Ontario's Drive Clean

Ontario's Drive Clean is an automobile emissions control program introduced by the Government of Ontario and came into effect April 1999. The program was initially intended to weed out vehicles producing unrestrained amounts of particulate emissions contributing to smog and increasing pollution. It applies only to vehicles registered in southern parts of Ontario from Windsor to Ottawa due to the volume of vehicles in that part of the province. It is administered by privately owned facilities (such as Canadian Tire and vehicle dealerships) that have been accredited by Ontario's Ministry of the Environment and Climate Change (MOECC) and the Ministry of Transportation (MTO).

At its inception, the program required light duty vehicles under 4,500 kg (cars, SUV, light trucks) that were over three years old to have an emissions test completed every two years (vehicles manufactured on even years are tested on odd years and vehicles manufactured on even years are tested on odd years) before the vehicle's owner or lessor can renew their licence plate. Vehicles that were manufactured up to and including 1987 are exempt as new vehicle emissions standards were coming into effect beginning in 1988. The minimum age for testing has been increased twice since the beginning of the program. As of 2011, vehicles that are over seven years old require emissions testing.

Heavy duty trucks and buses are also covered by Drive Clean program. They are tested annually once the vehicle is more than one year old, with no age limit to testing; A 1975 diesel powered truck or bus would still be tested so long as it was still registered. All vehicles on Ontario roads are further monitored by a 'smog patrol' team for MOECC and can be stopped at random and roadside tested. The Smog Patrol team drive vehicles that are equipped with mobile testing equipment to perform roadside tests. The Smog Patrol can also perform a visual inspection to ensure all emissions control equipment is in place and functioning as originally built (tampering with or removing this equipment is an offence separate from Drive Clean but under the same Regulation). Some registrants circumvent an emissions test by registering their vehicles to addresses outside the Drive Clean testing areas. Circumventing an emissions test in this way is an offence and could result in a ticket or summons and could also result in licence plates being seized.

...
Wikipedia