Air Filters Don't Stop You Getting Sick, Microbiologists Say

If you've been relying on air filtration systems to protect yourself from viruses like SARS-CoV-2, you might want to think again. In March 2022, the U.S. Environmental Protection Agency released its Clean Air in Buildings Challenge, a set of guidelines for building owners and operators to reduce the risks posed by airborne viruses in indoor settings. As part of its recommendations, the government encouraged the installation of air filtration and cleaning systems as well as UV Germicidal Irradiation systems. However, a new study from the University of East Anglia in the U.K. suggests that these measures may not have had much impact on our risk of viral infection. "During the pandemic, all sorts of things were tried and recommended to try to limit transmission and harms," study lead Julii Brainard told Newsweek. "Some of these ideas were very expensive. "Aside from pointless expense, if a strategy is widely advocated and adopted that isn't effective, that fact itself can undermine public trust. It's important that we use actual evidence about what is effective or not, when deciding what public health measures to take, whenever possible."

When it comes to air cleaning technologies, there are two main approaches: "HEPA filters try to physically remove the virus from the air," Brainard said. "Other technologies like germicidal UV light try to disable the virus, so it's still in the air but can't infect and can't replicate itself—viruses are just bundles of genetic code anyway, very small and not much else to them." In their recent study, published in the journal Preventive Medicine on November 17, Brainard and her team analyzed 32 studies looking into the efficacy of these air cleaners. These studies were all conducted in real-world environments like schools and care homes. "Our findings are disappointing," Brainard said. "But it is vital that public health decision makers have a full picture." In their analysis, Brainard and her team did not find any evidence to suggest that these air cleaners significantly reduced the risk of airborne infections. However, they did add that none of the studies of air treatment methods started during the COVID era has yet been published. "Hopefully those studies that have been done during COVID will be published soon and we can make a more informed judgment about what the value of air treatment may have been during the pandemic," Brainard said.

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However, for now, Brainard is not overly optimistic about the development of more effective air cleaners in the future. "I have doubts because viruses are incredibly small and numerous, and how people interact can be so intimate and immediate," Brainard said. "However, I'm not an engineer and humans have achieved great technological things. My best guess is that the odds are that these air treatment technologies will become more effective over time than they are now, at safely preventing infections." For the time being, if you want to protect yourself and your family from infections, Brainard said there is a much more effective method: "Vaccination is incredibly effective against most of the dangerous infections. You could avoid people forever in absence of vaccination, but that would be very counterproductive to obtaining and maintaining good health [...] The risk balance is a personal decision."