Emissions Info - How AirCare Works
It's Simpler Than You Think
AirCare was implemented in 1992 as one of a number of control measures aimed at improving air quality in the Lower Fraser Valley. Since 1992, air quality has generally improved (external link) despite increases in population and the number of vehicles on the road, but many factors have played a role in this improvement.
The benefit of AirCare can be described as the difference in the air quality we enjoy today versus what it would have been if there had never been a 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 explaining how AirCare works is that vehicles with worn-out or broken emission control components pollute more than they normally would, so identifying these vehicles and requiring that they be repaired results in lower emissions and improved air quality.
How Much Dirtier Are Failing Vehicles?
Vehicles that fail an AirCare test have considerably 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 failing vehicle pollutes depends on a number of factors, such as the emission control technology built into the vehicle, and the nature of the defect. 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. The chart is based on AirCare data for vehicles randomly selected from the passing population, and from pre and post-repair results of vehicles that fail. The chart indicates that, on average, failing vehicles have approximately double the emissions of a passing vehicle. Identifying and repairing these vehicles and restoring their emissions output to normal levels can produce a significant reduction in emissions. The difference between the red and blue bars visually represents the reduction. It can be seen that post-repair emissions match closely the results of passing vehicles, suggesting that complete repairs are being done.
Direct and Indirect Benefits
In the latest report of AirCare program benefits, AirCare - Results and Observations 2009 and 2010, the emission reductions attributed to repairs performed were as shown in the table below:
| HC Reduction | CO Reduction | NOx Reduction | |
|---|---|---|---|
| Source: AirCare - Results and Observations 2009 and 2010 | |||
| 2009 | 10% (488 tonnes) | 9% (7,334 tonnes) | 4% (299 tonnes) |
| 2010 | 9% (391 tonnes) | 8% (5,765 tonnes) | 4% (278 tonnes) |
The direct effect of AirCare repairs was estimated by calculating a baseline inventory in which all vehicles are considered to be emitting at the levels suggested by their initial test results (ie. all failing vehicles at their pre-repair levels). For the vehicles that return for re-inspection, we can substitute the re-inspection emission levels and calculate a new inventory. The difference between these two scenarios and the percentage reduction relative to the baseline are shown in the above table for 2009 and 2010.
In addition to the short-term reductions, it could be assumed that many of the vehicles that have failed AirCare since its inception would not have otherwise been repaired and might have continued to pollute excessively or even worsen over the years. Testing the vehicle fleet periodically and repairing the ones with the highest emissions creates a cumulative benefit that increases over time and multiplies the program benefits. AirCare's analysis has shown that most repairs tend to last two years or more, therefore, some portion of the benefit from the preceding year can be added to the benefits of any case year.
Another important factor is that some of the vehicles that fail AirCare tests are removed from use [external link] sooner than they normally would and therefore stop contributing to the region's total emissions inventory. The potential emission reductions resulting from this effect are about 50% of the effect of repairs to failing vehicles. This is calculated by assuming that the vehicles would have continued to operate for the remainder of the year at failing emission levels if not for the intervention of the program.
AirCare IM240 mass emission tests can be used to calculate an annual emissions output per vehicle, based on the AirCare test result and the estimated annual distance driven. Using vehicle registration data from ICBC (external link), it is possible to assign appropriate emission factors to each vehicle in the fleet along with a suitable estimate of annual kilometres driven. By aggregating the annual emissions output of each vehicle, an emissions inventory can be calculated.
Comparing the IM240 emissions inventories corresponding to the fleet composition as of January 1st of any given calendar year and assuming that vehicle emissions performance is represented by its initial AirCare inspection result, a “State of the Fleet” value can be derived for each year. This method accounts for the natural renewal of the fleet as well as any effect of AirCare since the cumulative effects of past AirCare testing are reflected in the “as-tested” emissions.
The calculation of successive IM240 inventory values reflects the rate at which vehicle emissions have been declining as a result of all factors. Note that IM240 emission factors apply only to the type of vehicle operation represented by the test cycle. Adjustments must be applied to account for different ambient conditions and driving cycles. Making the necessary corrections, AirCare staff have calculated that the emissions from the light-duty vehicle fleet on July 1, 2010 were 87% lower than they would have been in 1992.
How Does the Total Amount of Emissions Produced by Vehicles Today Compare to the Amount in 1992 Before AirCare Started?
The short answer is a lot lower. Since 1992, the active vehicle fleet has been substantially replaced with newer technology vehicles that were designed to meet increasingly more stringent emission standards. A major emission control technology change occurred starting with the 1988 model year when Canada harmonized its new vehicle standards with those of the United States. Prior to that, Canadian vehicles were allowed to emit 3-7 times what a comparable U.S. vehicle could, depending on the pollutant.
In 1992, a high proportion of the vehicle fleet in the Lower Fraser Valley consisted of pre-1988 vehicles, including significant numbers of vehicles that didn't even have a catalytic converter. Fast-forward to 2010, and almost all of the pre-1988 vehicles have worn out, and have been replaced with newer technology vehicles. In fact, many of those “newer technology” vehicles are now old and worn-out (see Figure 1). Typically, the vehicle fleet consists of vehicles from 0-14 years old, so in 1992 the fleet consisted of 1978-1992 model year vehicles, whereas the 2010 fleet ranges back to 1996. Of course, there are still pre-1996 vehicles on the road, but their numbers are very small.
Based on the smog-forming emissions inventory published for the LFV (external link), the inventory has decreased from 320,000 tonnes in 1990 to 205,000 tonnes in 2005. The light-duty vehicle portion of the inventory in 1990 was 95,000 tonnes (30% of the total), and in 2005, it was 34,000 tonnes (17% of the total).
Since the program began in 1992, AirCare has tested 2,573,405 vehicles of which 36% or 931,084 vehicles failed at least once. Approximately 98% of these vehicles were either repaired or removed from use. Repairs to failing vehicles and the replacement of older vehicles with newer ones having more effective and durable emission control systems have dramatically reduced the annual amount of emissions attributable to light-duty vehicles.
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 [external link]. This model incorporates assumptions about the reductions that would occur by having an emissions inspection and maintenance [external link] 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 Metro Vancouver [external link] (formerly GVRD), the 2009 inventory would have been lower by 50% 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 33% that can be attributed to AirCare.
Read more about program benefits.
