Q: As someone who recently moved to Washington, I was surprised that there are no safety inspections. Wouldn’t we all be safer if all the cars on the road had properly operating lights and regulation equipment? Why are there no safety inspections as in other states?

A: Yes, vehicle inspections increase safety, but we can’t tell you how much. That was the conclusion of a study by the U.S. Government Accountability Office. It’s hard to know if we should or shouldn’t do something when we don’t know how much it helps.

I can’t say for sure why Washington doesn’t have safety inspections, but I can explain why more states used to have them than do now. Money. The federal government used to withhold a percentage of highway funds from states without vehicle inspections. At the peak, 31 states had vehicle safety inspections. Washington was not one of them.

In 1976 that rule changed, and now there are 16 states with annual or biannual inspections. States that still have inspections point out that they make their roads safer. States that have eliminated them say that the cost doesn’t justify the small (or possibly non-existent) increase in safety.

States without inspections don’t seem to have more fatal crashes than those that do. Washington has a lower traffic fatality rate than 10 of the 16 states with safety inspections. But maybe it does matter. The failure rates in Pennsylvania and Virginia are 20 percent and 19 percent. For drivers who fail, the options are fix it or park it. In states without inspections, presumably those cars needing repairs keep driving around.

There are many factors that influence crash rates; it’s hard to identify the impact of any one prevention effort. Not everyone with an unsafe car will crash, just like drivers also don’t crash every time they speed or pick up their phone, but it does shift the odds against them. Given that driving is the most dangerous thing most of us do on a regular basis, it’s worth it to try to lower your odds of a crash.

I don’t know exactly how many fatal crashes include mechanical failure as a factor; various data sources range from 2 percent to 13 percent. Even if that number is underreported (it probably is), compared to high-risk driving behaviors like impairment, speeding and distraction, a car in disrepair ranks relatively low.

However, the timing of this question makes it more interesting. Right now there’s a bill being considered by our state legislators that would prevent law enforcement from making traffic stops for equipment violations, except to “protect against an immediate, serious threat” to safety. In a state like ours without vehicle inspections, traffic stops are currently the only way of enforcing equipment violations.

States that have canceled their safety inspection programs could look to law enforcement to make up some of the difference (although it’s nearly impossible to evaluate much of a vehicle’s roadworthiness while it’s driving down the road.) What happens if that’s not an option here?

I’m just a traffic safety nerd; I have no control over the enforcement of equipment laws, either by traffic stops or by establishing vehicle inspections. Instead, I will make this request: Periodically check your vehicle to make sure it’s safe. The top three equipment failures contributing to fatal crashes are tires, brakes and steering, so you might start there. It’s important to see and be seen, so check your headlights, tail lights, brake lights and turn signals. That small investment might pay big dividends when the line between crashing and making it home hinges on your car’s reliability.

Doug Dahl writes a weekly column for this newspaper. He is with the state Traffic Safety Commission.