Drivers and Impacts of Air Pollution
Air pollutants can affect Canadians' health, the natural environment and the economy.
Air pollution is broadly defined as the presence in the air of any pollutant (or substance) that directly or indirectly endangers, interferes with, causes damages, degrades or alters human health, animal health, the environment, or ecosystems. Individual pollutants differ from one another in their chemical composition, reactions with other chemicals, sources, persistence, ability to travel through the atmosphere, and impacts.
Criteria air contaminants (CACs), which are the focus of this page, refer to a group of pollutants that include sulphur oxides (SOx), nitrogen oxides (NOx), particulate matter (PM), volatile organic compounds (VOC), carbon monoxide (CO) and ammonia (NH3). In addition, ground-level ozone (O3) and secondary particulate matter are often referred to among the CAC because they both are by-products of chemical reactions between the CACs that take place in the atmosphere.
Overview of the key drivers of air pollution
Air pollution is the result of human activities such as the burning of fuels for transportation (e.g., cars and trucks), electricity generation and heating, industrial processes, and the use of certain products (e.g., paints and solvents). It also caused by natural sources (such as emissions of volatile organic compounds from vegetation).
In 2013, open sources (mostly dust from paved and unpaved roads and construction operations) were the largest source of fine particulate matter (PM2.5), making up 79% of total emissions. In the case of NH3 emissions, open sources (mostly from agriculture) represented 94% of the total in 2013. That same year, industrial sources were the largest contributor to emissions of SOx (69%) and VOCs (37%). Finally, transportation and off-road sources were the most important emitters of NOx (55%) and CO (59%).Footnote 
A wide variety of factors influence air pollution emissions in Canada. These include Canada's physical geography, demographic changes in its population and economic growth. Canada has a highly variable climate. This contributes to relatively higher energy use for space heating and cooling of buildings compared to other industrialized countries. Canada is large and sparsely populated, which leads to longer travel times and higher demand for transportation than in smaller and/or more densely populated countries. In addition, Canada experienced faster than average population and economic growth relative to other developed countries between 2000 and 2012. Other important factors influencing air pollution include the adoption of more efficient practices or equipment by consumers and industry. Examples include how people commute to work, where businesses decide to locate their manufacturing facilities and whether they choose to buy or manufacture more energy-efficient products.
Despite these challenges, emissions of air pollutants have generally decreased in Canada over the past two decades, as technological improvements and regulations have been adopted and implemented in various economic sectors.
Overview of the key impacts of air pollution
- Ground-level O3 can significantly impact vegetation and reduce the productivity of some crops. It can also injure flowers and shrubs and may contribute to forest decline in some parts of Canada.Footnote  Ecosystem changes can also occur, as plant species that are more resistant to O3 can become more dominant than those that are less resistant.Footnote 
- The impacts of PM on vegetation are dependent upon its chemical constituents and particle size. Plant response to PM is largely due to the resultant changes in soil chemistry rather than direct deposition on the plant. Various PM constituents taken up by the plant from the soil can reduce plant growth and productivity. PM can also cause physical damage to plant surfaces via abrasion.Footnote 
- NOx and SO2 can become acidic gases or particulates, and cause or accelerate the corrosion and soiling of materials. Together with NH3, they are also the main precursors of acid rain. Acid rain affects soils and water bodies, and stresses both vegetation and animals.Footnote 
- CO can have a significant impact on human health. It enters the bloodstream through the lungs and forms carboxyhemoglobin, a compound that inhibits the blood's capacity to carry oxygen to organs and tissues. Persons with heart disease are especially sensitive to CO poisoning. Infants, elderly persons and individuals with respiratory diseases are also particularly sensitive. CO can affect healthy individuals, impairing exercise capacity, visual perception, manual dexterity, learning functions and ability to perform complex tasks.Footnote 
Human health impacts
- PM2.5 and ground-level O3 can affect human respiratory and cardiovascular systems. The young, the elderly and those with acute illnesses are at greater risk of such effects. PM2.5 and ground-level O3 have been associated with eye, nose and throat irritation, shortness of breath, exacerbation of respiratory conditions, chronic obstructive pulmonary disease and asthma, exacerbation of allergies, increased risk of cardiovascular diseases and premature death.Footnote  In 2013, 7.9% of Canadians 12 years and older had been diagnosed with asthma by a health professional. This rate did not significantly change from 2003 to 2013.Footnote 
- Impacts range from minor breathing problems to premature death. The more common effects include changes in breathing and lung function, lung inflammation, and irritation and aggravation of existing heart and lung conditions (e.g., asthma, emphysema and heart disease).
