Common Air Pollutants


There are six types of common air pollutants that are measured frequently in Canada. These pollutants are: particulate matter (PM), volatile organic compounds (VOCs), nitrogen oxides (NOx), sulphur oxides (SOx), carbon monoxide (CO) and ground-level ozone (O3).

Particulate Matter

There are two kinds of particulate matter (PM): respirable particulate matter and fine particulate matter. Respirable particulate matter, also known as PM10, represents the larger particulates or those with a diameter of less than 10 micrometers. Fine particulate matter, also known as PM2.5, represents the smaller particulates or those with a diameter of less than 2.5 micrometers. The graph below shows how both respirable PM and fine PM have been decreasing in Canada since 1990.

Volatile Organic Compounds

These organic chemicals (VOCs) have a high vapour pressure at normal room temperatures. This means that they evaporate at room temperatures, exposing humans and animals to potentially harmful chemicals. VOCs are most frequently released into their atmosphere by solvents, paints, burning fossil fuels, smoking cigarettes and through aerosol sprays. VOCs are also a precursor to smog.

Nitrogen Oxides

A major source of nitrogen oxides (NOx) is sourced from the burning of fossil fuels. While most emissions come from the transportation sector, fuels burned for energy production are also a major contributor in Canadian NOx emissions. Nitrogen oxides can harm the environment as they are a major contributor to acid rain.

Sulphur Oxides

Sulphur oxides (SOx) are released into the atmosphere anthropologically (through manufacturing) and naturally (through volcanoes). Sulphur oxides are a major contributor to acid rain, which increases the acidity of soil and bodies of water, severely affecting the suitability of habitats for both plant and animal life.

Carbon Monoxide

Carbon monoxide, often called ‘the silent killer’ is odourless, colourless and tasteless. In high enough concentrations (at 35 ppm) it is toxic to humans. It is produced through the partial oxidization of compounds that contain carbon. An example of how carbon monoxide gets produced is through burning coal in a closed space. In this case, there is insufficient oxygen to produce carbon dioxide, so carbon monoxide is the result. Carbon monoxide is also produced naturally, through forest fires and volcanoes for example.

Ground-level Ozone

Ground level ozone (O3) is formed when volatile organic compounds and nitrogen dioxides react in direct sunlight. Like many air pollutants, ground level ozone can be carried by wind to locations far away from where it was produced. The effects of being exposed to high concentrations of this contaminant include damage to lung tissue and decreases in lung functionality.