Vehicle inspection programs: Worthwhile, but repairs are needed
by Ralph J. Cicerone and David T. Allen
t's summertime, and for many urban areas, that means smog season. From Los Angeles to New York, and many points in between, people are suffering through code red days, when levels of harmful ozone are so high that people are urged to stay indoors and to avoid driving if possible. As most people know, vehicle emissions are a major source of the chemicals that create smog. And even though today's vehicles and fuels are far cleaner that those of 25 years ago, there are simply more cars and trucks on the road. Pollutants in vehicle exhaust have also been linked to serious respiratory and other health ailments, as well as a host of environmental ills including global warming.
That is why the federal government has implemented a number of programs to reduce vehicle emissions including vehicle inspection and maintenance programs. Overseen by the US Environmental Protection Agency and implemented by states, mandatory inspections are conducted in over 30 states whose jurisdictions violate federal clean air standards. The programs vary from state to state, but they typically involve regularly scheduled exhaust tests, which measure emissions of carbon monoxide, hydrocarbons, and in some cases nitrogen oxides.
The programs have the potential to reduce emissions by persuading motorists to do a better job of maintaining their vehicles and repairing faulty pollution-control systems. But the inspections have been criticized by some policy-makers and citizens. State-sponsored evaluations show that computer models used by the EPA and state agencies overestimate the reduction in vehicle emissions that can be credited to inspection and maintenance programs. What's more, many motorists view the programs as a nuisance and question whether they're needed at all, given the improved emission-control technologies available in many of today's vehicles.
We recently led a committee of the National Research Council that examined the effectiveness of vehicle inspection programs. The committee concluded that, despite certain flaws, these programs are necessary for reducing vehicle emissions and improving air quality, although they need some major changes to make them more effective at reducing air pollution.
Most states use too many resources inspecting newer cars, which have the latest pollution control technologies and relatively low emissions. However, malfunctioning vehicles, which make up only about 10 percent of the nation's fleet, typically emit about 50 percent of most harmful air pollutants from motor vehicles. If state emissions programs are to achieve progress in reducing air pollution, they must make these malfunctioning vehicles their primary target.
We realize that focusing on these high emitters raises legitimate concerns about fairness. Many malfunctioning vehicles are owned by people with limited economic means. As it stands now, a significant number of vehicles failing inspection never end up passing the test. Since many of the owners of these cars probably cannot afford to fix them, states should consider policies that would provide financial relief or other incentives so owners will obtain long-lasting repairs or replace faulty vehicles. There also is growing evidence that less testing of vehicles with a low probability of failure including exemptions for testing recent-year models could be very cost-effective, as well as reduce the testing burden on the public.
Part of the credibility problem for vehicle inspection and maintenance programs lies in the computer models used to predict emissions reductions. These predictions are used to determine the emission-reduction benefits of inspection and maintenance programs. But states and the EPA are allowed to use overly optimistic assumptions about the performance of the inspection and maintenance programs in the models. When data collected from on-road vehicles are used to assess the performance of the inspection and maintenance programs, emissions reductions are found to be much smaller than predicted by the models.
EPA grants emission-reduction credits to states for demonstrating compliance with air-quality standards by adopting programs such as vehicle inspections. These credits should be closely tied to actual reductions, based on observational and empirical data, not just projections from models. And a new rule issued by EPA requiring states to use on-board diagnostic systems for testing cars and trucks should be independently reviewed. Although these systems are designed to alert drivers about potential problems with exhaust and emission-control components, they do not actually measure emissions, and preliminary studies indicate significant technical problems with using on-board diagnostics for testing.
Clearly, vehicle inspection and maintenance programs need a lot of improvements. But if the programs are properly designed and administered, they could go a long way toward reducing air pollution cost-effectively.
Ralph J. Cicerone, chancellor of the University of California in Irvine, and David T. Allen, Reese Professor in Chemical Engineering and director of the Center for Energy and Environmental Resources at the University of Texas in Austin, were chair and vice chair of a committee of the National Research Council that wrote the recent report Evaluating Vehicle Inspection Emissions and Maintenance Programs