Progressing forward: moving from the air quality index to the air quality health index

The Environmental Monitoring and Reporting Branch at the Ministry of the Environment and Climate Change (MOECC) continuously collects near real-time data for up to six criteria pollutants (ozone, PM2.5, NO2, SO2, CO and TRS compounds) from 39 ambient air monitoring sites as displayed in Map A1 of the Appendix.

On June 24, 2015, in partnership with ECCC, the ministry introduced the new AQHI to replace the previous AQI. Ontario’s AAQC, for the common criteria pollutants, was the foundation of the AQI. The AQI reported air quality based on the pollutant recording the highest sub-index for a single pollutant at each site. The purpose of the AQI was to inform the public about air quality and the potential of smog to influence public/industry behaviour and protect public health.

The AQHI derives a value based on the cumulative health effects of three pollutants – ozone, PM2.5 and NO2. The AQHI was developed and implemented by Health Canada with the assistance of ECCC and all provinces. Ontario’s AQHI combines the best features of the federal AQHI and the previous AQI by incorporating Ontario’s AAQC for the common criteria pollutants with the health risks associated with ozone, PM2.5 and NO2. It provides real-time air quality measurements using a scale of one through 10 or greater, with lower numbers representing better air quality, as depicted in Figure 18. Index values between one and three are considered low risk, four to six are moderate risk, seven to 10 are high risk and greater than 10 are very high risk. Table 2 outlines the health messages associated with the AQHI. The ministry website, www.airqualityontario.com, provides index values and corresponding categories and health messages.

Figure 18: AQHI Scale

Figure 18 is a graphic of the Air Quality Health Index scale which ranges from one to 10 plus.

Source: Environment & Climate Change Canada.

Table 2: Air Quality Health index Categories and Health Messages
Health Risk Air Quality Health Index Health Messages - At Risk Population* Health Messages - General Population

Low

 1-3 Enjoy your usual outdoor activities Ideal air quality for outdoor activities.

Moderate

 4-6 Consider reducing or rescheduling strenuous activities outdoors if you are experiencing symptoms. No need to modify your usual activities unless you experience symptoms such as coughing and throat irritation.

High

 7-10 Reduce or reschedule strenuous activities outdoors. Children and the elderly should also take it easy. Consider reducing or rescheduling strenuous activities outdoors if you experience symptoms such as coughing and throat irritation.

Very High

 Above 10 Avoid strenuous activities outdoors. Children and the elderly should also avoid outdoor physical exertion. Reduce or reschedule strenuous activities outdoors, especially if you experience symptoms such as coughing and throat irritation.

*People with heart or breathing problems are at greater risk. Follow your doctor’s usual advice about exercising and managing your condition.
Source: Environment & Climate Change Canada

Based on the AQHI categories, in 2015, Ontario reported low risk air quality 89.79 per cent of the time, moderate risk 10.17 per cent of the time, and high risk only 0.04 per cent of the time; there were no very high risk hours reported. Table A22 of the Appendix provides the percentage distribution of hourly AQHI readings for each of the 39 monitoring sites by AQHI value and the number of high risk AQHI days.

Air quality alerts

In 2015, with the introduction of the AQHI, Ontario began issuing air quality alerts that include a two-level alert system, issued in partnership with ECCC. The first level is a Special Air Quality Statement (SAQS), which informs the public of the potential for degrading air quality and is issued if an AQHI of 7 or greater is expected to last for 1 or 2 hours (i.e., “pop-up”). A SAQS is also issued for areas where forest fire smoke is expected to cause deteriorating air quality. The second level is a Smog and Air Health Advisory (SAHA), issued when “high risk” AQHI levels (AQHI of 7 or greater) are expected to be persistent and continue for 3 hours or more. The SAQS does not constitute a SAHA, but serves as a notification for Ontarians, especially those at risk, to pay attention to air quality and adjust their activities if adverse health effects are observed.

Air quality alerts are issued via the ministry’s web site, ECCC’s website, and through email air quality alert notifications. To subscribe for air quality alert notifications, please visit the ministry web site.

Ontario did not issue a SAHA in 2015, however, there were seven SAQS issued for regions across the province. Three SAQS were issued for parts of northwestern Ontario due to forest fire smoke originating from Manitoba and/or Saskatchewan. The remaining SAQS were all issued as a result of elevated ozone concentrations in southern Ontario. Table A23 of the Appendix summarizes the number of SAQS and SAHA issued for Ontario in 2015.

Access to air quality information

Near real-time and historic pollutant concentration data and AQHI values are available to the public (24 hours per day, 7 days a week) from across the province on the ministry’s web site www.airqualityontario.com. The public can also access index values via the Interactive Voice Response (IVR) system.  (To access a recording in English or French, call 1.800.387.7768, or in Toronto, call 416.246.0411.)  The ministry’s web site also provides air quality forecasts throughout the day, based on regional meteorological conditions and current pollution levels in Ontario and bordering American states.