As the owner of an air purifier, I’ll admit the common suspicion of them has crossed my mind: is this thing actually doing anything, or is it just a soft droning background hum tricking me into thinking it’s doing something?  

New research published in Scientific Reports suggests that, yes, it is doing something, and that includes protecting you from toxic pollutants that could ravage your brain, especially if you’re over 40.

The study from researchers at the University of Connecticut and Tufts University suggests that pollution seeping indoors from nearby roads, especially highways, may be degrading cognitive performance. The HEPA filter inside your air purifier could help reduce that damage.

The study focused on adults living close to major roadways, where traffic pollution regularly sullies indoor air. The study participants used a real HEPA purifier for one month and identical -looking fake purifiers for another month. The results weren’t glaringly obvious, but enough to be noticeable.

They found that among adults 40 and older, performance on a cognitive test measuring mental flexibility and task switching improved by about 12 percent when real HEPA filtration was used. That’s the kind of thinking you rely on when you’re juggling tasks at work.

Do Air Purifiers Work on Young People Too?

Younger study participants didn’t show too many meaningful changes, and the overall results weren’t definitive across all groups studied. But, the researchers say that the pattern aligns with a growing body of research that says the fine and ultrafine pollution particles given off by cars along major roads can affect higher-level brain function, potentially damaging areas tied to complex thinking.

They also found that HEPA filters reduced indoor particle pollution by quite a bit, over 50 percent for fine particles. So even if you’re not living near a major roadway, these air purifiers are still doing their jobs of protecting your lungs and brain from damaging particles.

It was a relatively small study and the demographics were quite as widespread as you’d like, but they do add more evidence to a growing pile that suggests that a simple little HEPA air purifier in your home can work wonders for cleaning up potentially harmful particles, bringing us all collectively one step closer to proving that that the machine making that weird hum in the corner of your living room might not be so pointless after all.