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Air Pollution In Canada - Is It Possible?

Although air pollution in Canada is not as severe as some other areas in the world, it still can be a problem. For example, the south-eastern parts of Canada along the Windsor-Québec City corridor of Ontario and Québec, as well as southern Nova Scotia are renowned for smog and acid rain events in the summer months (June, July and August).

Gas plant

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While, these events of air pollution in Canada are a worry, you need to understand that the concentration of air pollutants fluctuates markedly throughout the course of one day. It's true that heat wave conditions in summer are more likely to contribute to the influx of high levels of smog.

The eastern parts of Canada has the worst air pollution

In eastern Canada, the most severe air pollution events occur in summer. It's caused mainly by industrial sources that have been blown in from the mid-western United States. In fact, during the summer months in Windsor (Ontario), around 70% of this smog is directly related to industrial sources coming in from over the United States border.

Even worse, around 90% of the acid rain that reaches southern Nova Scotia also originates from industrial sources within the United States. Most of the acidifying agents in the air bypass the major cities in southern Ontario and Québec.

Acidic mist over Kejimkujik National ParkYou may be surprised to learn that the southern parts of Nova Scotia has the worst acid rain events in all of Canada. This occurs mainly in the summer. The main area where this acid rain falls is within Kejimkujik National Park.

In eastern Canada, most of these smog events occur from mid-spring through till mid-autumn. As a general rule, the hotter the weather is, the more pollution there will be. Why? Well, most of the air pollution in Canada during heat wave conditions is caused by the frequent influx of hot humid air coming in from the United States (U.S). Unfortunately, this air is normally quite polluted since it passes over the industrial regions of the mid-western U.S before continuing on its journey towards the south eastern corner of Canada.

So if you happen to travel to regions where air pollution in Canada is high during a heat wave, then please be careful. You don't want to end up with respiratory problems.

An interesting case of air pollution in Canada occurred in the city of Sudbury, Ontario from the late nineteenth century to the 1950's. The region around Sudbury recorded toxic levels of atmospheric SO2 due to intensive iron, copper and nickel mining practices. As a consequence, many forests in the region suffered due to acid rain. Since the 1960's, there has been a 90% decrease in the amount of SO2 emissions and approximately eight million trees have been planted to replace the ones lost.

Beware of air pollution in the large Canadian prairie cities

Most of the cities located in the prairies aren't subject to severe air pollution events like the south eastern parts of Canada. However, this region does have locally produced air pollution which still can lead to health problems.

The main cities I'm talking about are Edmonton, Calgary, Regina, Saskatoon, and Winnipeg.

The majority of the air pollution events within these cities comes from sources such as:

  • home heating (wood burning)

  • vehicle emissions

  • soil and road dust

A small amount of air pollutants come from industrial sources.

As you would expect, vehicle emissions combined with soil and road dust rapidly increase when the majority of people start travelling to work (i.e between 8am-10am). Typically, you normally see this pollutant as a grey haze in the distance.

If you're located in a city or town that's in a valley (for example, Calgary) then you're more likely to have air pollution problems at night. The main air pollutant at night is from smoke due the widespread use of wood fires for household heating. Smoke levels can increase dramatically when there's hardly any wind, the sky is clear and you're located in a valley.

That's why you should be careful walking around at night in cities/towns that are surrounded by mountains. If you have any pre-existing respiratory problems, then of course you'll need to be extra careful.

Air pollution in Canada caused by agricultural practices

There's over 7000 pesticides in use in Canada. Out of these around 500 active ingredients are registered to be used mainly for agriculture.

The main region in Canada used for agriculture is located in the southern parts of Alberta, Saskatchewan and Manitoba (known locally as the Prairies). This region has the highest pesticide usage in Canada.

Consequently you should make sure that your travel plans don't overlap with the timing of the application of these insecticides. You'll need to ask around locally to find this out.

The last thing you want is to be accidentally inhale or expose your skin and eyes to these chemicals since it can lead to respiratory illness, eye irritation as well as other health problems.

Once you've established the location of where the pesticide spraying occurs, make sure that you don't stay in accommodation that's downwind of the source. In most instances, the farmer knows exactly under what weather conditions to apply the pesticide so that very little of it is actually blown away.

If the wind is strong however, the pesticide spray can travel hundred's of kilometres downwind. But by this time, the pesticide starts to disperse.

What other parts of Canada have air pollution problems?

Another region that has received considerable attention is the lower Fraser valley (located on the western coast of British Columbia). This region is surrounded by forested mountains to the north and the south. The southern section intersects the Canada/US border. The Strait of Georgia is located to the west.

As you probably know Vancouver is the main city in this region and so the air pollutants can affect a lot of people. The main problems in the summer result from car fumes (NOx) and surface ozone (O3). Thick smog over Vancouver during the summerThis O3 tends to increase during the daylight hours in summer. Whereas at night O3 decreases and other types of air pollutants begin to pose a health risk.

Please note:

Ozone air pollution in Canada is a problem not only in Vancouver, but also in almost every large city in Canada.

In the winter, you may also be contributing to the air pollution problem since you need to stay warm. Again smoke levels from residential wood burning for heating increases dramatically. The town of Golden located due west of Calgary suffers from this type of air pollution in the winter.

You'll be happy to know that the Canadian government has been working hard to reduce these smog levels over the last decade. However, there still needs to more done to clean the air in this region.

What locations in Canada don't normally get air pollution?

At this stage, the northern parts of Canada as well as areas around Labrador and Newfoundland have minimal air pollution problems. This shouldn't come as any surprise to you since these locations are far away from both industrial and agricultural sources.

So in conclusion, air pollution in Canada is quite bad in the south-eastern parts as well as in the valleys of British Columbia. I'm not sure if the air pollution problems in Canada can be rectified since the population is expected to continue increasing. So the initiatives put in place now by the government may be too little too late.


  1. DesJardins MJ, Telmer K and Beauchamp S. Apportioning atmospheric pollution to Canadian and American sources in Kejimkujik National Park, Nova Scotia, using Pb isotopes in precipitation. Atmospheric Environment. 2004;38(39):6875-6881.

  2. Cheng L, Sandhu HS, Angle RP and Myrick RH. Characteristics of inhalable particulate matter in Alberta cities. Atmospheric Environment. 1998;22(22):3835-3844.

  3. Ainslie B and Steyn DG. Spatiotemporal trends in episodic ozone pollution in the Lower Fraser Valley, British Columbia, in relation to mesoscale atmospheric circulation patterns and emissions . Journal of Applied Meteorology and Climatology. 2007;46(10):1631-1644.

  4. Yao Y, Harner T, Blanchard P, et al. Pesticides in the atmosphere across Canadian agricultural regions. Environmental Science and Technology. 2008;42(16):5931-5937.

    Additional information regarding the air pollution in Canada will be made available in due course.

    Return from air pollution in Canada to the weather in Canada page

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