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Evan Horowitz | Quick Study

Are auto inspections worth it?

Tom McCullough of Dorchester waited to get an inspection sticker.
Tom McCullough of Dorchester waited to get an inspection sticker. Globe file, 2000

You were right to grumble, standing in the cold as you waited for your car to be inspected. There’s not much evidence that those $35 annual checks help the environment.

Once upon a time, emissions inspections may have mattered more, back when our air was dirtier, cars were less efficient, and smog seemed a bigger concern than global warming. But the pollution-detection system has outlived its usefulness as the bulk of older, high-polluting cars have been fixed or junked.

And while it’s true that Massachusetts service stations also check a host of other safety issues during those annual visits — seat belts, mirrors, lights — here too the evidence is mixed. While some studies have found that regular safety testing can save lives, others have found no real-world effect.


Let’s take these one at a time: first, the declining importance of emissions testing; second, the uncertain impact of safety testing.

The reason Massachusetts introduced an annual emissions testing program, in 1999, was because tailgate pollutants were producing smog and generally poisoning our air. With the Federal Environmental Protection Agency declaring Greater Boston and other areas of the state out of compliance with federal clean air laws, it made sense to identify and fix cars spewing carbon monoxide and nitrogen oxide.

It’s possible — though unproved — that the emissions testing program made a difference in those early years. Something certainly did, because these days Massachusetts has some of the cleanest air in the country, according to a report from the American Lung Association, with just one county still cited as being below EPA standards (Martha’s Vineyard.)

But even if that’s true, it doesn’t mean annual emissions testing remains vital, or even necessary.

The most substantial gains seem to involve the oldest cars. A pair of researchers from Cornell University and the Consumer Financial Protection Bureau recently released an analysis of a similar program in California, which found that while inspecting cars made before 1985 substantially reduced area pollutants, testing newer cars didn’t have much impact, thanks to such technological changes as improved catalytic converters and fuel-injection.


In fact, over time the emissions program has gotten steadily less important, as older cars have increasingly been modified or scrapped.

If anything, Massachusetts’ program is likely to be less effective than its California peer, because we don’t even test older vehicles. After 15 years, cars no longer get rigorous emissions tests, just an eyeball assessment of whether smoke billows from the tailpipe.

Abandoning emissions testing altogether might be a step too far. At the very least, we need some mechanism to ensure that car companies are complying with pollution regulations and not flouting rules the way Volkswagen did by rigging its cars to be less noxious in tests than they were on the road.

But the fact that Volkswagen was able to game the emissions testing equipment shows that this may not be the best deterrent. Rather than forcing everyone to bring their cars in for an artificial performance assessment, government agencies could purchase sample cars for testing or pay willing drivers to participate in real-world testing programs. Indeed the US Environmental Agency does just that on heavy-duty diesel and small gasoline engines, simulating real-world conditions, and expanded the program in the wake of the VW scandal.


Setting emissions aside, it’s also true that cars in Massachusetts undergo a thorough safety inspection as part of their annual check-up, to ensure that no potentially-dangerous modifications have been made — like tinting — and that key systems are functioning properly: brakes, suspension, lights, air bags, horn.

But while this may seem like common sense, the real-world benefits have been surprisingly hard to pin down.

Take a 2009 study from the Medford-based transportation consultants at Cambridge Systematics. They found that states with safety-inspection programs do have safer roads, with fewer fatal crashes. But even they acknowledge that a broader look at the literature shows a muddier picture. Some studies find big impacts, others find no impact, such that “no definitive conclusion can be made from the previous literature regarding the effectiveness of state vehicle inspection programs.”

And if that sounds surprising, it’s worth remembering that even without safety inspections, most of us already have pretty good incentives to keep our vehicles in decent working order — maintaining their value and avoiding police citations.

Plus, if road safety is really a top concern, there are a lot of other, proven approaches. We could use the money to improve bus service, which a 2014 study in the Journal of Public Transportation found to be 60 times safer than car travel. Or we could save lives by lowering speed limits, as London did by increasing the number of 20 mile per hour zones and consequently reducing traffic casualties by more than 40 percent.


Given these alternatives, and the tens of millions of inspection-funding dollars on the line, it’s surprising the annual auto testing regimen gets so little critical attention.

Partly, it may be because inspections can be a genuine boon for service stations, particularly when failing cars stay on the lot for repairs. But if we’re testing cars as part of a jobs program for the auto service industry, perhaps we should be honest about that.

Otherwise, it may be time for reforms.

We could start by switching to biannual testing, which AAA reports is the norm in lots of other states. Then maybe Massachusetts can undertake a full cost-benefit analysis to see whether we should discontinue testing or refocus on those elements that are research-tested and safety-proven.

For now, however, change seems unlikely. Just last year the state signed a new, five-year contract to extend the current process with updated technology.

Evan Horowitzcan be reached at evan.horowitz@globe.com. Follow him on Twitter @GlobeHorowitz