The combustion in a perfect gasoline-powered engine would produce only water and nitrogen — harmless byproducts — and carbon dioxide. In reality, no such engine exists, and even the most sophisticated, perfectly tuned engine produces unburned hydrocarbons, carbon monoxide and nitrogen oxide.
Hydrocarbons and nitrogen oxides that successfully escape through the tailpipe of a car eventually join to create ozone, a gas that can be disastrously harmful to both plant and animal life when it forms at ground level. According to the U.S. Environmental Protection Agency (EPA), even infrequent exposure to low levels of ozone can aggravate asthma, reduce lung capacity and increase susceptibility to respiratory illnesses, while repeated exposure may cause permanent lung damage.
Ozone production is only one negative effect of vehicle pollution. Nitrogen oxide molecules that do not bond with hydrocarbons drift into the atmosphere and eventually return to earth as acid rain. Carbon monoxide impedes the transportation of oxygen to the brain, heart and other tissues, presenting substantial health risks to babies and to people with heart disease. Particulate matter — microscopic particles produced by incomplete combustion — irritate lung tissue, causing or aggravating respiratory problems. Gasoline and diesel engines even produce toxic air pollutants, such as benzene and formaldehyde, that have been linked to cancer, genetic mutation, birth defects and other serious illnesses.
Recognizing the dangers of air pollution, the federal government, through the Clean Air Act in 1970, empowered the EPA to reduce motor vehicle pollutants.
A 1990 amendment to the law mandated vehicle-emissions testing for areas that violate the agency's standards for ozone and carbon monoxide levels.
Since 14 Ohio counties surrounding the Cincinnati, Dayton-Springfield and Cleveland-Akron metropolitan areas violated these standards, Ohio lawmakers established a vehicle emissions testing program. Under the program, labeled E-Check, car owners generally may not register a vehicle that produces more than the permissible levels of tested pollutants. Failing vehicles must be repaired and re-tested.
Administrative problems plagued this program shortly after it kicked off in 1996. Car owners often encountered long lines and rude, poorly trained personnel. Claims of improperly performed testing procedures damaging cars were too common. Adding to these woes, several Ohio lawmakers believe E-Check should be scrapped.
"E-Check doesn't work. It doesn't get cars off the road, it doesn't reduce pollution," says State Rep. Bryan Williams, R-Akron. "It is an unfair, ineffective way to deal with the EPA standards that have been forced upon us."
Williams and fellow Republican Rep. Timothy Grendell, R-Chesterland, have introduced nearly identical bills that would terminate E-Check. Williams has also introduced legislation that would exempt from testing cars that are between three and five years old. E-Check legislation currently exempts cars less than three years old. But is E-Check, as Williams claims, ineffective?
A careful reading of the Ohio EPA's 1999 E-Check evaluation report seems to indicate the program is directly responsible for cutting vehicle emissions. Using data collected at testing sites, the agency's researchers calculated improvements in the emissions of each vehicle that initially failed by comparing its final, passing emissions, measured after the car had been repaired, with the initial, failing emissions.
Data from this portion of the analysis clearly shows E-Check is working. Repairs made to the initially failing vehicles cut hydrocarbon emissions on average by 38 percent, carbon monoxide by 42 percent and nitrogen oxide by 10.4 percent. Interestingly, significant improvements occurred in vehicles between three and five years old, those Williams seeks to exempt. Improvements due to E-Check-mandated repairs cut average hydrocarbon emissions by 58 percent, carbon monoxide by 65 percent and nitrogen oxide by 20 percent in these cars, which comprised 3.4 percent of all failing cars in 1998. The raw before-and-after data collected at E-Check testing sites shows the program reduces pollution by requiring tune-ups and repairs.
But the EPA researchers then attempt to extrapolate these individual improvements into the total amount of pollution E-Check has removed from Ohio's air. The results of this exercise suggest E-Check has removed 24.5 tons of hydrocarbons from the air each day, well under the predicted reductions of 73.4 tons per day. This comparison, however, is muddled by numerous data collection and statistical problems.
First, the target of 73.44 tons is, by all measures, overstated. Since an EPA computer modeling program known as MOBILE 5a first churned out this estimate, the agency has introduced a refined modeling program, MOBILE 6, that yields results 30 to 60 percent lower. MOBILE 5a, therefore, inflated the expected impact of emissions testing to which E-Check has been compared.
Second, the emissions tests that Envirotest actually performed were much less stringent than those on which the predictions were based. To serve customers more quickly, whenever long lines formed at testing stations, technicians substituted a quicker but less accurate emissions test for the comprehensive test. The two-point tampering checks also replaced the original, comprehensive five-point check, and gas-cap pressure tests and other inspections were scaled back to cut testing time.
Finally, EPA researchers encountered problems converting the parts per million measurements used by Envirotest for some tests into the tons per day reductions required by the study. Failing to find a valid method of converting these measurements, the researchers used results from the overstated MOBILE 5a prediction to estimate those portions of the emissions test measured in parts per million. Amazingly, the researchers did this even though they admit in the report that no known correlation exists between the MOBILE 5a results and gaps they are attempting to fill.
Because of such data and statistical problems, none of the nearly 30 states with emissions testing programs attempt to translate individual vehicle emission reductions into an overall statement of their program's impact on air quality.
Another such E-Check evaluation is due from the Ohio EPA this year. If the agency doesn't overhaul its current method of analysis, supporters of E-Check may want to encourage their lawmakers to dig into the data and judge this program based on its true performance.
contact peter shuler: [email protected]