Climate Change, Air Quality, and Public Health

air quality

Canada has some of the cleanest air on the planet.[1]

But the truth is, many Canadians—especially in urban centres—are finding it more difficult to breathe easy. For example, instead of fresh spring air, the first day of Toronto’s 2019 spring break arrived with an air quality warning thanks to high levels of air pollution.[2]

We are profoundly affected by the air we breathe. Across the globe, clinical and public health research has shown that air pollution causes an enormous disease burden and increased hospitalizations for a variety of conditions.

Some of these impacts involve sudden-onset breathing problems, but increasingly, we’re seeing that chronic diseases can also develop from long-term exposure to air pollution. These diseases include chronic obstructive pulmonary disease (COPD), heart disease, cancer, and more. [3][6] In the early stages of life, bad air quality can prevent proper lung development in children. And even before a child is born they can experience the effects of poor air quality, as women’s exposure to pollutants while pregnant increases the risk of having a low-birth-weight child.[3]

We know intuitively that clean air is good for us, and polluted air is bad for us. What’s much less obvious to most of us is the link between climate change and the air we breathe. There’s a growing body of research that connects our changing climate to worsening air quality. Understanding that connection is important to our health as humans.[3][4][5]

Climate Change and Air Quality

Climate change and its root causes are contributing to air pollution in two ways. First, when climate change-causing greenhouse gases are released into the atmosphere, other harmful pollutants are released at the same time. Second, the impacts of climate change, such as increased heat and more wildfires, also increase air pollution.

Climate change is associated with four air pollutants in particular that can affect our health [6][7]:

  • Nitrogen oxides are some of the many harmful by-products of fossil fuel combustion. They are powerful lung irritants that can also be transformed into other kinds of harmful pollution by chemical reactions in the air.
  • Ozone is a lung-damaging chemical when it’s found at ground level where we can breathe it in. It causes inflammation, resulting in what is often explained as a “sunburn on your lungs”. [8] It’s also a primary contributor to the heavy smog we associate with cities like L.A or Beijing. Ozone is produced by a chemical reaction that happens more easily at warmer temperatures. That means the more the climate warms, the more ozone we can expect to breathe.
  • Particulate matter is made up of small particles that float around in the air. They can come from many sources, such as car exhaust or industrial processes. The tiniest kinds of particles pose the biggest risk to our health because they are able to move furthest into our lung tissues. Climate change is projected to increase the amount of fine particulate pollution we are exposed to thanks to increased risk of wildfires and other mechanisms that release particles into the air, where we are forced to breathe them.
  • Allergens like pollen, mold, and mildew are also beneficiaries of climate change thanks to higher temperatures and longer growing seasons. Those of us with allergies and asthma know these seasonal irritants all too well, and the sneezing, wheezing, and itchy eyes that accompany them.[9] Longer allergy seasons allow for more of this matter to develop and spread in our environment.

Read More: Ozone

Ozone is most often talked about as the ozone layer in the outer atmosphere, where a layer of this gas protects us from the sun’s harmful UV rays. When it is in this location, far far away, ozone is good for our health. However, ozone can also be found at ground level, and it is harmful when it makes its way into our lungs. [10]

The formation of ozone is not straightforward: it depends on the presence of two types of pollutants in the air, plus sunlight (or more specifically, the energy derived from sunlight). These pollutants are:

Nitrogen Oxides, often called NOx (pronounced “knocks”), are the compounds nitric oxide and nitrogen dioxide. These come from natural sources like soil, forest fires and other vegetation fires and human activities like fossil fuel combustion in cars and industrial processes.[10]

Volatile Organic Carbons, more simply referred to as VOCs. These are gases that come from a variety of natural sources like plants and soil, but also unnatural sources like gasoline (before or after combustion), paint thinner, and paint to name a few of the more common ones. There are approximately 120 different chemicals that are classified as VOCs, and each of them can serve as a chemical precursor to ozone formation. [10]

The more NOx and VOCs that are in the air, the higher the level of ozone will be. [10]

Ozone is an unstable molecule that reacts quickly with most things it encounters. This is useful in industrial processes, but harmful to us when we inhale it: it reacts with our bodies to produce unpleasant sensations and a variety of health impacts. The majority of the acute symptoms associated with ozone exposure directly impact our throat and lungs; however, long-term exposure to ozone can also affect the nervous and cardiovascular systems, too. [8]

Read more : Wildfire smoke and dust

In recent summers the devastating wildfires of Fort McMurray and British Columbia took over the mainstream media, and made the consequences of climate change a bit more real for Canadians. Smoky skies became the backdrop for summer in many municipalities. Individuals were advised to stay indoors because the air quality impacts of smoke from the fires was considered high risk. (Read more about the impacts of wildfire smoke on human health in “Wildfire Smoke and Climate Change”.)

