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Air Pollutants

Last updated on March 26, 2019

Air pollutants are any gas, liquid or solid substance that have been emitted into the atmosphere and are in high enough concentrations to be considered harmful to the environment, or human, animal and plant health.

The most serious threat to our health come from particulate matter and ground-level ozone pollutants, the key ingredients of smog.

Learn more about common pollutants.

Types of Pollutants

There are two types of pollutants:

  1. Primary pollutants: are emitted directly into the air
  2. Secondary pollutants: are formed in the air, when they react with other pollutants

Ground-level ozone is an example of a secondary pollutant that forms when nitrogen oxides (NOx) and volatile organic compounds (VOCs) react in the presence of sunlight.

Pollutant Sources

We come in contact with many kinds of air pollutants every day, both natural and man-made.

Smoke from wood stoves or backyard burning, motor vehicle exhaust, and dust from construction are pollutant mixtures that affect air quality in our neighbourhoods and communities and inside our homes.  

Forest fire or ground-level ozone smoke can cover an entire region. Long-lasting pollutants can contribute to serious global problems, such as ozone depletion and climate change.

  • Point source: a single, stationary source of pollution, such as an industrial facility, that typically operates under some kind of government authorization (e.g., a permit, approval or regulation) 
  • Non-point source: includes stationary and mobile sources that are individually small compared to point sources, but collectively large, such as wood stoves, motor vehicles and lawnmowers, and includes sources whose emissions are spread out over a broad area, such as prescribed burning

Harmful Effects

Pollutants can be dangerous to our health when we are exposed to it for a long time. Health effects can last for a short while (e.g., coughing) or become a long-term problem (e.g., lung and heart disease, cancer). Pollution can also cause death.

The young, the elderly and those with pre-existing heart or lung disease are the most sensitive to the effects of air pollution.