What is smog?

(Jun 6, 2007) In the last 20 years clear skies have become harder to find as most major cities have a permanent blanket of smog overhead. But, there are steps each of us can take that will make a difference.

What is smog exactly?
The term “smog” was first used more than 30 years ago to describe a mixture of smoke and fog that had settled over Los Angeles. At first smog meant only ground-level ozone but over the last decade that definition has changed to include PM (particulate matter), Ozone, SO2 (sulphur dioxide), NOx, (nitrogen oxide), VOC (volatile organic compounds) and NH3 (gaseous ammonia). That’s quite a mixture for us to breathe and as a result asthma rates in North America are four times higher than 20 years ago. Worldwide, between 30% and 40% of asthma cases and 25% of all respiratory diseases may be linked to air pollution.

Why is smog so dangerous?
Smog is divided into two categories of primary or secondary components. Secondary components are created when primary pollutants react together. PM belongs to both classes. Primary PM is emitted at the source, for example, from the smokestack of an electrical power plant. Secondary PM forms when SO2, NOx and NH3 mix together.

Ozone is considered a secondary pollutant because it is produced from a combination of nitrogen oxides (NOx) and volatile organic compounds (VOCs). While SO2, NOx and VOCs do occur in nature, human activity is responsible for the bulk of these pollutants.

About 95 per cent of NOx is created from burning coal, gasoline and oil in vehicles, homes, industries and power plants. SO2 comes from burning coal and other fossil fuels. VOCs comes mainly from the production of oil, gasoline and the consumer byproducts created from both. Residential wood combustion and the evaporation of liquid fuels and solvents also put VOCs into the air.

All of these components have been linked to asthma, heart attacks and strokes, lung cancer, and premature death.

Take part
There is little debate amongst scientists and researchers that smog could be greatly reduced if we cut down the burning of fossil fuels. What can you do to help improve the air quality in your community? Here are just a few suggestions offered by Clean Air Day and Environment Canada:

walk, bike or use public transportation instead of driving

use electric or manual lawn equipment rather than gas-powered

don’t let your car idle for more than 30 seconds

keep your vehicle in good working condition

drive a hybrid car

purchase Energy Star appliances

compost and reduce your garbage

Is your city here?
The top five international cities with the worst air pollution are:
1. Beijing, China
2. Mexico City, Mexico
3. Sao Paulo, Brazil
4. Cairo, Egypt
5. New Delhi, India

The top five U.S. cities with the worst air pollution are:
1. Los Angeles-Long Beach-Riverside, California
2. Pittsburgh-New Castle, Pennsylvania
3. Fresno-Madera, California
4. Bakersfield, California
5. Logan, Utah

The top five Canadian cities with the worst air pollution are:
1. Toronto and the GTA region
2. Montreal
3. Vancouver
4. Quebec City
5. Calgary



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