Take a deep breath—if you can. Many of the things we do to keep energy costs down, such as fixing drafty doors and leaky windows, can also seal in pesky pollutants and irritants. Many people who buy air purifiers do so in hopes of easing asthma or allergies. But despite product claims, there’s little definitive medical evidence that air purifiers help to relieve respiratory symptoms.
Improving indoor air quality starts with minimizing pollutant sources such as cigarette smoke, dust, and pet dander. We test how well a room air purifier removes dust and smoke from an enclosed space, how it performs at high and low speeds, and how quiet it is.
The very best portable models we tested were effective at cleaning the air of dust, smoke, and pollen at their highest and lowest speeds. The worst models weren’t terribly effective at any speed.
How We Test Air Purifiers
At Consumer Reports, all our air-quality testing is conducted in a 12x18-foot sealed room isolated from the rest of our labs. To test how well air purifiers clean the air, we place the air purifier in the center of the room and inject cigarette smoke and dust into the room through a tube. We then use a machine that analyzes the particles in the air and measures the change in the air particle concentration over a 15-minute period at both the air purifier’s high and low speeds.
To measure noise, we use a decibel meter at ear level 4 feet in front of the air purifier and record the noise level at high and low speeds for each model. The annual cost is a combination of filter replacement costs and the energy required to run the purifier 24 hours a day for an entire year.