Air

Particulate matter

Particulate matter consists of solid or liquid particles that are released into the air and are small enough to be inhaled. These include dust, soot, chemicals and other bits of material. Particulate matter is produced by natural sources (such as dust, volcanoes and forest fires) and human activities (such as mining, wood stoves, vehicle transportation and the burning of fossil fuels).

Particulate matter varies in size: fine particulate is less than 2.5 micrometres in size (a micrometre is one-thousandth of a millimetre) and coarse particulate is less than 10 micrometres wide. These particles can travel thousands of kilometres from their sources.

Particulate matter can reduce visibility and contribute to asthma, bronchitis and other respiratory problems. It also combines with nitrogen oxides and other emissions to form smog. Fine particulate can penetrate deep into the lungs and poses a greater risk to human health than coarse particulate.

Canada uses the Index of Quality of Air, a national assessment process, to measure air quality across the country. The index shows that, while air quality has improved since the 1980s, the number of “fair” and “poor” days increased between 1995 and 1998. This was because of higher levels of airborne particulate matter and ground-level ozone.

The electricity industry’s share of Canada’s particulate emissions is about 13 per cent.

Industry addresses particulate emissions through emission control equipment. For example, huge air filters called electrostatic precipitators can remove 99 per cent of fly ash from coal-fueled power plant stacks before it is released into the atmosphere. Baghouses, large enclosures containing fabric filter bags, are also used to remove particulate emissions from plant stacks.