Technical Notes
The ambient air monitoring station in Barrie is the only one in Simcoe Muskoka that collects hourly data on all three pollutants needed to calculate the AQHI.
Health Canada and Environment Canada developed the Air Quality Health Index (AQHI) as a public information tool to help Canadians protect their health from the negative effects of air pollution.
The AQHI is a scale that goes from 1 to 10+ and represents the increased risk of death based on the level of three pollutants in the ambient air: fine particulate matter (PM2.5), ozone (O3) and nitrogen dioxide (NO2). This scale is then sub-divided into four health risk categories:
Further Reading
For more information about air quality in Simcoe Muskoka and the Air Quality Health Index, see:
Page updated July 10, 2023
Page last modified February 8, 2023