Questions, answered
Short answers, with links to the full guides.
Air purifiers
EPA says HEPA stands for high efficiency particulate air filter, as officially defined by the U.S. Department of Energy, and that it can theoretically remove at least 99.97% of particles with a size of 0.3 microns.
EPA says the clean air delivery rate helps you match an air cleaner to the size of the room; the higher the CADR, the larger the area it can serve.
Cost
Room size and CADR, filters, energy use, and features. We give no prices.
No. EPA says the label does not refer to air-cleaning effectiveness in any way.
Health and ozone
No. EPA says no federal agency has approved them for use in occupied spaces, and that ozone can damage the lungs when inhaled.
We do not say any air purifier treats allergies or asthma. EPA's answer to whether air cleaners help is "Possibly": it says studies with portable HEPA air cleaners have found improvements in one or more allergy and/or asthma symptoms, but not in all symptoms. Talk to your doctor.
About us
No.
No. We explain what drives cost.
No. Follow the maker's manual, or EPA's own pages for DIY air cleaners.
Some links may be affiliate links.
Health line
General information only. An air purifier is not a substitute for ventilation, for removing the source of a pollutant, or for medical care. Read and follow the maker's manual. The California Air Resources Board strongly advises against the use of ozone generators in spaces occupied by people or animals. If you have asthma, allergies, or heart or lung disease, talk to your doctor. During wildfire smoke, follow local officials and be ready to evacuate. In an emergency, call 911.
