How Do I Choose an Air Purifier?

Pick an air purifier by room size, not by the marketing headline on the box. EPA says portable air cleaners are meant for a single room or area, and the clean air delivery rate, or CADR, should be large enough for that space. If the purifier is too small, it will run constantly and still underperform.

For particles like dust, pollen, and smoke, HEPA matters. EPA defines HEPA as a filter that can remove at least 99.97% of particles at 0.3 microns under test conditions. That makes it a strong starting point if allergies or wildfire smoke are part of the problem. For odors and gases, look for a purifier that explicitly handles those too; a particle filter alone will not do everything.

The last filter is practical, not technical: noise, energy use, and replacement cost. A purifier that is perfect on paper but annoying to sleep with will end up unplugged in a closet. If you want a quick starting point, search for a room-sized HEPA purifier: portable HEPA air purifier.