Canadian Lung Association Blog

What makes up air pollution?

As the summer months roll on, we may hear regular air quality or smog alerts in the news. But what exactly happens in order for air pollution levels to be high?

Air pollutants come from many sources, such as traffic and vehicle emissions, industrial activities (factories, steel mills, and power plants), residential sources (wood burning, driving the car often), and transboundary sources (from the United States). In the warm summer months, many of these pollutants can linger around in the air, especially if there is little wind movement.

There are a number of chemicals that make up air pollution, such as ground-level ozone, fine particulate matter, nitrogen dioxide, sulphur dioxide, and carbon monoxide. Visit here for more details on these chemicals.

The Air Quality Health Index (AQHI) is available in many communities across Canada and it reports on the health risk associated with air pollution at a given time. It measures air pollutants that are known to harm human health (ozone, particulate matter, and nitrogen dioxide), and provides the combined overall health risk from the three pollutants. The AQHI is a scale from 1 to 10+ that provides health messages directed towards the general population and people “at risk” – young children, the elderly, people who are active outdoors, and people with heart or lung conditions. Visit to find the AQHI reading in your area – the higher the number, the higher the risk.

Stay updated on the air quality levels in your local area, especially if you have lung disease. It is important to reduce exposure to air pollutants as much as possible in order to reduce your risk.

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Connie Choy

Connie Choy is the Air Quality Coordinator at the Ontario Lung Association.

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Posted in Air Quality, Lung Health
2 comments on “What makes up air pollution?
  1. Kirby says:

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    I am new to this research. Thanks for helping me explore this topic – Kirby

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