AirCare ON-ROAD Program

What is the AirCare ON-ROAD Program (ACOR)?

ACOR is a mobile inspection program operated by the BC Ministry of Transportation. Teams of certified ACOR inspectors run roadside tests of heavy-duty diesel vehicles, looking for excessive smoke emissions.

ACOR protects public health and helps provide safe, clean air by enforcing British Columbia's diesel emission standards.

Particulate Matter In Our Air

The exhaust from diesel vehicles contains particulate matter, which damages our health and environment. Particulate matter is a major component of smog and is linked to asthma and respiratory and cardiovascular illnesses. Children and the elderly are especially susceptible to its effects. The US Environmental Protection Agency has classified diesel particulate matter as a probable cancer-causing substance.

Incomplete fuel combustion produces particulate matter. In diesel engines, the fuel is sprayed directly into the combustion chamber through an injector. If some of the tiny droplets of spray do not burn completely, particulate matter is formed and emitted in the vehicle's exhaust.

One indicator of excessive particulate matter is the opacity of the exhaust smoke — in other words, how much light is blocked by the smoke. Higher opacity readings are correlated with higher particulate matter emissions.

ACOR identifies trucks whose engines are emitting excessive smoke as a result of a component failure, lack of maintenance or deliberate tampering with the engine settings.

ACOR Test Measures Opacity

ACOR inspectors use the standard snap acceleration test to measure the opacity of diesel emissions. The test is accepted in North America as the standard test for identifying malfunctioning diesel engines. It is used in air quality programs in Ontario and the United States.

How Does ACOR Work?

ACOR inspectors identify vehicles for testing through a visual inspection. Vehicles with dark smoke are more likely to be tested, because dark smoke is a sign the vehicle may be operating outside allowable limits.

The ACOR test will determine if your vehicle meets these emissions standards:

Model Year of Engine
Maximum Allowable Opacity
1991 and newer



If your vehicle fails to meet these standards, you may be ordered to have your vehicle repaired and retested, and you may be ticketed for violation of diesel emission standards under the Motor Vehicle Act Regulations.

How do you know if your trucks meet ACOR standards?

The ACOR team takes requests from companies to visit their sites and inspect their trucks. Call the ACOR office at 1-888-775-8785 to make arrangements for a site visit.

Technologies such as diesel oxidation catalysts, particulate traps or filters can significantly reduce particulate emissions. Combined with new, clean, ultra-low sulfur diesel, particulate emissions can be reduced by more than 90%.

Repairs Make Sense

Minimizing smoke emissions helps our environment and enhances the image of the trucking industry. A well maintained diesel engine also leads to lower fuel and maintenance costs and a longer engine life.

Emission problems become more common as vehicles age, but all trucks and buses, new and old, need proper maintenance to ensure they are running as cleanly as they should.

Most truck owners and operators recognize that a smoking truck is a problem truck. High smoke levels can be caused by many problems, including:

  • Restricted air filter
  • Improper injection timing
  • Clogged, worn or mismatched fuel injectors
  • Faulty or maladjusted fuel injection pump
  • Defective or maladjusted puff limiter
  • Low air box pressure
  • Improperly adjusted valve lash or governor
  • Air manifold leaks
  • Malfunctioning turbocharger
  • Malfunctioning after cooler
  • Defective air fuel controller
  • Poor fuel quality
  • Improper driving gear
  • Defective computer controls (sensors, wiring, etc.)
  • Clogged exhaust after-treatment devices or spent catalyst

Idling Can Be Costly

An idling diesel engine uses up to four litres of fuel per hour. It also produces much higher emission levels than it would on the road using the same quantity of fuel under load.

Extended idling causes a build-up of carbon soot inside the engine, plugging up holes in the fuel injector. This accumulated soot is often blown out in a puff of smoke when the truck accelerates. Studies suggest that an engine idling for one hour has the same effect on engine-carbon build-up as two hours of driving.

Think carefully before letting your vehicle idle. You will be doing your vehicle and our health and environment a big favour if you turn off your vehicle whenever possible.

Need To Know More?

The AirCare ON-ROAD program is operated by the Ministry of Transportation.
For more information on ACOR, call:1-888-775-8785

To make arrangements for an ACOR team to visit your community to test heavy-duty diesel vehicles for excessive smoke emissions, call 1-888-775-8785

If you see a truck that is smoking excessively, call 1-888-775-8785

For more information on the health effects,
see the Provincial Health Officer’s Annual Report 2003 at phoannual2003.pdf