What Is a HEPA Filter

A genuine HEPA filter captures at least 99.97% of particles 0.3 microns across, and the label to trust prints that percentage. "HEPA Type" and "HEPA Like" print no such figure, so an air purifier carrying them has made no HEPA promise.

Hepa Filter Air Purifier

HEPA stands for high efficiency particulate air, and a HEPA air purifier uses a filter built to meet the 99.97% at 0.3 microns standard. That size is the hardest to catch, so larger and smaller particles are trapped at even higher efficiency.

One look-alike is not a look-alike: a label that says H13 or H14 is a graded claim. H13 captures at least 99.95% of particles at the most penetrating size, and H14 must reach 99.995% at the most penetrating size. If your unit carries one of those grades, keep it.

• Your label says "HEPA Type" or "HEPA Like", or prints no percentage at all: that wording conforms to no standard. Replace the unit with the Levoit Vital.
• You own a Dyson, or you're looking at one: the TP10, TP11, TP12, TP14, BP10-A and SP01-B are CARB-listed mechanical models. Check the unit for 99.97% at 0.3 microns, and if it isn't printed, get the Vital.

The Vital is the Levoit air purifier we'd put first. Its page states a main HEPA filter at 99.97 percent of 0.3-micron particles and a room size of 388 sq ft at 4.8 air changes per hour. Levoit rates its CADR at 250 CFM, and Air Purifier First's figure is 245 CFM. If you have pets, its washable pre-filter suits the job.

If you want to compare models beyond HEPA labels, see the best air purifier.

If you're shopping for a sleeping space, see the best air purifier for bedroom.

Do HEPA filters remove mold?

A HEPA filter captures airborne mold spores, which run from 2 to 100 microns, but it won't touch the mold growing in your home. Air cleaners will not prevent mold growth, because the cause is moisture. Fix the water problem and clean the mold up. A moldy patch larger than about 10 square feet calls for a remediation professional.

Can I wash a HEPA filter?

No. The Winix 5530's carbon and HEPA filters must not be washed, and the washable part on the Levoit Vital is its pre-filter. Replace a HEPA filter on schedule: a dirty, overloaded filter won't work well.

Is a HEPA filter good for COVID?

A HEPA filter alone is not enough: EPA says air cleaning by itself is not enough to protect people from COVID-19, and it works alongside source control and ventilation. A purifier filters airborne particles. A medical condition needs a doctor.

Hepa Filter Vacuum

The same label test applies to the vacuum in your closet, and the vacuum's real job is settled dust and dander.

Once the label checks out, remember what the vacuum is for. A purifier cannot remove allergens already settled on carpets, bedding or upholstery. Vacuum those surfaces, wash the bedding, and let the purifier handle what's in the air.