If you’re allergic to pollen, autumn—the peak of ragweed season and the reintroduction of mold spores from fallen leaves—can be both a beautiful time of year and an ugly reminder that seasonal allergies have the propensity to stifle your fun.
Closing your windows can help keep some of those outdoor agitators at bay, but indoor pollutants, such as dust and mold, are ever-present in our living spaces. Without fresh air cycling through your home, air pollution indoors can reach concentrations five times higher than outdoors, according to the Environmental Protection Agency. A good air purifier can reduce some of those pollutants and help you breathe easier.
“The best air purifiers we’ve tested are able to remove small particles from your air whether at high or low speed,” says Misha Kollontai, who oversees testing of air purifiers at CR. “They are able to do so at a relatively low noise level, which is great since they are operating around the clock.”
On the flip side, Kollontai observes that the worst air purifiers on our list struggle to clean the air on both low and high speeds, adding, “Oftentimes, poor performance in removing particles like smoke and dust is accompanied by a lot of noise, which can be bothersome in a living area.”
To test air purifiers, we inject smoke and dust particles into a sealed chamber and measure how well each model removes particles between 0.1 and 1 micron. (Human hair has a diameter of 100 microns.) We use a particle counter to measure the change in particle concentration as the air purifier runs for 15 minutes at the highest speed, and then at a lower speed. And because these run day and night, we measure noise levels, in decibels, at every speed, and calculate annual operating costs for filter replacements and energy use to run the machine 24 hours a day.
The three top models in our air purifier ratings earn an Excellent or Very Good rating for particle reduction at a low speed while keeping noise to a minimum. (They all aced the high-speed test, as do many models.)
Here’s a closer look at the three best air purifiers we tested, followed by the three worst. They’re listed alphabetically.