Air pollution: drivers and impacts

Air pollutionFootnote 1 can affect Canadians' health, the environment, buildings, structures and the economy. Air pollution problems such as smogFootnote 2 and acid rain result from the presence of and interactions between various pollutants released to the atmosphere through natural processes and human activities.

Natural sources of air pollution include forest fires, volcanoes and emissions of volatile organic compounds (VOCs) from vegetation. Human sources of air pollution include activities that rely on carbon-based fuels (for example, transportation, off-road vehicles and mobile equipment, electric utilities), industrial processes such as oil and gas production, as well as certain products, such as paints and solvents.

Key drivers of air pollution

Outdoor air pollutant concentrations can be influenced by many factors. These include the quantity of air pollutants released by sources, the distance from the sources, and meteorological conditions such as air temperature, the stability of the air, wind speed and direction. Some air pollutants can be carried by the wind and affect the air quality in locations which are hundreds to thousands of kilometres away from the sources.

The growth in Canada's population and economy increases the demand for the production and delivery of goods and services, transportation and housing. Most of the energy used to meet this demand still comes from fossil fuels, which impacts the quality of the air we breathe. Economic growth includes a growing demand for Canadian exports (especially from the oil and gas industry) that also results in releases of air pollutants.

Despite this growth in demand, the quantity of emissions of many air pollutants has generally decreased in Canada in the past two decades. These reductions were achieved through various means, including the implementation of regulations, non-regulatory instruments, and technological improvements for transportation vehicles and industrial processes. The adoption of more environmentally sustainable practices by consumers and industry, such as using public transit and carpooling, and optimizing production processes to reduce energy use, have also contributed to the decrease.

Consult the Air pollutant emissions indicators for more information on the main sources contributing to Canada's emissions of key air pollutants: sulphur oxides (SOX), nitrogen oxides (NOX), volatile organic compounds (VOCs), ammonia (NH3), carbon monoxide (CO) and fine particulate matter (PM2.5).

Key impacts of air pollution

Human health impacts

  • Globally, exposure to air pollution is a major cause of illness and even death. As a result of exposure, an estimated 4.2 million premature deaths occur every year from outdoor air pollution.Footnote 3 In Canada, air pollution is linked to an estimated 15 300 premature deaths every year.Footnote 4 
  • Exposure to NOX and SOX can irritate the lungs, reduce lung function and increase susceptibility to allergens in people with asthma. Both NOX and SOX are also precursors of PM2.5, and contribute to the formation of smog and acid rain.
  • Fine particulate matter (PM2.5) and ground-level ozone (O3) are the main components of smog and they have been associated with eye, nose and throat irritations, shortness of breath, exacerbation of respiratory conditions and allergies, chronic obstructive pulmonary disease and asthma, increased risk of cardiovascular disease and premature death.Footnote 5 The young, the elderly, those with acute illnesses and those living near cities are at greater risk.
  • Carbon monoxide (CO) is a product of incomplete combustion of hydrocarbon-based fuels. It can have a significant impact on human health by entering the blood stream through the lungs inhibiting the blood's capacity to carry oxygen to organs and tissues. CO is particularly harmful to persons with heart disease and individuals with respiratory conditions. It can also affect healthy individuals by reducing exercise capacity, visual perception, manual dexterity, learning functions, and ability to perform complex tasks.Footnote 6
  • Ammonia (NH3) is a colourless gas mostly generated from livestock waste management and fertilizer production. It is poisonous if inhaled in great quantities and is irritating to the eyes, nose, and throat in lesser amounts.Footnote 7 
  • Short-lived climate pollutants (SLCPs) are both air pollutants and greenhouse gases that have near-term warming impact on climate and can affect air quality. SLCPs include black carbon (a component of PM2.5), methane, O3, and hydrofluorocarbons (HFCs). Global action on carbon dioxide and SLCPs together is needed to meet the temperature goals in the Paris Agreement.

