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AirCare was implemented in 1992 to improve the quality of the air in the Lower Fraser Valley. Since 1992, air quality has improved, but many factors have played a role in this improvement.
The effect of AirCare is equal to the difference in the air quality we enjoy today versus what the air quality would have been like if there had never been an AirCare program. Of course, it can only be estimated what our air quality would be like if there had never been an AirCare program (more on that later).
However, the simplest way of looking at how AirCare works is recognizing that defective motor vehicles pollute more than they normally would, so identifying and repairing those defects results in lower emissions.
How Much Dirtier Are Failing Vehicles?
Vehicles that fail an AirCare tailpipe test have higher emissions output than normal vehicles of the same age and type. When failing vehicles are repaired correctly, their emissions are significantly lower than they would be if allowed to continue to operate without repair.
Exactly how much more a defective vehicle pollutes depends on a number of factors including the emission control technology built into the vehicle and what the specific defect is. In many cases, driving a defective vehicle is the equivalent of driving several normally operating vehicles.
The chart above shows the average emissions by inspection result. On average, failing vehicles have approximately 2.5 times the emissions of a passing vehicle.
Therefore, if 10% of the vehicles are failing inspection, the fleet total emissions are increased by 15% (.9x + .1(2.5x) = 1.15x). Repairing these vehicles and restoring their emissions output to normal levels can therefore produce a 15% reduction in emissions.
It's Both Technology and Maintenance
How does one separate the effect of AirCare from the other effects? This requires the use of a computer model called MOBILE 6.2C. This model incorporates assumptions about the reductions that would occur by having an emissions inspection and maintenance program like AirCare. By turning off the assumption of a program, the model will calculate how emissions would progress based on fleet turnover alone.
Based on MOBILE 6.2C as run by the GVRD, the 2004 inventory would have been lower by 42% as a result of fleet turnover alone. However, the difference between the MOBILE 6.2C prediction and the “State of the Fleet” observed inventory implies an additional reduction of 29% that can be attributed to AirCare.
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