For many Canadians dust may seem a bit more innocuous than ominous clouds of wildfire smoke rolling in. But anyone who has choked on the dust kicked up on a dry gravel road or seen images of the 1930s Dust Bowl, can begin to imagine the dusty consequences of the increasingly dry summer conditions associated with climate change in many parts of southern Canada. Lower levels of soil moisture mean that more and more dust particles can become airborne and make their way into our respiratory systems. [12] Check out our map of summer precipitation to see projected change across the country.

Pollution + Heat = Risk

Heat and pollution work together to expose us to more risks and at the same time make us less able to deal with them. For instance, at elevated temperatures we tend to breathe in more air, which means we also breathe in more pollutants.

And when it’s hot, our bodies try to retain as much water as possible, especially if we don't drink additional water to help deal with the heat. This means our kidneys can become less able to remove toxins from our bodies by excreting them in urine. So drinking lots of water during high temperatures is helpful not only for comfort but also for managing our resilience to poor air quality as well. [11]

Chances are, at some point we have all experienced the effects of poor air quality. Allergens and irritants often cause coughing, sneezing, wheezing, irritation of the throat and eyes, problems breathing ... the list goes on.

Many of us are vulnerable to worsening air quality. Children, the elderly, individuals with pre-existing respiratory or heart conditions, and anyone who works or plays outdoors are all more likely to experience annoying or dangerous symptoms thanks to pollutants and allergens. [3]

No one is immune to the effects of air pollution, and all of us will be especially vulnerable at various points in our lives. As the frequency of these events increases we need to consider not only ourselves but those around us who are at risk.

Take Action on Air Quality

Stay informed

You can keep track of air quality threats thanks to a handy tool from Health Canada. The Air Quality Health Index provides a straightforward air quality risk rating for your community. The rating is on a scale of 1 to 10: the higher the number, the greater the risk. It also provides information about precautionary measures to help keep yourself safe. Paying attention air quality helps us plan our activities to ensure the safety of ourselves and our loved ones. [13]

Reduce exposure

There are many actions we can take to reduce our exposure to pollutants in the event of poor air quality:

  • Limit outdoor activity and strenuous physical activities as much as possible. If you have difficulty breathing, reduce your activities or stop altogether.
  • Try to avoid highly polluted areas, such as high-traffic areas, where possible
  • Be aware of potential hazards in your indoor environment and try to reduce exposure. Close your windows and turn off your furnace and air conditioner if they are drawing smoke or irritants indoors. Keep indoor air cleaner by avoiding smoking or burning other materials inside. Use HEPA air filters if you can.
  • In a vehicle, keep the windows closed and set the ventilation system to recirculate.

And of course, consult your family doctor or a health-care professional if you have concerns or want more advice.

Healthy Air, Healthy Communities

We can all help improve air quality in our cities and towns by walking, biking, taking public transit, and increasing the use of hybrid and electric vehicles.

We also need to work for larger-scale change. We can support public and private efforts to:

  • Revitalize urban forests
  • Implement renewable energy
  • Make public and active transportation options more effective and accessible alternatives to driving
  • Implement stricter emissions standards for vehicles and industry
  • Develop and support clean technologies
  • Take climate change seriously when planning for the future

Taking action to improve air quality can also improve our health and well being, make our communities more liveable, and fight climate change all at the same time.


  1. Global Ambient air pollution database, by country- (update 2018) World Health Organization.
  2. Global News, March 9, 2019, Air quality statement issued for Toronto warning of ‘high-levels’ of pollution on Saturdays
  3. Climate Change and Public Health Factsheets. Government of Canada.
  4. von Schneidemesser, E. Monks, P. S., Allan, J.D., Bruhwiler L., Forster, P., Fowler, D., Lauer, A., Morgan, W. T., Paasonen, P., Righi, M., Sinderlarova, K. and Sutton, M.A. Chemistry and the Linkages between Air Quality and Climate Change. Chem. Rev. 2015, 115, 3856−3897DOI: 10.1021/acs.chemrev.5b00089
  5. Climate Change Decreases the Quality of the Air we Breathe. Center for Disease Control and Prevention, American Public Health Association, U.S Department of Health and Human Services
  6. Ambient Air Pollution: Health Impacts.World Health Organization
  7. Munn R.E., Brook J.R. Air Pollution. The Canadian Enclyclopedia.
  8. Filippidou E.C., Koukouliata A. Ozone effects respiratory system Prog Health Sci 2011, Vol 1 , No2
  9. D’Amato G, Bergmann KC, Cecchi L, Annesi-Maesano I, Sanduzzi A, Liccardi G, Vitale C, Stanziola A, D’Amato M. Climate change and air pollution – Effects on pollen allergy and other allergic respiratory diseases. Allergo J Int 2014; 23: 17-23 DOI 10.1007/s40629-014-0003-7
  10. Chemistry in Sunlight. NASA Earth Observatory
  11. Popkin, B. M., D’Anci, K. E., Rosenberg, I. H. Water, Hydration and Health Nutr Rev. 2010 August ; 68(8): 439–458. doi:10.1111/j.1753-4887.2010.00304.x
  12. Health Effects of Dust. Government of Australia, Department of Health. Health WA
  13. Health Canada Air Quality Health Index. Government of Canada
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