Population exposure to outdoor air pollutants (2023)

Key results

• In the most recent reporting period (2017 to 2019), 71% of Canadians lived in areas where outdoor concentrations of air pollutants were within the standards
  • This represents an improvement from 68% in the previous reporting period (2016 to 2018), mainly because air pollution concentrations in Mississauga did not exceed the standards in 2017 to 2019
  • It is also an improvement from 63% for the first reporting period (2005 to 2007)

Percentage of Canadians living in areas where outdoor concentrations of air pollutants were less than or equal to the 2020Canadian Ambient Air Quality Standards, Canada, 2005 to 2019

How this indicator was calculated

Note:With the exception of the annual standards for nitrogen dioxide and sulphur dioxide, the 2020Canadian Ambient Air Quality Standards used in the indicator use 3-year average concentrations. For this reason the bar chart portrays percentage values over 3-year periods. The annual standards for nitrogen dioxide and sulphur dioxide use a single annual concentration for the 3-year reporting period. For example, for the 2017 to 2019 reporting period, the annual concentrations for 2019 were used for the annual standards for nitrogen dioxide and sulphur dioxide.
Source:Environment and Climate Change Canada (2022) Air Quality Research Division. Health Canada (2022) Air Quality Risk Assessment Division.

The indicator uses a total of 7standards^{Footnote 3} related to 4air pollutants (fine particulate matter [PM_2.5], ground-level ozone [O₃], nitrogen dioxide [NO₂] and sulphur dioxide [SO₂]). All 7 of these standards must be met for the population of a given area to be counted as less than or equal to the standards.

During the 2017 to 2019 reporting period, Ontario, Alberta and British Columbia had the most exceedances, while Quebec, New Brunswick and Saskatchewan had a smaller number of exceedances. Newfoundland and Labrador, Prince Edward Island, Nova Scotia, Manitoba, the Northwest Territories, Yukon and Nunavut had no exceedances.^{Footnote 4} For detailed information on geographical areas where exceedances were observed, please refer to AnnexA.

Between the 2005 to 2007 and 2017 to 2019 reporting periods, the 8-hour standard for O₃ was exceeded most often. However, the proportion of the population living in areas exceeding this standard decreased from 34% in 2005 to 2007 to 17% in 2017 to 2019.^{Footnote 5}

From the 2013 to 2015 reporting period to the 2017 to 2019 reporting period, the proportion of the population living in areas exceeding the annual standard for PM_2.5 decreased from 13% to 2%. This improvement can be attributed to fewer large cities, having exceedances over the latter reporting periods; for example, no exceedances were recently reported in Montreal, Quebec City, or Hamilton. Conversely, in British Columbia, the number of communities exceeding the annual standard for PM_2.5 increased from 5 to 12 over this same period.

For the last 2reporting periods (2016 to 2018 and 2017 to 2019), the proportion of the population living in areas exceeding the 24-hour standard for PM_2.5 was, respectively, 13% and 12%. This is an increase from the 3% observed over the 2015 to 2017 reporting period. This can be attributed to the influence of smoke from large wildfires in the western United States in 2018, and in British Columbia in 2017 and 2018 that affected air quality in large communities in Alberta (Calgary, Edmonton and Red Deer), Saskatchewan (Saskatoon) and British Columbia (Abbotsford and Kelowna).

Exceedances of the annual and 1-hour standards for SO₂ had minimal influence on the indicator. High concentrations of SO₂ tend to be limited to areas near the SO₂ sources which are typically located in communities with smaller populations. Despite its small influence on the indicator, SO₂ (specifically the 1-hour standard) remains a concern because of its health impacts on populations and the environment close to sulphur-emitting facilities.

Since the 2013 to 2015 reporting period, there have been no exceedances of the annual and 1-hour standards for NO₂.

About the indicator

What the indicator measures

This indicator tracks the proportion of the Canadian population living in areas where outdoor concentrations of air pollutants were less than or equal to the 2020Canadian Air Ambient Quality Standards (CAAQS, the standards). The indicator uses the following 2020standards (see Table1 for more details).

