OUTDOOR AIR: back to diagram


Sources of Pollution
There are many different sources of outdoor air pollution, including: factories, industrial processes, resource extraction, agriculture, burning of fossil fuels, cars, long-range transport, residential wood stoves, backyard burning, as well as natural sources such as forest fires and volcanoes.

Factors that Influence Exposure
Your exposure to air pollution depends on how much time you spend outdoors and the local pollution level. People in urban areas are more likely to be exposed to pollution from traffic and nearby industry, while people in rural areas may be more exposed to pollution from wood smoke or mining activities.

The level of pollution in outdoor air is determined by a number of factors, including the amount emitted, chemical interactions, and the local landscape (hilly or flat). Weather also has an important influence:

  • Clear skies allow for a higher intensity of sunlight and UV radiation, which can increase photochemical reactions and produce higher levels of some pollutants.
  • Wind speed and direction play important roles in the dilution and dispersion of pollutants.
  • Inversions create a ‘stagnant’ stable condition in which dense cold air is trapped in a low-lying area by a warmer, less dense air mass. Inversions are commonly associated with major air pollution episodes since pollutants are unable to mix vertically and stay pooled near the ground. They can persist for hours or days and often occur during the winter.
  • Long-range transport of pollution via warm air currents can bring pollution from distant industrialized areas in the U.S. and Asia, and from southern Canada to northern areas.

 

INDOOR AIR: back to diagram


Sources of Pollution
Indoor sources of airborne pollutants include smoking, heating and cooking processes (wood fireplaces, gas stoves), off-gassing from new construction materials, furnishings and consumer products (electronics, mattresses, cleaners).

Factors that Influence Exposure
Your exposure to indoor air pollutants depends on how much time you spend indoors, and the level of pollution.

Pollution levels indoors can be higher when buildings are tightly sealed and have reduced ventilation, especially in the presence of new and synthetic building materials, new furnishings and electronics, and when wood burning appliances and certain consumer products are used.

 

DUST: back to diagram


Sources of Pollution
Chemicals and metals that bind and accumulate onto dust particles can be brought in from the outside environment on shoes and pets, or can originate from within the home via cooking, smoking, wood burning, new electronics, furnishing and other consumer goods.

Factors that Influence Exposure
Young children are most susceptible to exposure via dust, when they crawl on floors or carpets and then put their hands in their mouths.

SOIL: back to diagram

Sources of Pollution
There are many potential sources of soil contamination, they include: atmospheric deposition from industrial smoke stacks and vehicle exhaust, junk/scrap yards, coal tar pits, mine tailing wastes, landfill and hazardous waste sites, leaking underground storage tanks, oils and asphalt application to roads and parking lots, or pesticides from golf courses, lawns and agriculture. Indirectly, contaminants in soil can leach into groundwater or be absorbed by crops and vegetables.

Factors that Influence Exposure
Children up to 7 years of age are susceptible to exposure via soil ingestion due to playing on the ground and hand-to-mouth behaviour. Inhalation of dust and dermal absorption is considered minimal. Soil is more often a link in the pathway of exposure via food (outdoor air –> soil –> plant uptake –> food).

DRINKING WATER: back to diagram

Sources of Pollution
Canadian drinking water supplies are generally of excellent quality. Untreated surface or well water may be contaminated from naturally occurring deposits of metals and metalloids (lead and arsenic), leachate from nearby industrial or mining sites, or leaks from underground fuel storage tanks. In the case of treated drinking water, chlorination can lead to the formation of disinfection byproducts that are known or suspected carcinogens.

Factors that Influence Exposure
The amount of water you drink, and the amount of pollution in your water affect your level of exposure. The use of a water filter may reduce pollution levels in your water.

FOODS AND BEVERAGES: back to diagram

Sources of Pollution
Pollutants can find their way into the food chain via multiple pathways, such as atmospheric deposition from stack emissions, their release into waterways, or direct application such as pesticides or sewage sludge as fertilizer. Harvesting, transportation, preparation and packaging can also introduce pollutants. Naturally occurring chemicals, such as arsenic, are often found at normal background levels in trace amounts.

Factors that Influence Exposure
You exposure to known or suspected carcinogens via food and beverages depends on how much you eat and drink, and the level of pollutants present.