Amendments made to the Clean Air Act in 1990 require a number of states with particularly high levels of pollution to conduct more comprehensive, or "enhanced," auto emissions inspections and to submit an evaluation of the effectiveness of their programs to the Environmental Protection Agency (EPA) every two years. But the National Academy of Sciences dismisses the tests as an ineffective and costly burden to drivers.

In a new report, the research group finds that for the vast majority of car owners emissions testing is a waste of time and money.

• Utilizing cleaner technologies, newer cars almost never fail the emissions tests -- with 99 percent of 1995 model-year cars passing in Arizona, for example.

• Just 10 percent of cars built before 1990 contribute up to half of emissions.

• As it stands now, 10 percent of vehicles required to undergo emissions testing never show up for inspection, while 10 percent to 27 percent of vehicles failing inspection never end up passing the test.

• Because many cars with high emission rates are owned by low-income families, most states simply give owners a waiver if repair bills are too great.

Rather than subjecting the overwhelming majority of owners of clean cars to the hassles of testing, recent model cars should be exempted from testing, and on-road pollution detectors could be used to identify the small number of cars emitting pollutants. Advocates of this approach say it would free up millions of dollars to help the poor with the costs of repair.

Source: Editorial, "EPA, States Cling to Flawed Emissions Tests," USA Today, July 26, 2001; based on "Evaluating Vehicle Emissions Inspection and Maintenance Programs," Committee on Vehicle Emission Inspection and Maintenance Programs, Board on Environmental Studies and Toxicology, Transportation Research Board, National Research Council (Washington, D.C.: National Academy Press, 2001).

For NAS report http://www.nap.edu/books/0309074460/html/