Three Pilot Projects
Canada has improved air quality forecasting and put in place a number of national actions to reduce emissions of particulate matter and ozone. The three pilot projects will explore how specific air quality tools can be used in both countries to reduce smog in areas of concern.
- The Georgia Basin/Puget Sound International Airshed Strategy for British Columbia and Washington State strives to identify ways to cut air emissions and address cross-border pollution.
- The Great Lakes Basin Airshed Management Framework in Michigan and southern Ontario explores the development of a coordinated airshed management approach.
- A study will examine the feasibility of emissions trading for nitrogen oxides and sulphur dioxide, the main contributors to smog, fine particles and acid rain.
The two countries committed to these pilot projects, fulfilling a pledge made in January 2003, under the Border Air Quality Strategy. The Strategy is designed to build on the success of the 1991 Canada-United States Air Quality Agreement, which established a framework for collaboration on science and emission reductions in both countries. For more information on these initiatives, please visit the Canada-United States Border Air Quality Strategy.
What is Smog?
|
North American Ground-Level Ozone Map at 50m (PPB) - July 2003. Click to enlarge.
|
Most Canadians are familiar with the brownish, yellow or grey haze that can hover over the city during hot summer months. It is called smog, a noxious mixture of airborne substances. While large cities are often burdened with smog conditions, rural communities are also affected as winds carry smog across the countryside.
The Science of Summer Smog
Summer smog has two main components: ground-level ozone and particulate matter (PM). Ozone is a colourless gas, while PM gives smog its milky or grayish colouring. Smog is actually an air pollution soup with many other components, one of which, nitrogen dioxide gas, contributes a yellow or brownish colour to the mix.
- Ground-level ozone: forms near the earth's surface, when other pollutants, nitrogen oxides (NOx) and volatile organic compounds (VOCs) react under bright sunlight. Since it is formed by reactions between emitted or primary pollutants, it is termed a secondary pollutant. Ground-level ozone should not be confused with stratospheric ozone, which provides protection from harmful UV rays. Although it is the same substance, stratospheric ozone forms differently and in the upper atmosphere, and does not contribute to ground-level smog episodes.
- Particulate Matter: is composed of minute solid particles or droplets of liquid that are small enough to remain suspended in the air. When inhaled, it can penetrate deeply into the lungs. This is both a primary and a secondary pollutant, since such fine particles are emitted directly and can also form through chemical reactions in the air.
Under certain conditions summer smog can reach harmful levels, as measured by high ground-level ozone or PM concentrations. To start, there must be primary pollution emissions, either locally or upwind. Then, strong sunlight is necessary to drive the chemical reactions to form ozone and PM. Finally, there must be a stagnant air mass, so that emitted pollutants cannot disperse, but accumulate and move slowly downwind.
Weather, climate and land surfaces play a major role in smog conditions. Heavy rain can clear away smoggy conditions. Also, geography is another factor, as flat regions allow the wind to push smog out of the area, whereas mountainous terrain can trap smog in the valleys. When smog levels are expected to be high, smog alerts are issued.
Human activities are major contributors to increased smog levels.
- About 95 per cent of NOx from human activity comes from burning coal, gas and oil in motor vehicles, homes, industries and power plants.
- VOCs mainly come from gasoline combustion and from the evaporation of liquid fuels and solvents such as nail polish remover, barbecue starters, paints and cleaners.
- Factories, thermal power plants, vehicle exhaust, wood burning and construction produce primary PM emissions and pollutants which react to form secondary PM.
|
|
