The air that we breathe

Canadians inhale a variety of gases and particles that come from motor vehicles, various industries, heating equipment and even the glue used in manufacturing their furniture. But they can at least take comfort in knowing that some air pollutants have been reduced.

The fact is that Canada has seen an appreciable decrease in the major air pollutants. For example, in 2000 the 2.5 million tonnes of sulphur dioxide released into the air represented a 45% reduction from 1980. The level of sulphur dioxide is expected to continue to fall as a result of the passage of The Sulphur in Gasoline Regulations in 1999. The regulations stipulate that low sulphur gasoline will be required throughout Canada beginning in 2005.

Each year, every one of Canada’s 15 million cars and light trucks discharge over 4 tonnes of pollutants into the air. In urban areas, vehicles produce up to three-quarters of the pollutants that combine to form ground-level ozone. When ground-level ozone combines with suspended particles, smog is formed. This type of air pollution is especially serious from May to September in the Québec–Windsor corridor, southwestern British Columbia, and parts of the Maritimes to which the winds push pollution from the northeastern United States.

Carried by winds, air pollutants can travel vast distances before rain brings them down to earth. Thus, the Arctic regions are contaminated by pesticides originating outside North America. A serious amount of cross-border pollution between Canada and the United States has been identified. It resulted in the 1991 Canada–U.S. Air Quality Agreement, which has set targets for reducing pollution on both sides of the border. In addition to this, the Ozone Annex was added to this agreement in late 2000; it focusses on reducing nitrogen oxides and volatile organic compounds, the major components of smog.

During their stay in the atmosphere, some products react chemically to form acids that are returned to earth by precipitation. In the 1980s, it was learned that acid rain was devastating lakes and forests in southeastern Canada. Despite the steps that Canada and the United States took at that time to remedy the situation, it appears that 56% of acidified lakes are no better off today, while 11% have actually become more acidic. Only a third have shown substantial improvement.

There is also increasing concern regarding air quality in dwellings and office buildings, where the majority of people spend most of their time. Fumes from a multitude of products—including paints, building materials, electronic equipment and household products—could pose a danger to human health, especially in newer, tightly sealed buildings.