Did You Know? – The average car releases 225g of GHGs per km. If every driver in Ontario drove 10km less per year, we would cut annual air pollutants by 13,500t

cloud air

The issue of air pollution, like air itself, is hard to grasp. Often simply mistaken as a matter of clean versus dirty, air pollution actually pertains to a wide variety of environmental issues, some of which are closely related and some of which are almost entirely independent. Various air pollutants can have local, regional, and global impacts, and can stay in the atmosphere after being emitted anywhere from a few hours to thousands of years.

The most salient air pollution issue at present is increasing greenhouse gas (GHG) concentrations in the atmosphere, which are a major contributor to anthropogenic climate change. The latest report by the Intergovernmental Panel on Climate Change (IPCC) notes that the current atmospheric CO2–equivalent concentration is about 380ppm – up from 320ppm in 1965 – and that we will need to stabilize this concentration under 500ppm by 2100 in order to avoid risking serious global impacts, such as widespread water shortages, famine, and disease. Doing this will require worldwide GHG emissions to reduce by at least 50% by the year 2050. GHG emissions primarily come from fossil fuel combustion and the release of other substances – such as methane, nitrous oxide, and halocarbons – from various sources.

Interestingly, carbon dioxide is often not actually considered a pollutant; increased carbon dioxide concentrations actually help plants grow, and will not reach levels that have any direct negative impacts on living beings. The only adverse effect of rising CO2 concentrations – albeit and enormous one – is the anthropogenic climate change it is causing. Natural greenhouse gases in the atmosphere (which both CO2 and methane are) in their normal concentrations actually help keep the global climate livable – the earth would be about 33oC colder otherwise!

The distinction above is an important one, because there are other air pollutants that are actually harmful in any concentrations. Sulfur oxides and nitrogen oxides (SOx & NOx) released from poorly filtered fossil fuel combustion emissions cause acid rain, and they contribute to two different varieties of smog. The mixture of sulfur dioxide with smoke forms classic smog, and the reaction of nitrogen oxides with volatile organic compounds (VOCs) and sunlight forms a mixture of airborne particulate matter and tropospheric ozone known as photochemical smog, which is common in large urban areas. Both forms of smog have serious adverse health effects, primarily by causing a variety of respiratory diseases. Finally, the release of chlorofluorocarbons (CFCs) cause the depletion of the ozone layer, which results in hazardous amounts of ultraviolet radiation being transmitted through the atmosphere.

North America in general has already taken great steps to address most air pollution issues. The Montreal Protocol, an international treaty that entered into force in 1989, phased out the use of ozone depleting substances, and government agencies regulate the emissions of acid rain, smog forming, and other toxic pollutants. The main class of air pollutants that has not yet been adequately regulated is GHGs. The Kyoto Protocol entered into force in 2005, but at present few countries look to be hitting their targets, including Canada


Clean Air Online (Enviroment Canada)


Environment Canada – Air

Environment Canada – Climate Change

Ontario Ministry of Environment – Air

Toronto Atmospheric Fund

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