Six Contaminants Are Monitored Across Canada
Combustion of fuels and smelting of metal ores are major sources of sulphur dioxide. Sulphur dioxide undergoes chemical reactions in the air; these reactions produce sulphuric acid which dissolves in rain making it acidic. Sulphate salts also form; they contribute to the formation of respirable particulate matter (PM2.5 ) in the air.
Ozone is a major component of smog which is an air quality problem in Canada. During the summer months, more than one-half of all Canadians are exposed to ozone concentrations which are known to have adverse health effects.
Combustion of fuels and cleaning of metals are major sources of nitrogen oxides (nitrogen monoxide, nitrogen dioxide). Nitrogen oxides undergo atmospheric reactions which produce ozone, a major component of smog. Nitrate salts are also formed which contribute to increased levels of respirable particles in the atmosphere; these too are smog components.
Volatile Organic Compounds (VOCs)
These compounds are emitted to the atmosphere from a variety of sources which include transportation, industrial and commercial facilities, hazardous waste storage and treatment facilities. VOCs vaporize readily and are thus capable of being transferred over long distances in the atmosphere; they warrant special attention because they undergo reactions in the atmosphere which produce ozone, a major component of smog.
Particulate Matter (PM)
Particulate Matter , a major component of smog, is a general term used for mixtures of solid particles and liquid droplets in the air. PM 2.5 (respirable particulate matter) represents particles that are less than 2.5 micrometres in diametre. These very small particles are a health concern because, when inhaled, they penetrate deeply into lungs. 1 micrometre=1/1,000,000 metre
Total Reduced Sulphur (TRS)
Hydrogen Sulphide is an example of a totally-reduced compound; it is readily recognized by its rotten-egg odour. Wastes from chemical plants, paper mills and tanneries may contain hydrogen sulphide. Such wastes are commonly incinerated. Incineration of these wastes produces sulphur dioxide which can be captured through the use of sulphur dioxide scrubbers.
Ethylene, though not extensively monitored across Canada, is monitored in Sarnia-Lambton. Large quantities of this compound are produced and stored locally. Ethylene is used in the production of polyethylene, and other plastics, polyesters, anesthetics, silicones, pharmaceuticals, cosmetics, paint removers and also to accelerate the ripening of fruits and vegetables. Ethylene is uniquely stored in salt caverns which are some 600 metres below ground level in the Sarnia area.