A Tune Up for Automobile Emission Testing

December 2nd, 1999 by 3 Comments

Kenneth Green

There are only so many ways to improve air quality, and in places like Atlanta, where 30 to 40 percent of the air pollution comes from cars, emission systems maintenance of cars and trucks pretty much has to be part of the prescription. The clean air act requires that polluted areas implement automobile inspection and maintenance programs, and the EPA has its idea of what a ‘gold standard’ program looks like. The problem is, EPA’s one-size-fits-all approach doesn’t work worth a darn.

If traditional annually-test-every-car-at-the-tailpipe programs worked, you’d find more properly maintained cars in areas that ran such programs than you would in areas without them, right? Well, you don’t. If it was just a matter of high tech, you’d expect to find better maintained cars in high-tech testing areas (of the sort that EPA wants for Atlanta) than you do in low-tech testing areas. But you don’t. Finally, if annual testing worked, you’d expect to see the air in an area get cleaner after you start running such a program, right? But you don’t. On virtually every measure, traditional vehicle test and repair programs, whether tailpipe or dynamometer, provide virtually no environmental benefit.

And technological effectiveness aside, there’s the question of targeting. As the saying goes, you only hit the target you aim at. Traditional vehicle testing programs take a shotgun approach to a problem that really needs pinpoint targeting. The problem is that such programs assume every car is equally likely to have a broken emission-control system. But they’re not. Over half the smog put out by the cars and light trucks on the road come from only about 20 percent of the vehicles – generally the oldest and most poorly maintained. By comparison, the other 80 percent are pretty clean, making it a waste of time and resources to test them, since you gain very little bang for the buck cleaning them up. Even though this “gross polluter problem” has been known for a good 10 years now, I/M programs favored by EPA send every car out to be tested, charge every owner a test fee, and sometimes make them get very expensive repairs for very little gain. In fact, at least one researcher has shown that “repairing” a borderline vehicle can make it pollute more rather than less.

Traditional vehicle testing is to like a scheduled drug test that you’d make the entire population take. It’s an intrusive waste of time and money in which the majority of the population, people who are doing no harm, are inconvenienced while those causing the problem have powerful incentives to find a way to cheat the test.

So what’s the alternative? First of all, we can stop wasting ammo on fruitless targets: we can stop wasting our resources testing cars that aren’t likely to be polluting much. We have the technology to cheaply scan a car’s smog level from the roadside, identify the car, and send the owner a notice exempting the car from its next scheduled emissions test. This kind of “clean screen” would cut down on the number of cars we have to test, and let us concentrate on testing the remaining cars more accurately.

Next, we have to target those smoggy cars for repair. That is often portrayed as ethically problematic, since most of the smoggy cars are owned by lower income households who avoid costly repairs for sound economic reasons. But in fact, experience in California shows it’s not that big a problem: when push comes to shove, even low income motorists find ways to get their cars repaired, and preserve their mobility. If some assistance is needed, there are ways to do it. The same roadside scanners checking for clean cars could also send notices out to people whose cars are polluting at high levels, advising them of low-interest loans and extended-payment programs that can help them fix their car. Yes, we’d have to be careful that people didn’t abuse the program, as we do with guaranteed student loans, but there are established methods of doing that, and at least the motorist’s car would be a form of collateral.

Finally, we can get the federal government out of the micro-managing business, and get some flexibility written into the I/M rules so that areas with unique pollution challenges are free to use the best mix of technology and program elements that they can in order to get the best results. That’s only going to happen if more states follow California’s lead and fight for non-traditional vehicle test programs like the one outlined here.

Though it’s in vogue to bash them these days, cars are liberating technology. They give us mobility unparalleled in history, and unrivaled by other countries. Some 87 percent of American households own cars, and rely on them for the benefits of mobility – being able to pick the best job, rather than the closest; being able to pick the best school for the kids, not just the one in walking distance; being able to chain trips together most efficiently to serve ever more complicated, dynamic and fulfilling lives.


Green is the author of Innovative Approaches for Meeting the Georgia Ozone Challenge, a policy study published earlier this year by the Georgia Public Policy Foundation. The Georgia Public Policy Foundation is an independent, nonpartisan organization dedicated to keeping all Georgians informed about their government and to providing practical ideas on key public policy issues. The Foundation believes in and actively supports private enterprise, limited government and personal responsibility.

Nothing written here is to be construed as an attempt to aid or hinder the passage of any bill before the U.S. Congress or the Georgia Legislature. © Georgia Public Policy Foundation (December 2, 1999). Permission is hereby given to reprint this article, with appropriate credit given.

3 thoughts on “A Tune Up for Automobile Emission Testing

  1. I didn’t realize that up to 30 to 40 percent of air pollution comes from cars. It makes sense that regular emissions testing on autos could help better maintain cars and lower that pollution. I will have to get my car tested to make sure I am not contributing to this pollution in a significant way.

    1. We believe broad emissions testing is an inefficient way to combat air pollution. From our recent research, by the numbers …
      13: The number of counties where emissions tests are required of automobiles manufactured between 1993 and 2014 (Cherokee, Clayton, Cobb, Coweta, DeKalb, Douglas, Fayette, Forsyth, Fulton, Gwinnett, Henry, Paulding and Rockdale County).

      $25: The maximum cost of an emissions test.

      998: The number of inspection stations operating for the mandatory annual emissions tests in the 13-county area in 2015, the latest report available.

      584: The number of emissions inspection stations that failed equipment audits. (59 percent).

      2,615,706: The number of automobiles that underwent on-board diagnostics (OBD) emissions testing in 2015.

      208,535: The number of passenger vehicles that failed their initial OBD test in 2015, amounting to 8 percent of the vehicles that underwent OBD testing. Among vehicles manufactured in 2009 and later, however, fewer than four in every 100 failed.

  2. It’s really interesting that over half of the smog that comes from cars comes from about 20% of vehicles, and are usually ones that are poorly maintained. To be honest, I wouldn’t mind wondering what cars like these would have to go through to be better. Not only that, but it would be interesting to see what the smog testing for these vehicles would be.

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