Many benefits will be realized when the Ontario Drive Clean Programs is fully implemented.  This program will cut smog-causing pollutants from vehicle sources by up to 22 per cent.
 
Ontario's Drive Clean program is concerned with helping us make smart choices about the way we maintain and drive our vehicles. Driving clean can save you up to 10 per cent in annual fuel consumption and prolong the life of your vehicle. But more importantly, you will be doing the right thing for the air we breathe.

The Drive Clean program, which requires vehicle emissions testing, is one of a number of measures the province is taking to combat smog, a major domestic source is vehicle emissions.  Smog causes health problems, especially for children, the elderly and people with respiratory and heart conditions.

What is SMOG??
The word smog was coined to describe the deadly combination of smoke and fog during a
particularly severe episode in London, England. The smog we experience here in Ontario  is different, being composed largely of ozone and fine particles. Much of the pollution that contributes to the formation of smog in southern Ontario comes from the United States. Ozone is created when nitrogen oxides and volatile organic compounds (VOCs) combine in the presence of sunlight. Plenty of sunlight is needed to create smog, which is why we get more of it in summer than in winter.

Fine particles, the other major component of smog, are emitted directly into the air from many sources. They are also formed in the atmosphere from the chemical reaction of gaseous pollutants. Inhalable particles ( PM10) are less than 10 microns in diameter. Respirable particles (PM2.5) are less than 2.5 microns small enough to get deep into our respiratory systems.