Parameters

Sulphur dioxide is generated both naturally and anthropogenically (man-made), including the processing and combustion of fossil fuels containing sulphur. It is a colourless gas with a pungent odour (similar to a lit match), and can be detected by taste and odour at concentrations as low as 300 ppb. Sulphur dioxide reacts in the atmosphere to form sulphuric acid and acidic aerosols, which contribute to acid rain (accounts for about 70% of the total acid rain generate). Sulphur dioxide combines with other atmospheric gases to produce fine particles, which may reduce visibility. Brief exposure to high concentrations of sulphur dioxide and its products can produce human health effects, irritating the upper respiratory tract and aggravating existing cardiac and respiratory disease. Long-term exposure may increase the risk of developing chronic respiratory disease.

Ground-level ozone is formed by photochemical reactions in the atmosphere. It mainly comes from vehicle and industrial emissions in urban centres. It can be a major component of smog during the summer, especially during hot sunny weather, and is generally low in the winter. Ozone can be transported long distances and can be responsible for large regional air pollution episodes.

Oxides of nitrogen, mostly in the form of nitrogen oxide (NO) and nitrogen dioxide (NO2), are produced by the high temperature combustion of fossil fuels. Nitrogen oxide is the predominant species emitted by combustion sources, but it is rapidly changed to nitrogen dioxide in the atmosphere. Nitrogen dioxide is a reddish-brown gas with a pungent irritating odour. It has been linked to respiratory disease and contributes to acid rain. It plays a major role in atmospheric photochemical reactions and ground level ozone formation and destruction.Motor vehicles account for over 50% of the total NO2 generated, however, any combustion source will emit nitrogen dioxide (e.g. power plants, furnaces, space heaters) Some natural sources include volcanoes, lightning, biological decay, oceans.

Total reduced sulphur includes hydrogen sulphide, mercaptans, dimethyl sulphide, dimethyl disulphide and other sulphur compounds. Sulphur dioxide is not included in the determination of total reduced sulphur. Sources include fugitive emissions from petroleum refineries, tank farms for unrefined petroleum products, natural gas plants, petrochemical plants, oil sands facilities, sewage treatment facilities, pulp and paper operations that use the kraft pulp process and animal feed lots.

Carbon monoxide is a colourless, odourless gas emitted into the atmosphere primarily from incomplete combustion of carbon-based fuels such as gasoline, oil and wood. Natural and human sources of carbon monoxide include burning of vegetation such as forest fires and wildfires, and emissions from vehicles.

Hydrocarbons are divided into two broad categories, “non-reactive” and “reactive” hydrocarbons. The major non-reactive hydrocarbon is the atmosphere is methane, which is a naturally occurring colorless, odourless gas recognized as a major contributor to the greenhouse effect. The reactive hydrocarbons consist of many volatile organic compounds, some of which react with oxides of nitrogen in the atmosphere to form ozone. They generally occur at much lower concentrations than methane. Total hydrocarbons (THC) include both reactive and non-reactive hydrocarbons. Large amounts of methane are produced naturally through the decay of vegetation but human activity is contributing to a worldwide increase in methane concentrations of about 1% per year. Trees and plants are major natural emitters of reactive hydrocarbons with other significant sources include motor vehicles, petroleum refineries, petrochemical plants, chemical solvents, vegetation decay and combustion from burning coal, gas and wood.

Ambient particulate matter consists of a mixture of particles of varying size and chemical composition. Particles that are less than 10 micrometers in diameter (PM10) can be inhaled. The fraction of particles, which are less than 2.5 micrometers in diameter (PM2.5) can be trapped in the airways and lungs and is believed to cause adverse health effects. Fine particles (PM2.5) also reduce visibility and can contribute to acidification of soils.

PM10 size particles include windblown soil, road dust and industrial activities. PM2.5 size particles are formed from gases released to the atmosphere by combustion processes such as from motor vehicles, power plants, gas processing plants, compressor stations, household heating and forest fires. Pollen and bacteria also account for particulate matter.

Meteorological parameters measured are:

wind speed and direction
temperature
precipitation
relative humidity

WCAS monitors 8 air quality parameters in our airshed region.

Quick Links

Get Social

View Live Air Data

Newsletter Sign-Up