49ºF

Can an air purifier kill COVID-19?

FILE - This 2020 electron microscope image provided by the National Institute of Allergy and Infectious Diseases - Rocky Mountain Laboratories shows SARS-CoV-2 virus particles which causes COVID-19, isolated from a patient in the U.S., emerging from the surface of cells cultured in a lab. On Monday, Oct. 5, 2020, the top U.S. public health agency said that coronavirus can spread greater distances through the air than 6 feet, particularly in poorly ventilated and enclosed spaces. But agency officials continued to say such spread is uncommon, and current social distancing guidelines still make sense. (NIAID-RML via AP)
FILE - This 2020 electron microscope image provided by the National Institute of Allergy and Infectious Diseases - Rocky Mountain Laboratories shows SARS-CoV-2 virus particles which causes COVID-19, isolated from a patient in the U.S., emerging from the surface of cells cultured in a lab. On Monday, Oct. 5, 2020, the top U.S. public health agency said that coronavirus can spread greater distances through the air than 6 feet, particularly in poorly ventilated and enclosed spaces. But agency officials continued to say such spread is uncommon, and current social distancing guidelines still make sense. (NIAID-RML via AP)

Concern over COVID-19 has many people worrying about indoor air quality and whether an air purifier can help. Consumer Reports' experts reveal what a residential air purifier can really do when it comes to cleaning the air.

The HEPA filters in most residential air purifiers are certified to capture 99.97% of particles that are 0.3 micron in diameter. They also capture smaller and larger particles even more efficiently, including the coronavirus.

If someone in your household is sick, he or she should be isolated in a separate room with an air purifier. Even then, an air purifier isn’t a cure-all.

The faster an air purifier can exchange air in a room, successfully passing it through its filter, the better its chances of capturing the virus-laden particles. But even then, it’s not going to eliminate all of the particles, nor will the filter capture viruses that have landed on surfaces in the room.

CR says that along with the use of an air purifier, people should continue to practice social distancing, wear protective face masks, and follow other guidelines provided by the CDC.

The Blueair Classic 605 for $830 is the best and fastest air purifier based on CR’s particle reduction tests. But it’s pricey, and noisy at its highest speed.

For less money, consider the Honeywell HPA300 for $220. It earned ratings of Excellent and Very Good at its highest speed and lowest speed, respectively.

CR says you can see how fast an air purifier cleans the surrounding air by looking for its CADR number—or clean air delivery rate—on the packaging. Choose a model with a CADR over 240. This means that a particular air purifier can perform about five air exchanges per hour in its suggested room size. Also, remember that simply opening your windows will allow fresh air to flow in and can help clear the air in a room.

Consider an air purifier for smoke and dust

The recent wildfires in the U.S. have created hazardous air-quality conditions across vast stretches of land. Even people who aren’t affected by the fires are now thinking about smoke and dust pollution. Could an air purifier help?

As of early October, wildfires had burned more than 4.1 million acres across the U.S., including more than 2.6 million acres in California alone. Even if you live far away from the fires and aren’t in immediate danger, smoke can travel hundreds—even thousands—of miles from the source. But can an air purifier help clean up indoor air?

An air purifier is actually your first line of defense when it comes to smoke caused by wildfires. And CR says it’s not just wildfire smoke that’s concerning. Indoor sources like fireplaces, candles and incense, and even nearby pollution outside can affect indoor air quality.

In its laboratory tests of air purifiers, CR injects contaminants like smoke and dust into a controlled chamber to see how well a unit reduces the number of particles in the air. The faster an air purifier can remove those particles, the better the score.

The Blueair Blue Pure 211+ for $300 earns a rating of Excellent for clearing out smoke particles at all of its three speeds. For less money, and if you can stand a bit of noise, CR recommends the Honeywell 50250 for $220. It’s a very cost-effective air purifier.

The best thing you can do is to use an air purifier with other methods that help improve indoor air quality.

To maximize the effectiveness of an air purifier, follow these tips:

Close all of your windows and doors tightly, and seal any air leaks with weather stripping or even masking tape if that’s all you’ve got.

Try spending the bulk of your time in a room with as few windows as possible. That room shouldn’t have a fireplace or anything else that vents to the outside. Use an air purifier in the room, keep it running 24/7, and change the filter as soon as the indicator light comes on. If you can’t change it right away, keep it running; a dirty filter is better than no filter.

CR says that while a HEPA filter is great for reducing smoke particles, it won’t remove smoke odors. For that, be sure your purifier also has a large carbon filter. The filter for the recommended Blueair model contains activated carbon, which can help with smoke odors. The Honeywell also contains a carbon filter. Both air purifiers also have filter indicator lights.