Environmental impacts

  • Nitrogen oxides (NOX) and SOX are major contributors to acid rain. Acid rain can accelerate the degradation of certain rocks, such as limestone and sandstone. It affects soils and water bodies, and stresses both vegetation and animals. The interactions between acid rain, ultraviolet (UV) radiation and climate change can magnify the impacts of acid rain.Footnote 8 Footnote
  • Emissions of mercury and other hazardous pollutants work in synergy with sulphur dioxide (SO2) and NOX to worsen the harmful effects of acid deposition on fish and wildlife. Increasing acidity of water bodies increases the rate of conversion of mercury into its more toxic form methyl mercury (MeHg) that can build up in fish and shellfish and be ingested by humans and wildlife.Footnote 10  
  • Particulate matter (PM which includes PM2.5) taken up by plants from the soil can reduce plant growth and productivity by interfering with photosynthesis and can cause physical damage to plant surfaces.Footnote 9 
  • Ground-level ozone (O3) can reduce the growth and productivity of some crops, injure flowers and shrubs and may contribute to forest decline in some parts of Canada.Footnote 9  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 10 
  • Ammonia (NH3) can contribute to the build up of nitrogen and excessive plant and algal growth in aquatic systems.Footnote 7  As the plant material decays, it can reduce the amount of oxygen available for fish and other aquatic animals and degrade the quality of the water. 

Economic impacts

  • Emissions of NOX, SOX and PM that contribute to acid rain can lead to the premature wearing of materials and building soiling. This can lead to increased maintenance costs for monuments, buildings and other infrastructure. While there has been little research into the economic costs of acid rain in Canada, the estimated costs of building soiling and premature wearing due to acid rain and PM could possibly be significant.Footnote 11  
  • The health effects of PM2.5 and O3 can impose economic costs from lost productivity, increased need for medical care, decreased quality of life and increase the risk of premature death. The total economic valuation of the health impacts attributable to air pollution in Canada is $120 billion per year.Footnote 4 
  • Increased O3 levels also reduce the growth of crops, plants and trees, leading to economic losses in agriculture and forestry. This costs Canadian farmers millions of dollars in lost production each year.Footnote 12  
  • Smog can accelerate the discolouration, fading and tarnishing of materials (for example, rubbers, textiles, surface coatings). This increases the rate at which they need to be replaced or cleaned.Footnote 9

Ways to tackle air pollution

Air pollution is a global issue that affects everyone and that results from decisions and actions taken by individuals and government. We all have a part to play in reducing it.


Releasing pollutants into the atmosphere is subject to a number of regulations in Canada. Specifically, the Government of Canada, under the authority of the Canadian Environmental Protection Act, 1999 (the act) develops and implements regulations to help reduce overall levels of air pollution by limiting the amount of pollutants that are released into the air each year.

For example, the Government of Canada has put in place regulations to phase out coal-fired electricity, adopted the most stringent national standards in the world for air pollutant emissions from new cars and light trucks and put a price on carbon pollution that is creating incentives for industry to invest in cleaner technologies.

In 2016, as part of the federal government's contribution to the implementation of the Air Quality Management System, the Government of Canada introduced the Multi-sector Air Pollutants Regulations. This is Canada's first ever mandatory national air pollutant emissions standards for major industrial facilities. The federal government also published a suite of non-regulatory instruments to reduce air pollutants from a number of industrial sectors and equipment types. The Government of Canada continues to work with provinces, territories and stakeholders to set more stringent Canadian Ambient Air Quality Standards (CAAQS, the standards) to drive air quality improvements across the country. More stringent standards for PM2.5 and O3 have been in effect since 2015 and 2020 respectively. A new standard for ozone will come into effect in 2025 (it was established in 2019). Standards for sulphur dioxide (SO2) and nitrogen dioxide (NO2) were established in 2017 for 2020 and 2025. The PM2.5 standard is currently under review. The regulations and standards will contribute to reducing emissions of air pollutants and further protect human health and the environment for Canadians.

