2011 Air Quality in Ontario Report
Ministry of the Environment
Ontario's air quality is improving
The 2011 air quality report marks 41 years of long-term reporting on the state of air quality in Ontario. This report summarizes the current state and province-wide trends for key airborne pollutants impacting Ontario's air quality.
Overall, air quality has improved significantly over the past 10 years, especially for nitrogen dioxide (NO2), carbon monoxide (CO) and sulphur dioxide (SO2) -- pollutants emitted by vehicles and industry -- as well as fine particulate matter (PM2.5), which originates from many different industrial and transportation sources as well as natural sources.
Ozone is a secondary pollutant formed when nitrogen oxides (NOx) and volatile organic compounds (VOCs) chemically react in the presence of sunlight. Ozone annual means have increased by seven per cent from 2002 to 2011.
Transboundary emissions, mainly from the U.S., account for approximately half of Ontario's smog. Emission reductions in Ontario and the U.S. have contributed to decreases in PM2.5 and summer ozone levels. Winter and annual ozone levels are increasing due to a global rise in ozone levels.
Ontario emissions are decreasing
Emissions of NOx, CO and SO2 continue to decrease due in part to Ontario's air quality initiatives such as the phase-out of coal-fired generating stations, emissions trading regulations, emissions controls at Ontario smelters, and Drive Clean automobile emission limits.
The Ontario Ambient Air Quality Criteria
During 2011, the provincial Ambient Air Quality Criteria for NO2, CO and SO2 were not exceeded in any regions of Ontario where ambient air monitoring exists.
The Canada-wide Standard
For a fourth year in a row, the Canada-wide Standard for PM2.5 was not exceeded in Ontario. The PM2.5 Canada-wide Standard three-year metrics are trending downwards from 2005 to 2011.
Six of the 21 designated sites met the Canada-wide Standard for ozone in 2011. For the first time, Barrie, London, Mississauga, and Sudbury met the Canada-wide Standard for ozone. The ozone Canada-wide Standard three-year metrics are trending downwards from 2005 to 2011.