Map of Simcoe Muskoka


Air Quality Health Index

Key Messages
Air Quality Health Index
Air Quality and Asthma
Technical Notes

Key Messages

  • Air quality in Barrie is very good, with low air quality health risk 98% of the time.
  • There have been no measurements of high air quality health risk in Barrie since 2014.
  • There is a strong association between air quality health measurements and asthma-related emergency room visits.

Air Quality Health Index

  • In 2020, 99% of monitored hours in Barrie had low air quality health risk, as measured by the Air Quality Health Index (AQHI)
  • Between 2003 and 2010, there was a significant and steady increase in the proportion of hours that were low risk (1.7% per year), and air quality has remained consistently high since.


In Barrie in 2020, the vast majority (99%) of monitored hours had ‘low risk’ AQHI readings and all of the remaining monitored hours (1%) were considered ‘moderate risk’. There have been no ‘high risk’ AQHI hours in Barrie since 2014, and none with a ‘very high risk’ reading in Barrie since 2003.

There was a significant increasing trend in the per cent of ‘low risk’ hours from 2003 to 2010, with an average annual increase of 1.7% (0.9%, 2.6%) per year. However, from 2010 to 2020 the trend for the per cent of hours in the ‘low risk’ AQHI range has evened out, with no significant increases or decreases.

Air Quality and Asthma

  • There is a strong association between air quality health index risk and asthma-related emergency room visits.
  • From 2003 to 2020, there was a very strong correlation (R=0.91) between the age-standardized rate of asthma-related emergency room visits in Simcoe Muskoka and the percent of hours in a year with moderate or higher AQHI ratings (in Barrie).
  • 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 last modified April 12, 2022