- Negative health effects increase as the concentrations of pollutants in the air increases. Even modest increases in concentration (e.g., PM2.5 and O3) can cause small but measurable increases in emergency room visits, hospital admissions and premature death.Footnote 
- The health effects of PM2.5and ground-level O3 may reduce work attendance and overall participation in the labour force. In terms of increased health care costs, missed days of work and reduced worker productivity, it is estimated that air pollution costs Canadians and the Canadian economy billions of dollars per year.Footnote 
- Increased O3 levels also reduce the growth of crops, plants and trees, leading to economic losses in agriculture and forestry. For example, the impacts of ozone on agriculture are known to cost Canadian farmers millions of dollars in lost production each year.Footnote 
- SmogFootnote  can lower the enjoyment that Canadians and tourists derive from experiencing our natural habitat because it can impair visibility of their surroundings and scenic locations. It can also impact our built environment by accelerating the discolouration, fading, or tarnishing of materials and increasing the rate at which they need to be replaced or cleaned.Footnote 
How can we help?
To help reduce overall air pollution levels:
- When possible, use public transportation instead of your car. You could also walk or ride your bicycle, when and where it is safe to do so.
- Look for alternatives to fuel-powered machines and vehicles. Try a rowboat or sailboat instead of a motorboat or a push-type lawnmower instead of one that runs on gasoline.
- Consider fuel efficiency when you buy a vehicle. Keep all vehicles well maintained.
- Reduce energy use in your home. Learn more about alternative energy resources.
- Do not burn leaves, branches or other yard wastes.
To reduce your exposure to air pollution and its potential health effects:
- Check the Air Quality Health Index (AQHI) in your community and adapt your schedule accordingly.
- Avoid or reduce strenuous outdoor activities when smog levels are high. Consider indoor activities instead.
- Avoid or reduce exercising near areas of heavy traffic, especially during rush hour; and
- Talk to your family doctor or health care professional if you have concerns about your health or health of a family member.
The government of Canada is also taking action to help reducing the overall levels of air pollution. The release of air pollutants in the atmosphere is subject to a number of regulations under the Canadian Environmental Protection Act (1999). These regulations limit the amount of pollutants that are released in the air each year.
To learn more about the expected impact of regulations developed by the Government of Canada, consult the Regulatory Impact Analysis Statement (also known as a RIAS) that accompanies each regulation. The RIAS outlines the reasons behind the development of a particular regulation, its objectives and its expected costs and benefits. The RIAS also includes details about consultations that were conducted and about how the government intends to track the performance of the regulation.
- Air Health Indicator
- Air Pollutant Emissions
- International Comparison of Air Pollutant Emissions
- Levels of Human Exposure to Harmful Substances
- Releases of Harmful Substances to the Environment
- Environment Canada – Air
- Environment Canada – Criteria Air Contaminants and Related Pollutants
- Environment Canada – Air Pollutant Emission Inventory
- Health Canada – Air Pollution and Health
- Public Health Agency of Canada – Climate change, air contaminants, and your health
- Government of Canada – Air Quality
Regulations specific to air pollutants under the Canadian Environmental Protection Act, 1999 (CEPA) include, but are not limited to, the following:
- Volatile Organic Compound (VOC) Concentration Limits for Automotive Refinishing Products Regulations (amended 2010)
- Volatile Organic Compound (VOC) Concentration Limits for Architectural Coatings Regulations (amended 2009)
- Heavy-duty Vehicle and Engine Greenhouse Gas Emission Regulations (2013) (2013)
- Marine Spark-Ignition Engine, Vessel and Off-Road Recreational Vehicle Emission Regulations (amended 2011)
- Off-Road Compression-Ignition Engine Emission Regulations (amended 2012)
- Off-Road Small Spark-Ignition Engine Emission Regulations (amended 2012)
- On-Road Vehicle and Engine Emission Regulations (amended 2014)
- Passenger Automobile and Light Truck Greenhouse Gas Emission Regulations (amended 2014)
- Benzene in Gasoline Regulations (amended 2011)
- Contaminated Fuel Regulations (1991)
- Gasoline and Gasoline Blend Dispensing Flow Rate Regulations (2000)
- Gasoline Regulations (amended 2010)
- Renewable Fuels Regulations (amended 2013)
- Sulphur in Diesel Fuel Regulations (amended 2012)
- Sulphur in Gasoline Regulations (amended 2009)
- Products Containing Mercury Regulations (2014)
- Secondary Lead Smelter Release Regulations (1991)
- Export of Substances on the Export Control List Regulations (2013)
- Pulp and Paper Mill Effluent Chlorinated Dioxins and Furans RegulationsFR (1992)
- Footnote 1
Environment Canada (2015) Air Pollutant Emission Inventory Report 1990-2013.
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Environment Canada (2012) Canadian Smog Science Assessment – Highlights.
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Natural Resources Canada (2014) Canada in a Changing Climate: Sector Perspectives on Impacts and Adaptation.
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Statistics Canada (2013) Health Fact Sheets: Asthma, 2013, 82-625-X.
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The term "smog" was first coined more than three decades ago to describe a mixture of smoke and fog in the air. It is now considered to include PM and O3 and the precursor pollutants SO2, NOx, VOCs and NH3.
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