A Smart Decision on Auto Smog Checks

Last week’s decision by the U.S. Environmental Protection Agency to relax its rules governing auto emission inspections was perhaps inevitable. Not just because the new Republican majority in Congress may signal a less tolerant attitude toward environmental regulations. Not just because the proposed federal scheme, which relied heavily upon centralized testing stations, could prove enormously inconvenient and hence, enormously unpopular. And not just because some states were so resistant to the federal rules that they seemed willing to violate them and lose highway funds and other federal aid.

Rather, in loosening its widely criticized smog rules, the EPA appears to have also recognized that its rules rest on an unsteady scientific foundation; research in recent years has revealed substantial uncertainty about which cars really cause how much smog and under what conditions. For this reason, the EPA’s decision was not only politically inevitable but technically appropriate.

EPA Administrator Carol Browner has reportedly told a group of governors that they can employ options other than central test stations to meet new vehicle-testing regulations, as long as the overall pollution-reduction levels mandated by the 1990 Clean Air Act are met. For example, a state could require that only older, presumably dirtier-running cars go to a central inspection station. Or a state could choose simpler, less costly testing equipment that might not screen cars as well.

Browner’s decision means that California can proceed with its plan, beginning next year, requiring initially that only 15% of all cars be tested at the special centers; the others would continue to go to service stations for smog checks.

The EPA announcement seems an acknowledgment of the substantial scientific uncertainties that dog the 10-year old smog-check program in California and its counterparts in other states. Emissions from mobile sources, primarily cars, may be far higher than once thought.

But cleaning up dirty cars eludes such easy or blanket solutions as central test stations. Most mobile-source emissions come from perhaps 5% to 10% of cars on the road, the so-called “gross polluters.” Most of these are older cars, but not all of them. No one fully understands what causes some cars to become gross polluters. Moreover, the same car might pass a smog inspection one day and fail the next.

The EPA’s decision on emission rules signals its ability to read the political tea leaves. But the agency and individual states should now take the opportunity to advance the scientific understanding of auto pollution and the search for more effective--and palatable--regulatory schemes to cut smog.