Air Purifiers
The right air purifier is the one whose CADR fits your room. AHAM suggests a smoke CADR of at least two-thirds of the floor area, so a 300 sq ft bedroom needs a smoke CADR of about 200. Size first, then compare noise and filter cost.
How to choose an air purifier
- CADR: compare smoke, dust and pollen numbers from the AHAM Verifide program rather than box claims of "up to" a large area.
- Filter: a true HEPA filter captures 99.97% of particles at 0.3 microns. You need an activated carbon stage for smoke smell and cooking odors.
- Noise: for a bedroom, look for a low setting of roughly 25 to 35 dB.
- Running cost: replacement filters usually cost $30 to $150 a year, depending on size.
- Ozone: pick a model on California's CARB certified list, or one where the ionizer can be switched off.
Shop by need: Air Purifiers for Allergies, Air Purifiers for Smoke, Large Room Air Purifiers and Bedroom Air Purifiers. You can also browse True HEPA Air Purifiers by price or start from our Air Purifier Brands hub for Winix, Coway, Levoit and Blueair.
FAQs
What size air purifier do I need?
Use AHAM's two-thirds rule: the purifier's smoke CADR should be at least two-thirds of the room's floor area in square feet. A 12 x 15 ft room (180 sq ft) needs a smoke CADR of about 120. Many buyers size up one step so the unit can clean the room on a quieter fan setting.
Do air purifiers actually work?
According to EPA guidance, portable air cleaners with HEPA filters reduce airborne particles such as dust, pollen, pet dander and smoke in the room where they run. They remove gases only if they have a substantial carbon filter, and they do not clean dust that has already settled, so vacuuming and ventilation still matter.
How often should I replace an air purifier filter?
Most manufacturers recommend replacing the HEPA filter every 6 to 12 months and carbon or pre-filters every 3 to 6 months, depending on hours of use and air quality. Filters load faster during wildfire season. Follow the filter indicator and check the part number on the back of your unit before you reorder.
Are air purifiers with ionizers safe?
Ionizers and PlasmaWave-style features can produce small amounts of ozone, a lung irritant. California requires air cleaners sold in the state to emit no more than 0.050 ppm of ozone. If you want to avoid ozone, choose a CARB-certified model or one with an ionizer you can switch off, as on most Winix units.