• fine particulate matter (PM_2.5): 24-hour and annual
• ground-level ozone (O₃): 8-hour
• nitrogen dioxide (NO₂): 1-hour and annual
• sulphur dioxide (SO₂): 1-hour and annual

Why this indicator is important

Canadians are exposed to air pollutants on a daily basis and this exposure can result in adverse health effects. Exposure to some air pollutants, even at low levels, has been linked to increased heart and respiratory problems, leading to increased hospitalization, emergency room visits and premature death. The Government of Canada estimates that each year 42premature deaths per 100000Canadians can be linked to air pollution for a total of 15300premature deaths. The total economic valuation of the health impacts attributable to air pollution in Canada is $120billion per year (based on 2016currency).^{Footnote 6}

Ground-level O₃ and PM_2.5 are key components of smog and 2 of the most widespread air pollutants. Exposure to O₃ and PM_2.5, even at very low levels, has been associated with pulmonary, cardiovascular and respiratory health effects. Exposure to O₃ can cause throat irritation, coughing, shortness of breath and reduced lung function, and can also aggravate existing conditions, such as asthma or other chronic lung diseases. Exposure to PM_2.5 can lead to respiratory and cardiovascular effects, such as asthma attacks, chronic bronchitis, heart attacks as well as lung cancer.

Exposure to SO₂ and NO₂ can irritate the lungs, reduce lung function and increase susceptibility to allergens in people with asthma. Long-term exposure to NO₂ may contribute to allergies and asthma development. Fine particulate matter (PM_2.5), O₃ and NO₂ are known to have adverse health effects occurring even at low concentrations.

Besides their direct effects on human health, these pollutants also have adverse environmental impacts. NO₂ contributes to the formation of O₃ and PM_2.5, and has major impacts on acid deposition ("acid rain") and eutrophication (excessive nutrients in a body of water leading to algal blooms and low-oxygen that impact the aquatic system). Similarly, SO₂ is also a major contributor to acid deposition and contributes to secondary formation of PM_2.5. Fine particulate matter (PM_2.5) can damage vegetation and structures, and contributes to haze and reduced visibility. Ozone can also impact vegetation, decrease the productivity of some crops and may contribute to forest decline. It can also damage synthetic materials and textiles, cause cracks in rubber, accelerate fading of dyes and speed deterioration of some paints and coatings.

Improved air quality reduces heart attacks, hospital visits, allergy and child asthma attacks, and prevents lost school and work days. Cleaner air can also reduce damage to crops, forests, surface waters and infrastructure such as buildings and bridges.^{Footnote 7}

Consult the Air pollution: drivers and impacts web page for information on the impacts of air pollution on human health, the economy and the environment.

Related initiatives

This indicator tracks progress on the 2022 to 2026 Federal Sustainable Development Strategy, supporting the target: Increase the percentage of the population across Canada living in areas where air pollutant concentrations are less than or equal to the Canadian Ambient Air Quality Standards from 60%^{Footnote 8} in 2005 to 85% in 2030. The most recent data available shows that, between the 2005 to 2007 and the 2017 to 2019 reporting periods, the percentage of Canadians living in areas where outdoor concentrations of air pollutants were less than or equal to the 2020 Canadian Ambient Air Quality Standards increased from 63% to 71%.

In addition, the indicator contributes to 2 of the Sustainable Development Goals of the 2030 Agenda for Sustainable Development. It is linked to Goal11, Sustainable Cities and Communities and Target11.6, "By 2030, reduce the adverse per capita environmental impact of cities, including by paying special attention to air quality and municipal and other waste management."

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 PM_2.5, O₃, SO₂, NO₂ and VOCs at the national and regional level and at local monitoring stations.

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

TheAir pollutant emissions indicators track emissions from human activities of 6key air pollutants: sulphur oxides(SO_X), nitrogen oxides(NO_X), volatile organic compounds(VOC), ammonia(NH₃), carbon monoxide(CO) and fine particulate matter(PM_2.5). Black carbon, which is a component of PM_2.5, is also reported. For each air pollutant, data are provided at the national, provincial/territorial and facility level and by major sources.

