Peace and Environment News* June 1995
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Peace and Environment News * June 1995 |
by Heather Burke
According to the media and tourism brochures, Ottawa is a clean city. But just how clean is Ottawa really? In the accompanying chart, we have compared Ottawa to Toronto and Regina on common air pollutants to see how we measure up. We chose Toronto as the stereotypical big bad city. But is our air quality really much better than Toronto's? You will note that there is very little difference between Ottawa and Toronto except for ozone levels. Overall, Regina has one of the best air quality levels of the major Canadian cities. It shows us what we are capable of achieving.
Acceptable levels of different pollutants have been set to form the National Ambient Air Quality Objectives (NAAQO). These guidelines take in to account only immediate effects, such as respiratory problems in humans and damage to plant life. The guidelines do not take into consideration illnesses such as cancers which may occur as a result of long-term exposure.
There are three levels of acceptance before air quality becomes entirely intolerable. Desirable generally means that there are no known immediate effects on plants or animals. Acceptable means that adequate protection is provided for humans, animals, vegetation, soil, water, materials and visibility. When a pollutant reaches the maximum tolerable level of concentration, immediate action is required to protect the health of the general population.
The pollutants we looked at are the ones that are measured at every monitoring station in Canada: sulphur dioxide, nitrogen dioxide, carbon monoxide, ground level ozone and total suspended particulate.
Sulphur dioxide causes damage to some species of vegetation, even within acceptable levels set by the (NAAQO). Tolerable levels cause sensitivity in patients with asthma and bronchitis, and higher levels may lead to breathing difficulties among hypersensitive individuals. Heavy industry, such as the smelting of non-ferrous metals, is the primary source of sulphur dioxide.
At levels defined as tolerable by the NAAQO, nitrogen dioxide causes increased rates of respiratory illness, odour and atmospheric discolouration. Higher levels lead to increased sensitivity in patients with asthma and bronchitis. Nitrogen dioxide is produced by combustion, the major source being cars and trucks.
Within the acceptable range, carbon monoxide in the air causes cardiovascular symptoms in smokers with heart disease. Changes in blood chemistry can also be observed. Within the tolerable range there are cardiovascular symptoms in non-smokers with heart disease, as well as some visual impairment. At higher levels there is physiological stress on persons with cardiovascular and respiratory disease and possible increased mortality. Cars and trucks produce 75 percent of carbon monoxide.
Although the ozone in the stratosphere protects us from the sun's UV rays, at ground level ozone causes injury to some species of vegetation, even at acceptable levels. Even at tolerable levels, ozone causes decreased performance in some athletes. Higher levels of ozone eventually cause impairment of the respiratory function. Ozone is created on hot, sunny days with a stagnant air mass from volatile organic compounds (VOCs) and nitrous oxide. The major source of both of these pollutants is gasoline-powered vehicles.
Total suspended particulate is a term that applies to a wide variety of solid or liquid particles that remain suspended in the air. This is the pollutant that is most commonly perceived as air pollution, as it causes reduced visibility, soiling of materials and irritation of the respiratory tract. Visibility reduction is noticeable at acceptable levels. At tolerable levels there is an increased frequency and severity of lower respiratory disease in children. At higher levels, patients with asthma and bronchitis are affected. Sources of this pollutant are varied: industrial emissions (mining and pulp and paper mills) and fuel combustion emissions, mainly from thermal power plants and gasoline-powered motor vehicles.
Information summarized from the October 1994 Environment Canada Report "National Urban Air Quality Trends 1981-1990".
| Maximum Desirable Level | Ottawa | Toronto | Regina | |
|---|---|---|---|---|
| Sulphur Dioxide (SO2) | 11 ppb annual average | 4.0 ppb | 4.9 ppb | 1.0 ppb |
| Nitrogen Dioxide (NO2) | 32 ppb annual average | 25 ppb | 26.1 ppb | 20.0 ppb |
| Carbon Monoxide (CO) | 8-hour is 5 ppm | 1.0 ppm | 1.3 ppm | 1.2 ppm |
| Ozone (O3) | 1-hour is <50 ppb desirable <82 ppb acceptable <153 tolerable |
78 ppb | 115 ppb | 60 ppb |
| Suspended Particulate | 60 µg/m3 annual average | 43 µg/m3 | 56 µg/m3 | 37 µg/m3 |
| ppb = parts per billion | ppm = parts per million | µg = microgram | ||
| 1986-1990 Average Levels of Air Pollutants in Three Cities. Information taken from the October 1994 Environment Canada Report "National Urban Air Quality Trends 1981-1990." | ||||
Converted July 7, 2000 - Lg
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