Regulations specific to air pollutants under the Canadian Environmental Protection Act, 1999 include, but are not limited to, the following:

All regulations administered under the act are available in the Canadian Environmental Protection Act Registry.

To learn more about the expected impact of regulations developed by the Government of Canada, consult the Regulatory Impact Analysis StatementFootnote 13  that accompanies each regulation. The statements outline the reasoning behind the development of a particular regulation, its objectives, and its expected costs and benefits. They also include details about consultations that were conducted and about how the government intends to track the performance of the regulation.

In addition to the above, the Government of Canada in collaboration with partners within Canada and internationally, develops the Federal Sustainable Development Strategy. The Strategy is the Government's primary vehicle for sustainable development planning and reporting. It sets out sustainable development priorities, establishes goals and targets, and identifies actions to achieve them, including actions related to tackling air pollution. Bilateral and international cooperation, including under the Canada-United States Air Quality Agreement and the United Nations Economic Commission for Europe’s Convention on Long-range Transboundary Air Pollution, is also an important component of Canada’s approach for improving air quality and key to advancing Canada’s air quality objectives.


Below are some actions you can take to help reduce overall air pollution levels:

  • When possible, instead of taking a car, use public transportation, walk or ride a bicycle when and where it is safe to do so
  • Consider fuel efficiency when buying a vehicle. Look for alternatives to fossil fuel-powered vehicles such as hybrid or zero-emission vehicles
  • Keep all gasoline vehicles well maintained to ensure they operate efficiently
  • Choose to use a push-type lawnmower instead of one that runs on gasoline
  • Reduce energy use by making your home more energy efficient
    • Keep gas-, oil- and wood-burning stoves, heaters and appliances in good condition or replace them with newer cleaner technologies
    • Turn off the lights when leaving a room and unplug electronics when not in use
  • Rethink consumer behaviors by differentiating your needs and your wants
  • Plant trees and a variety of vegetation to improve air quality – this will also serve to increase the urban forest canopy, biodiversity, and provide shade

For more tips on what you can do, visit What you can do to improve air quality.

To reduce your exposure to air pollution and its potential health effects, you can:

  • Check the Air Quality Health Index forecast for 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
  • Take special precautions if there is smoke from a wildfire affecting your community
  • Keep your medication with you if you suffer from heart or respiratory problems
  • Talk to your family doctor or a health care professional if you have concerns about your health or the health of a family member

Related indicators

The Air health trends indicator provides an overview of the public health impacts attributable to outdoor air pollution in Canada.

The Air quality indicators track ambient concentrations of PM2.5, O3, SO2, NO2, and VOCs at the national and regional level and at local monitoring stations.

The International comparison of urban air quality indicators present and compare the air quality in selected Canadian urban areas with a population greater than one million to the air quality in selected international urban areas having comparable data.

The Air pollutant emissions indicators track emissions from human activities of 6 key air pollutants: SOX, NOX, VOCs, NH3, CO and PM2.5. Black carbon, which is a component of PM2.5, is also reported. For each air pollutant, data are provided at the national, provincial/territorial and facility level and by major source.

The International comparison: air pollutant emissions in selected countries indicators compares Canada's emissions of 5 key air pollutants with those of top member countries of the Organisation for Economic Co-operation and Development.

The Human exposure to harmful substances indicators track the concentrations of 4 substances (mercury, lead, cadmium and bisphenol A) in the Canadian population.Footnote 14

The Emissions of harmful substances to air indicators track human-related emissions to air of 3 toxic substances, namely mercury, lead and cadmium and their compounds. For each substance, data are provided at the national, regional (provincial and territorial) and facility level and by source. Global emissions to air are also provided for mercury.

The Population exposure to outdoor air pollutants indicator tracks the proportion of the Canadian population living in areas where outdoor concentrations of air pollutants are less than or equal to the 2020 Canadian Air Ambient Quality Standards.

Other information

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