Another study has come out confirming what we knew, but offering more and better evidence: ignition interlocks are an anti-drunk driving measure that works.

A peer-reviewed ignition interlock study, recently published in the American Journal of Public Health, confirms and reinforces the case for ignition interlocks – car breathalyzers which prevent a vehicle from starting if the driver has been drinking. The devices are ordered by a court or DMV after a drunk driving arrest or conviction.

Researchers from the University of Pennsylvania examined data from the National Highway Traffic Safety Administration (NHTSA) data to compare alcohol-related crash deaths in states that required ignition interlocks for all those convicted of DUI as of 2013 with those that did not mandate interlocks.

The results were telling: states that required interlocks saw a 15 percent decline in alcohol-related road deaths. This number is comparable to the number of lives saved by airbags each year.

The ignition interlock study notes that previous research focused on DUI recidivism, reminding us that “interlocks have been shown to reduce drunk-driving recidivism by 50% to 90% while installed.” This study, however, focused on lives saved rather than crimes repeated.

The conclusion of the study is worth noting:

Our study provides support for continued expansion of interlock programs and innovation in the use of interlocks to reduce drunk driving crash fatalities.

It’s fair to say, then, that the results are in, and they favor mandating ignition interlocks for all drunk driving offenses as a way to prevent needless road deaths.

If you’re concerned about road safety in your state, make sure your legislators know about this study. Passing it on could save lives.