DEQ recently performed a comprehensive analysis of the pollutants associated with automobile use in the Portland and Medford areas, including the emission reductions achieved by the VIP. The agency's SIP-VIP Updates Project: Emission Inventory Demonstration for Air Toxics and Ozone Precursors report summarizes the results of this analysis.
Among the findings, on-road emissions of pollutants would increase 7 to 20% if the vehicle inspection program were not operating in Portland, and 5 to 8% if the program were not operating in Medford. It should be, noted, however, that these estimates are most conservative in that they assume emission reductions arise only from vehicles that fail an emission test—approximately 6% of vehicles tested. Oregon vehicle data demonstrates, however, that nearly 25% of all vehicles tested and that pass an emission test do so because of maintenance performed shortly prior to the test. Therefore, it is understood that the emission-reducing impacts of the VIP and similar programs is magnitudes greater than current estimates.
The VIP's reductions to toxic air contaminants is important considering the direct, positive impact to the health of Oregonians. Toxic air pollutants, all of which form as a result of incomplete combustion, underlie a variety of health issues such as:
- Cardiovascular disease (1,3-Butadiene)
- Increased cancer risk (1, 3-Butadiene, 15-PAH, Acetaldehyde and Benzene)
- Upper respiratory system irritation (Acrolein and Formaldehyde)
- Adverse developmental and reproductive effects (Benzene)
- Anemia (Benzen and Naphthalene)
For reasons including these, the DEQ Vehicle Inspection Program remains focused on the critically important reductions to on-road emissions.