Deep Breaths

Air purifiers with HEPA filters can be used as part of a strategy to reduce the likelihood of Covid-19 transmission indoors. However, in temperate climates like the Central Coast, getting as much fresh outdoor air inside – either by opening a window or positioning a fan – is another good option.

WHEN THE CONSUMER ELECTRONICS SHOW TOOK TO THE VIRTUAL STAGE EARLIER THIS MONTH, COVID-19 LOOMED LARGE. And not just because the annual gadget show’s attendees were at home instead of crowding into Las Vegas conference centers – the ongoing global pandemic also made an impact on the types of products on display. “Smart” face masks, air purifiers and other health-related technologies were all the rage. Companies showed off tiny air purifiers meant for traveling, air purifiers that somehow use “natural biotics and enzymes derived from nature” to clean the air and air purifiers that boast washable filters meant to help cut back on waste. Some made promises about helping prevent the transmission of Covid-19, others did not.

All this creates a confusing situation for would-be consumers. Can an air purifier prevent the spread of Covid-19? And if it can’t, should I still get one?

“There are numerous devices being heavily marketed to provide air cleaning during the ongoing Covid-19 pandemic,” the U.S. Centers for Disease Control report in a Q&A on ventilation. “In the absence of an established body of peer-reviewed evidence showing proven efficacy and safety under as-used conditions, the technologies are still considered by many to be ‘emerging.’ As with all emerging technologies, consumers are encouraged to exercise caution and to do their homework.”

The “homework” the CDC recommends involves requesting, and investigating, the testing data available for these devices. Short of that tall order, however, there are still simple strategies for improving indoor air quality.


“We’ve got this big crisis and you’re telling me to open up a window? Yes, I’m telling you to open up the window,” Dr. Anthony Fauci, the nation’s most visible infectious disease expert, said in August 2020 while on a panel at Harvard’s T.H. Chan School of Public Health.

Locally, Bill Hayward is a ventilation enthusiast. He’s not suggesting that opening a window will eliminate coronavirus, but that introducing more fresh air into an indoor space on a regular basis will remove any Covid particles that might be hanging around more frequently and therefore lessen the chance you come into contact with one. When experts consider ventilation, they think about air changes per hour (ACH), says Hayward, CEO of Hayward Lumber and founder of Hayward Healthy Home, which specializes in healthy indoor air quality.

In essence, ACH is the rate at which air in a given space is completely recycled. Currently, the guidelines from the American Society of Heating, Refrigerating and Air-Conditioning Engineers state that homes should get at least 0.35 ACH, or about one change every three hours. But according to Hayward’s current (and ongoing) research, the need for much more – around 6 ACH.

In addition to simply opening a window, you can also boost ventilation in a space by positioning a fan in or near a window so that it drags outdoor air inward. Hayward is quick to point out that ventilation isn’t just useful for combating Covid-19. Studies have shown that good ventilation increases cognitive function and productivity, which he sees as a potential legacy benefit of the current interest in ventilation.

“Ventilation really is, I think, the new frontier of human health,” Hayward says.


There’s also a role for air purifiers, though it’s important to note that air purifiers alone do not protect against Covid-19. According to the U.S. Environmental Protection Agency, air purifiers “can help reduce airborne contaminants, including viruses, in a home or confined space.” Because viruses such as the one that causes Covid-19 are very small particles, the CDC recommends air purifiers with High-Efficiency Particulate Air (HEPA) filters which are effective at capturing particles that are as small as 0.01 micron in diameter.

“Portable HEPA filtration units that combine a HEPA filter with a powered fan system are a great option for auxiliary air cleaning, especially in higher risk settings such as health clinics, medical testing locations, workout rooms or public waiting areas,” the agency writes. Keep in mind that the exact type of filtration system needed will depend on the size of the indoor space. As with fans the positioning of the device is also important – it shouldn’t blow air from one person directly at another, for example.

Like ventilation, air purification has an auxiliary benefit – better indoor air quality helps support your health whether or not Covid-19 is present. For this reason, Monterey Bay Air Resources District’s Richard Stedman recommends that people ventilate appropriately when cooking with gas, be on the lookout for mold issues and consider removing carpeting that houses dust in favor of easily-cleaned wood or linoleum surfaces.

“If you’re exposed to pollution, and other types of pollutants either in the home or outside of the home and you compromise your lung function, then you’re more susceptible to Covid,” Stedman says.

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