Common Air Pollutants

Air pollutants affect human health and the environment and hamper our ability to see very far.

It cuases both local and global impacts evel with ground-level ozone and wood smoke, and at a global level with climate change and depletion of the ozone layer.

Health effects caused by air pollution can be short or long term. Pollution can also cause death. An air pollutant can become dangerous to our health when we are exposed to it for a long time, as well as when we breathe in a large amount of it. 

Significant Air Pollutants

Air pollutants that pose the most serious local threat to our health are particulate matter and ground-level ozone — the key ingredients of smog. They mainly affect the lowest part of the atmosphere, which holds the air we breathe. Particulate matter is a significant problem in rural areas because of wood burning.

Particulate Matter (PM)

Particulate matter is the tiny solid or liquid particles that float in the air. Some particles are large or dark enough to be seen as smoke, soot or dust. Others are so small that they can only be detected with an electron microscope.

Types of particulate matter:

  1. Primary:
    1. Emitted directly into the atmosphere by wood and fossil fuel burning
    2. Includes pollen, spores and road dust
  2. Secondary:
    1. Formed in the atmosphere through chemical reactions involving nitrogen dioxide, sulphur dioxide, volatile organic compounds and ammonia

Particulate matter is measured in microns (one millionth of a metre). PM can make lakes and other sensitive areas more acidic, causing changes to the nutrient balance and harming aquatic life.


Description: particulate matter less than 10 microns and invisible to the naked eye and small enough to inhaled into our nose and throat

Sources: Come from road dust;, road construction, mixing and applying fertilizers/ pesticides, forest fires

Health impact: coarse particles irritate the nose and throat, but do not normally penetrate deep into the lungs.

Environmental impact: PM is the main source of haze that reduces visibility. It takes hours to days for PM10 to settle out of the air.


Description: Particulate matter that measures 2.5 microns and less. It can travel deep into the lungs and become lodged there causing heart and lung disease and premature death

Sources: Combustion of fossil fuels and wood (motor vehicles, woodstoves and fireplaces), Industrial activity, Garbage incineration, Agricultural burning

Health impact: Fine particles are small enough to make their way deep into the lungs. They are associated with all sorts of health problems — from a runny nose and coughing, to bronchitis, asthma, emphysema, pneumonia, heart disease, and even premature death.

Environmental impact: PM2.5 is the worst public health problem from air pollution in the province, and because of its small size, takes significantly longer than PM10 to settle out of the air.

Ground-Level Ozone (O3)

Description: Ground-level ozone is formed by the reaction of volatile organic compounds (VOCs) and nitrogen oxide (NO2) in sunshine and warm temperatures. When the air is stagnant, the ozone will build up. It’s a blueish gas with a noticeable odour.

Sources: Ozone is a secondary pollutant formed as described above.

Health impact: Even small amounts of ozone can irritate the eyes, nose, and throat. Ozone can also reduce lung function, irritate the lung airways, and make them red and swollen. People with heart or lung problems are most at risk, but even healthy people who are active outdoors can be affected when ozone levels are high. Ozone exposure can contribute to asthma, and reduced resistance to colds and other infections.

Environmental impact: Damaged plants and trees may produce lower yields and lung and respiratory damage in animals.

Other Pollutants

Types of pollutants include: particulate matter (PM), sulphur oxides (SOx), nitrogen oxides (NOx), volatile organic compounds (VOCs), carbon monoxide (CO) and ammonia (NH3), persistent organic pollutants (POPs) like dioxins and furans, and heavy metals like mercury. 

Description: Most of these pollutants come from combustion and industrial processes or the evaporation of paints and common chemical products.

Health impacts: The health impacts of these pollutants are varied. Carbon monoxide is fatal at high concentrations, and causes illness at lower concentrations. Dioxins and furans are among the most toxic chemicals in the world.

Environmental impact: While some of these pollutants have local impact on the environment (lead) or are relatively short lived (NO2), some are long lived (POPs) and can travel the world on wind currents in the upper atmosphere. Sulphur dioxide (SO2), can transform in the atmosphere to sulphuric acid, a major component of acid rain.

Vehicle Pollutants

Pollutant Name


Air Toxics Vehicles emit toxic air pollutants such as benzene, 1,3-butadiene, acrolein, formaldehyde and polycyclic aromatic hydrocarbons (PAH). Some of these components are VOCs, while others are contained in particles.
Carbon Monoxide (CO) CO results from the incomplete combustion of vehicle fuels. Gasoline engines emit a higher proportion of CO than diesel engines, due to the lower combustion temperature.
Coolants Older vehicles may have air conditioning systems using Freon, an ozone depleting substance, as a refrigerant. This Freon could be emitted through leaks, or during repairs. Newer vehicles use non-ozone-depleting coolant. The coolants in newer vehicles are still pollutants as they act as greenhouse gases.
Nitrogen oxides (NOx) These are created during combustion. Vehicle engines burn a small amount of the nitrogen present in the air plus nitrogen compounds found in vehicle fuels. Diesel engines produce much larger amounts of NOx than gasoline engines due to the higher combustion temperatures.
Other Emissions The production, distribution, storage and marketing of transport fuels also cause air pollution emissions. An example is the emission of hydrocarbon vapours during refuelling of vehicles.
Sulphur Dioxide (SO2) SO2 is emitted from the combustion of sulphur contained in the fuel. Most SO2 is from diesel engines as diesel has much more sulphur than gasoline.
Volatile organic compounds (VOCs) VOCs are a carbon-containing compound. In vehicle exhaust, VOCs come from unburned or partially-burned fuel. Additional VOC emissions come from evaporation of fuel (particularly during refuelling). Gasoline engines emit a higher proportion of VOCs than diesel engines, due to the greater volatility of the fuel.