In March 2011, the Canadian Institute for Health Information (CIHI) released a report, Urban Physical Environments and Health Inequalities, which examines outdoor air pollution and heat extremes for their impact on the health of those with low socio-economic status (SES).
Air Quality & Health
Outdoor air pollution has a substantial impact on human health. In 2004, research conducted by Health Canada and Environment Canada attributed 5,900 non-traumatic deaths per year in eight Canadian Cities (Vancouver, Calgary, Windsor, Hamilton, Toronto, Ottawa, and Quebec City) to outdoor air pollution (Judek, Jessiman & Stieb, 2004). The researchers found that the five common air pollutants contributed to between 7% and 10% of all non-traumatic deaths in the four Ontario cities included the study. One third of the 5,900 deaths were associated with acute impacts associated with short-term exposures while two thirds were associated with chronic disease resulting from long-term exposure to one pollutant in the mix, fine particulate matter (PM2.5) (Judek, Jessiman & Stieb, 2004).
Air quality can vary as much within a single city as it does across multiple urban areas because of localized emission sources such as high volume traffic corridors, major industrial facilities, and stationary motor-related facilities (e.g. truck depots) (Jerret 2007). Studies conducted by Finkelstein in Hamilton (2003) and Cakmak in Montreal (2006) have found higher rates of health impacts among lower income populations exposed to higher levels of air pollution. The CIHI set out to explore the contribution of air pollution associated with traffic corridors and industrial point sources to health inequalities among Canadians.
Traffic Corridors, Air Quality & Health Socio-Economic Status
The CIHI selected five Canadian cities – Vancouver, Edmonton, Toronto, Ottawa and Montreal – for case studes to further examine the relationship between major roadways and socio-economic status. Within each City, a section of a major highway was selected and the socio-economic status of residential areas within 200 metres of that highway section was examined using a Geographical Information Systsm (GIS). For the most part, the analyses of the selected Cities demonstrated that the low income neigbhourhoods are more likely to be located within 200 metres of major highways than the high income neighbourhoods. This pattern was clearest in the streches of highway selected for Montreal and Toronto, but did not in Edmonton where the relationship between socio-economic status and residential proximity to a major roadway was reversed (CIHI, 2011).
Industrial Point Sources, Air Quality & Socio-Economic Status
The CIHI also examined the socio-economic status of residential areas within 0.5, 1.0, 1-2, and greater than 2, kilometres of pollution-emitting facilities across Canada using the National Pollutant Release Inventory (NPRI). This analysis found that about 16% of the 21 million people living in Canada’s urban regions live within 1 kilometre of a pollution-emitting facility that reports one of the five common air pollutants to NPRI. When the socio-economic status of those residents was examined, CIHI found that people from the low income neighbourhooods were more likely be located within 1 kilometre of these facilities (i.e., 25% chance) than residents from high income neighbourhoods (i.e., 7% chance).
When CIHI examined hospital admissions for circulatory and respiratory diseases for people based on their proximity to the pollution-emitting facilties, it found that hospital admissions rates for both conditions were 12 and 20 per cent higher respectively in areas within 0.5 of a pollution-emitting facility than in residential areas that were more than 2 kilometres away. It also found however, that rates of hospitalization for these two diseases significantly decreased with distance from the pollution-emitting source only for those residents with the lowest income levels.
These results suggest that some of the health effects associated with residential proximity to point sources may be related to the income and education levels of people who live in closer to these pollution sources. They also suggest that people with low incomes may be more vulnerable to the negative health effects of air pollution, than people with higher incomes.
- Cakmak et al. 2006. “Respiratory Helth Effects of Ari Pollution Gases: Modification by Education and Income.” Archives of Environmental & Occupational Health. 61,
- Canadian Institute for Health Information (CIHI). 2011. “Urban Physical Environments and Health Inequalities”. (67 pages)
- Finkelstein et al. 2003. “Relation Between Income, Air Pollution and Mortality: A Cohort Study” CMAJ. 169, 5
- Jerret at al. 2007. MOdelign the intraurban Variability of Ambient Traffic Pollution in Toronto, Canada. Journal of Toxicology & Environmental Health. Part A 70, 304.
- Judek, Jessiman & Stieb. 2004. Estimated Number of Excess Deaths in Canada Due to Air Pollution, Health Canada. Environment Canada.