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Experts say opening windows and using fans may be a cheaper alternative to air purifiers. Getty Images
  • Experts say air purifiers may not be that effective at preventing the spread of the novel coronavirus in places such as classrooms and offices.
  • They say safety precautions such as mask wearing and physical distancing are the best prevention measures.
  • They add that opening windows and using fans can be a cheaper alternative.

As the number of COVID-19 cases remains manageable in most of the United States, people are looking to get back indoors, whether that’s returning to the office after more than a year of remote work or sending the kids back to school for in-person instruction.

But people want those areas to be as safe and clean as possible, especially the air they’ll be breathing for hours on end.

There are numerous air purifiers on the market that claim to help clean the air of the novel coronavirus, often using technology that sounds like it would be able to take down any microbe.

Many lack real-world specific scientific rigor to back up their marketing claims and the Environmental Protection Agency (EPA) says they’re most likely inadequate against the coronavirus.

“By itself, air cleaning or filtration is not enough to protect people from COVID-19,” the EPA says on its website.

However, that’s not stopping people from seeking costly solutions rather than continuing to follow low-cost preventive measures.

Kaiser Health News recently dug into the frenzy of schools buying air purifiers that boast using technology such as ionization, plasma, and dry hydrogen peroxide, which the Lancet COVID-19 Commission said is “often unproven” and can actually pollute the air.

The Kaiser Health News investigation found that these products can lull students, teachers, and staff in those schools into a sense of false security. This comes as contractors look to make money following a flood of federal grants to improve schools’ air supply systems in response to returning to in-person instruction.

Public health experts note that the novel coronavirus transmits best when people gather indoors without masking or physical distancing for 15 minutes or more at a time.

Filtration systems are important in places where people sit in recirculated air for sometimes hours at a time, such as on an airplane, but experts are saying they’re not the next phase of COVID-19 prevention.

“Certainly, the air purification systems on commercial airplanes are helpful in reducing the spread of COVID-19, but it is unlikely you would purchase such a sophisticated system for your home, school, or office,” said Dr. David Cutler, a family medicine physician at Providence Saint John’s Health Center in Santa Monica, California.

Experts say that simple interventions with minimal investment can make for much less costly solutions to increase airflow in buildings.

“Just open windows,” Dr. Amesh Adalja, an infectious disease expert and senior scholar at Johns Hopkins Center for Health Security in Maryland, tweeted on May 3.

Besides opening windows, the Centers for Disease Control and Prevention (CDC) recommends other no-cost interventions, such as inspecting and maintaining dedicated exhaust ventilation, disabling thermostat controls, leaving fans set to “on,” and opening outdoor air dampers to reduce or eliminate air recirculation inside the building’s air system.

The CDC’s next recommendation, in terms of financial investment, is using fans to bring in fresh air from those open windows or adding portable HEPA air filters to rooms with more traffic. Effective portable filters run from under $100 to several hundred dollars.

As a last resort if options for increasing room ventilation and filtration are limited, the CDC recommends potentially installing ultraviolet germicidal irradiation or blue light systems designed to kill viruses, bacteria, mold, and other problematic things in the air.

Cutler says to assess whether an air purifier is adequate for the space you are planning to purify, look for the Association of Home Appliance Manufacturers verified seal and its clean air delivery rate rating (CADR), which measures the volume of clean air that an air purifier produces on its highest speed setting in cubic feet per minute.

“There are different CADR ratings for removing tobacco smoke, dust, and pollen, but they are generally not rated for removing viral particles,” Cutler said.

Opening windows or adding air purifiers to an indoor space are meant to complement other methods, such as wearing face coverings and physical distancing, not replace them, especially in places such as classrooms or gyms.

However, experts are wary to say one thing is definitely better than the others due to the lack of studies and proof to show how air purifiers deal with the novel coronavirus.

“It is unknown whether opening doors and windows, running fans or any other methods of increasing indoor airflow help prevent COVID-19. But vaccines, masking, and social distancing certainly do,” Cutler said.

While air purifiers have considerations such as cost, portability, and how easy and costly it is to change an air filter, he says getting vaccinated is the best and proven method to make gathering inside much safer.

“If others in your indoor space are not vaccinated, then masking and social distancing are good protection against COVID-19,” Cutler said.