Smog and You

   Lucie Lafrance
   Environment Canada
   February 2000


hat is Smog?
Originally, the term "smog" referred to a mixture of smoke and fog in the air. Today, "smog" describes a noxious mixture of air pollutants—including gases and fine particles—that can often be seen as a brownish-yellow or greyish-white haze.

In Canada smog is a concern in most major urban centres but, because it travels with the wind, it can affect sparsely populated areas as well. Particularly vulnerable to smog are the elderly, those with existing heart or lung disease and small children. Even healthy adults can be adversely affected by high levels of smog.

(photo: Environment Canada )


The two key components of smog are airborne particles and ground-level ozone:

Airborne Particles: These are minute solid or liquid particles that are small enough to remain suspended in the air. Particles give smog its color, which may be brown, dark gray or white, depending on the type of particles. Small particles, less than 10 micro- metres, have a significant effect on human health, particularly for those who already suffer from heart or lung disease. Of particular concern are the fine particles, less than 2.5 micrometres that can penetrate deep within the lungs. Fine particles may remain suspended in the air for days or even weeks and may be transported long distances. The major environmental problem of airborne particles, besides its health impact on humans, is reduced visibility.

Ground-Level Ozone: Unlike the ozone that forms naturally in the stratosphere, ground-level ozone does not provide any significant protection from the sun's harmful UV rays, nor does it find its way to the upper atmosphere. Ozone is a colorless and highly irritating gas that forms naturally when sunlight "cooks" the soup of air pollutants often found over urban areas on hot summer days. The precursor air pollutants, nitrogen oxides (NOx) and volatile organic compounds (VOC), react with each other to produce ground-level ozone.

Most Canadians in urban areas live where ground-level ozone may reach unacceptable levels during the summer months. Periods of high ozone can last several days and frequently occur when a stagnant air mass traps pollutants over a region. Recent studies have shown that every major Canadian urban centre has levels of ground-level ozone high enough to pose a health risk.

Not only is ozone a problem for humans, it is also known to damage vegetation and cause the deterioration of some natural and synthetic materials, including paints and dyes. Ozone is also a powerful greenhouse gas, which contributes to climate change.

Where does it come from?

On a national basis, 59 percent of (NOx) emissions and 27 percent of VOC emissions come from the transportation sector. Other major sources of the pollutants include the power generating sector and other industrial activities. This means that individual Canadians are responsible for generating the pollutants and, in turn, by making lifestyle choices, can make a big contribution cleaning up the problem.

(photo: Environment Canada)

What you can do...

Many of the choices that we make every day have a direct impact on the amount of pollution that goes into our air - from the way we get to work in the morning to the way we heat and cool our homes. Since burning fuel is a primary contributor to smog formation, reducing energy use and making wise consumer decisions are important steps toward cleaner air. Learn as much as possible about alternative energy sources, and discuss your concerns about smog with other people-including your children. Join a community group working for cleaner air. Following are some simple tips to pass along.

Go public. Use public transportation or car-pool instead of using your car; after all, one bus-load of passengers saves nine tonnes of air pollution each year. If smog levels are not too high, try walking or cycling.

Be fuel efficient. Make fuel efficiency a prime factor in your choice of a new car. Pass up options, such as air conditioning, that burn more gas; buy a smaller vehicle to reduce pollution and travel costs; and consider alternative fuels such as propane, natural gas and ethanol.

Stay tuned. Keeping your car engine tuned and your tires properly inflated increases fuel efficiency.

Drive smart. Transport Canada estimates that differences in driving style can lead to a 20 percent variation in fuel consumption. Driving at moderate speeds and avoiding quick starts and stops uses less fuel.

Turn it off. Idling your car engine for even one minute uses more fuel than turning it off and re-starting it. Most cars and trucks require only 15 to 30 seconds of idling before being driven, even in winter.

Say good-bye to gas. Swap gasoline-powered vehicles and machinery, such as motorboats, motorbikes and gas lawnmowers, for human-powered versions like canoes and sailboats, bicycles, and electric or push lawnmowers.