Photochemical smog is a noxious mixture of gases formed in the lower atmosphere when sunlight acts upon certain pollutants such as industrial pollutants and exhaust from cars and trucks. The main component of smog is ground-level ozone. Where does SMOG come from? Ground-level ozone is produced by a reaction between nitrogen oxides (NOx) and volatile organic compounds (VOC) in the atmosphere. NOx is produced when fossil fuels such as gasoline, natural gas, heating oil and coal are burned, for instance, in transportation and electricity generation. VOC comes mainly from the evaporation of liquid fuels, solvents and organic chemicals and from gasoline burning. Because smog- forming reactions depend upon temperature and sunlight, smog problems are generally more acute on hot, sunny summer days.
Smog can be a powerful and irritating pollutant. Even short term exposure of only one or two hours can irritate our nose and throat, and cause respiratory problems such as coughing and painful deep breathing.
Exercising outdoors increases the likelihood of respiratory difficulties due to smog, since more air is inhaled during physical activities. In addition, ground-level ozone increases our susceptibility to other respiratory illnesses and may result in premature aging of the lungs.
The higher levels of ground-level ozone that contribute to smog often damage agricultural crops and vegetation. Current agricultural losses are estimated to be nearly $70 million in Ontario and $9 million in the Lower Fraser Valley of British Columbia. Furthermore, excessive ozone levels may also contribute to the decline of several Canadian forest areas.
While ozone is everywhere in the atmosphere, higher levels are concentrated in two main areas: the stratosphere, located between 15km and 40km above the Earth's surface, and at ground-level where we live and breathe. Ozone occurs naturally in both of these areas, but at certain times of the year the natural balance is disturbed by too much ozone at ground level and too little in the stratosphere.
Stratospheric ozone plays an important role in the atmosphere. It forms a protective layer around the Earth as it absorbs the intense ultra-violet radiation from the sun and prevents most of it from reaching the Earth's surface. The consequences of more intense radiation reaching the Earth are serious. Although some ultra-violet radiation is needed to sustain life and help plants grow, too much radiation increases risk of skin cancer and eye cataracts, and reduces yields of important agricultural crops such as wheat, rice, corn and soya beans. Therefore, it's important that we ensure levels of this beneficial stratospheric ozone don't continue to diminish.
Ground-level ozone occurs naturally, but only in very low concentrations. These concentrations increase when pollutants in the air react in the presence of sunlight under warm temperatures and result in harmful levels of ozone.
Controlling NOx and VOC is one of the best ways to limit ground-level ozone to acceptable levels.
Yes. In some areas of the country, smog is one of the most serious air quality problems we have. Our problems are not as severe as those in cities such as Los Angeles or Mexico City, but they warrant our immediate attention. The Canadian Ambient Air Quality Objective for ground-level ozone is 82 parts per billion. In several of Canada's major cities, summer ozone levels can exceed our air quality objective. For example, Windsor, Toronto, Montreal and Vancouver are cities where the ozone air quality objective is exceeded an average of 10 or more days in the summer.
When levels of smog reach harmful proportions, it is wise to change our outdoor activities in the following ways:
The frequency and severity of smog depends upon the size of a city, its population and vehicle density and the kind of industry it supports. Smog is not just a city problem; it flows into rural areas as well. Since ozone, NOx and VOC can be transported by air over long distances, the frequency and severity of smog in a particular area can be affected by smog levels in areas several hundred kilometres away.
Climate and topography also affect smog levels. Although rain can clean the air of the pollutants that cause smog, this may result in acidic rain water. Wind, too, can blow smog away, but if cities are surrounded by hills or mountains, air flow patterns are reduced, and smog levels increase.
In November 1990, the Canadian Council of Ministers of the Environment (CCME) adopted a Management Plan designed to reduce smog-producing emissions across the country. The first phase of the Management Plan, now in implementation, includes the development of regulations, guidelines and other initiatives to lower NOx and VOC.
A number of control initiatives are currently being implemented. These include car inspection and maintenance programs such as "AirCare" in British Columbia and the recovery of gasoline vapours at Vancouver- and Toronto-area service stations. In addition, new nationwide automobile emission standards, and control programs for the control of commercial emission sources in the Montreal area, have been set. These controls involve paint applications, printing and dry cleaning.
The Greater Vancouver Regional District has also approved an Air Quality by-law which includes new measures designed to limit both point and mobile emission sources.
As part of the CCME Management Plan, a public awareness and education program is being implemented at the national level. This fact sheet is one of the products of this program.
Several regional public education projects are underway across the country to help Canadians learn to reduce smog.
In the Lower Mainland of B.C., an inter-agency network called GO GREEN is in the third year of an awareness and education campaign aimed at reducing total motor vehicle emissions in the region. The GO GREEN program promotes transportation alternatives to solo driving and links the initiatives of its municipal, provincial and federal partners for maximum effects.
GO GREEN's lead partner is the public transit agency BC Transit. In November 1991, BC Transit introduced the first training program in Canada focusing on trip reduction techniques for commuters. This training pioneers the application of Transportation Demand Management principles, which extend well beyond alternative transportation, to provide a framework for policy development and regulation. The regional municipality of Ottawa-Carleton in Ontario has introduced the Transportation Environment Action Plan, a public education program to teach people about alternative transportation techniques. The program has developed innovative ways to show how commuting to work can be made easy through public transit, walking, cycling and ridesharing.
In Toronto, the Healthy City Office is developing a public education program to promote the use of public transit, make cycling to work safer, easier and more convenient, and provide partners for employees who want to rideshare.
The City of Calgary is initiating the world's first voluntary automobile emissions testing program. The program, called "SMOG FREE", is an acronym for "Save Money On Gas ... From Reduced Exhaust Emissions." Under the program, Calgary residents will be able to get their vehicle emissions measured at local service outlets. Sponsors will offer coupons called "SMOG FREE BUCKS" for a ten dollar reduction on service costs to improve or repair exhaust systems.
Here are a few ways that people can limit the production of smog:
Since smog is primarily a result of fuel burning, reducing energy use and making wise buying decisions all contribute to cleaner air.
The State of Environment (SOE) reporting group at Environment Canada is publishing an in-depth background article on smog, its origin, its extent and ways to reduce it. The Environmental Health Directorate at Health and Welfare Canada has also produced extensive information on the effects of smog on our health.
Visit the Environment Canada National Site and search under "smog program".
This document was produced by the Canadian Council of Ministers of the Environment (CCME) and is available in hard copy from CCME Documents, fax 204-945-7172 or e-mail: email@example.com.
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