Data sources and methods

Data sources

The indicator is calculated from air pollutant concentration data and population statistics.

The air pollutant concentration data are taken from Environment and Climate Change Canada's Canada-wide Air Quality Database The population data were retrieved from Statistics Canada's demographic statistics.

Methods

The indicator is calculated by comparing the spatially averaged pollutant concentration for each geographical area with the respective 2020Canadian Ambient Air Quality Standards (CAAQS, the standards). The total population of all geographical areas where the average concentrations for all pollutants are less than or equal to the respective standards are compared to the national population.

Recent changes

The annual standard for sulphur dioxide was included for all reporting periods, whereas in the previous iteration this standard was considered only for the 2015 to 2017 and the 2016 to 2018 reporting periods. Similar to the 1-hour standard for sulphur dioxide, only population data within the 2 km boundary of the monitoring station were used for the annual standard, whereas in the previous iteration all of the population data pertaining to the geographical area was used.

A data completeness criteria for the ozone concentration calculation was changed. Daily maximum 8-hour average concentrations were considered over the full year, instead of the period from April 1 to September 30 as in the last iteration.

Only stations that are selected by provinces and territories for reporting on CAAQS achievement under the Air Quality Management System are used in the calculation, whereas all stations reporting to Canada-wide Air Quality Database were used in the last iteration.

Due to the methodology changes listed above, the results for all reporting periods have been recalculated and show slight differences with the values released previously.

Caveats and limitations

From 2005 to 2019, approximately 62% of the population lived in areas covered by selected air quality monitoring stations that meet the data completeness criteria. Refer toAnnex Bfor a list of geographical areas used in the indicator. The indicator assumes that the remainder of the population lives in areas where outdoor concentrations of ozone, fine particulate matter, sulphur dioxide and nitrogen dioxide are less than or equal to their 2020 standards.^{Footnote 11}Populations in northern regions of the country have less coverage, as monitoring stations tend to be situated near urban areas with a higher population density.

Resources

References

Canadian Council of Ministers of the Environment (2012) Guidance document on achievement determination for Canadian Ambient Air Quality Standards for fine particulate matter and ozone (PDF; 264kB). Retrieved on November22,2022.

Canadian Council of Ministers of the Environment (2014) Air Quality Management System. Retrieved on November22,2022.

Canadian Council of Ministers of the Environment (2017) State of the air. Retrieved on November22,2022.

Canadian Council of Ministers of the Environment (2019) Guidance document on air zone management (PDF;225kB). Retrieved on November22,2022.

Canadian Council of Ministers of the Environment (2020) Guidance document on achievement determination for Canadian Ambient Air Quality Standards for nitrogen dioxide (PDF; 616kB). Retrieved on November22,2022.

Canadian Council of Ministers of the Environment (2020) Guidance document on achievement determination for Canadian Ambient Air Quality Standards for sulphur dioxide (PDF; 586kB). Retrieved on November22,2022.

Environment and Climate Change Canada (2022) National Air Pollution Surveillance Program. Retrieved on November22,2022.

Government of Canada (2021) Health effects of air pollution. Retrieved on November22,2022.

Related information

Air pollution: drivers and impacts

Canadian Smog Science Assessment Highlights and Key Messages

Smog: causes and effects

Annex A. Geographical areas with exceedances from the standards for the 2017-2019 reporting period

Annex B. Geographical areas used to calculate the indicator

Annex A.Geographical areas with exceedances from the standards for the 2017-2019 reporting period

Note: With the exception of the annual standard for nitrogen dioxide and sulphur dioxide, the 2020Canadian Ambient Air Quality Standards used in the indicator use 3‑year average concentrations. For this reason the table portrays percentage values over 3-year periods. The annual standards for nitrogen dioxide and sulphur dioxide use a single annual concentration for the 3-year reporting period. For example, for the 2017to 2019 reporting period, the annual concentrations for 2019 were used for the annual standards for nitrogen dioxide and sulphur dioxide.
Source: Environment and Climate Change Canada (2022) Air Quality Research Division. Health Canada (2022) Air Quality Risk Assessment Division.

Annex B.Geographical areas used to calculate the indicator