Smog is a complex mixture of many air pollutants, mainly ground-level ozone (O3) and fine particulate matter, both of which are formed in the air under the influence of heat and sunlight. Ground-level ozone is invisible. Fine particulate matter consisting of tiny particles suspended in the air as either liquid or solid, may give the air a hazy appearance. Nitrogen dioxide gas gives the air a dirty, brown color.

Polluted air covers large areas over both urban and rural areas. One of the worst smog areas in Canada is southwestern Ontario along the north shore of Lake Erie and the Lake Huron shoreline up to and including the Bruce Peninsula. Studies suggest the high smog in this area is caused mainly by pollutants carried by south-westerly winds from the Ohio Valley, Illinois and Michigan. Smog often blankets southern Ontario from Windsor to Quebec City along the Lake Huron shoreline (known as the Windsor-Quebec corridor) and sometimes goes as far north as Sudbury and North Bay in the hot still summer months (see figure). Other bad smog areas in Canada are B.C.'s lower Fraser Valley which collects its pollutants from the Vancouver area, and the southern maritimes when south-westerly winds blow up from the New England area.

Half of Ontario's smog originates from American coal-fired generating stations and industry in the United States , but the rest comes from automobiles, and from Ontario's five coal-fired stations near Hamilton (2), Sarnia, Thunder Bay and Atikokan. In 1997 Ontario Hydro had to shut down seven of its 19 nuclear reactors for refitting, and to make up for the loss of power, the utility increased the output of its coal-fired stations. Since then, smog emissions from these plants have increased about 80%. Coal-fired plants create ozone, nitrogen oxides, sulphur dioxide, carbon dioxide and toxic particulates. The smog from these plants is also laced with mercury.

The worst air polluter in Ontario is Co-Steel Lasco in Whitby. The worst polluter in the Toronto area is Ontario Power Generation Inc. (OPGI). Ontario Hydro was recently dismantled and split into three main entities, one of which is OPGI, which supplies 85% of Ontario's electricity. Ontario's nuclear reactors produce a steady stream of nuclear wastes. Tritium from the Pickering Nuclear Generator ends up in our air and Lake Ontario. Tritium has been linked to Down's syndrome among children in Pickering as documented by a 1991 Atomic Energy Control Board study. In the vicinity of the nuclear plants, strontium 90 is showing up in children's teeth and bones, and according to Dr. Jay Gould, people who live near reactors are far more likely to develop cancer (see Breast Cancer Conference article).

Although Ontario is rated as the third largest producer of pollutants (air, water and toxic waste) in North America (behind Texas and Louisiana), the Ministry of the Environment's budget has been cut 45% since Mike Harris was elected in 1995; staff levels have dropped 30% and there are insufficient inspectors to charge companies with infractions. And experts say that the summer smog in Ontario is becoming worse, not better.

People in the US can tune in to the smog weather maps, but the Canadian government is reluctant to advertise bad air quality, and is not adequately warning us of all poor air quality days. Although it is not well advertised in the media, the Ministry of the Environment in Ontario provides a daily report on the Air Quality Index (AQI) on a prerecorded phone message as well as on their website (see below). From 1 to 15 (AQI) is considered very good and from 15 to 30 is considered good air quality, but air quality index guidelines are presently being re-evaluated and the upper toxicity limits will probably be lowered. At present AQI levels apply mainly to ozone levels, but particulate levels will be soon added as a separate index.

Ozone levels are usually worse in the late afternoon and evening and return to better levels during the night and the early morning; fine particulates remain high throughout the day and tend to peak during hours of heavy traffic, so keep yourselves informed of heavy smog days and time your outdoor exercise accordingly.

References: Ministry of the Environment, Ontario.

Contact the Ministry of the Environment, Air Quality Index Report at 416-246-0411 or 1-800-387-7768 for a daily recorded message giving air quality indexes for bad smog areas in Ontario.
Or try their website at www.ene.gov.on.ca and go to the Air Quality Index section.
Smog information is also available at the Ontario Medical Association website at www.oma.org