(CNN)Americans are abandoning their masks. They're done with physical distancing. And, let's face it, some people are just never going to get vaccinated.
Yet a lot can still be done to prevent covid infections and curb the pandemic.
A growing coalition of epidemiologists and aerosol scientists say that improved ventilation could be a powerful tool against the coronavirus — if businesses are willing to invest the money.
"The science is airtight," said Joseph Allen, director of the Healthy Buildings program at Harvard University's T.H. Chan School of Public Health. "The evidence is overwhelming."
Although scientists have known for years that good ventilation can reduce the spread of respiratory diseases such as influenza and measles, the notion of improved ventilation as a front-line weapon in stemming the spread of covid-19 received little attention until March. That's when the White House launched a voluntary initiative encouraging schools and work sites to assess and improve their ventilation.
The federal American Rescue Plan Act provides $122 billion for ventilation inspections and upgrades in schools, as well as $350 billion to state and local governments for a range of community-level pandemic recovery efforts, including ventilation and filtration. The White House is also encouraging private employers to voluntarily improve their indoor air quality and has provided guidelines on best practices.
The White House initiative comes as many employees are returning to the office after two years of remote work and while the highly contagious BA.2 omicron subvariant gains ground. If broadly embraced, experts say, the attention to indoor air quality will provide gains against covid and beyond, quelling the spread of other diseases and cutting incidents of asthma and allergy attacks.
The pandemic has revealed the dangerous consequences of poor ventilation, as well as the potential for improvement. Dutch researchers, for example, linked a 2020 covid outbreak at a nursing home to inadequate ventilation. A choir rehearsal in Skagit Valley, Washington, early in the pandemic became a superspreader event after a sick person infected 52 of the 60 other singers.
Ventilation upgrades have been associated with lower infection rates in Georgia elementary schools, among other sites. A simulation by the Centers for Disease Control and Prevention found that combining mask-wearing and the use of portable air cleaners with high-efficiency particulate air filters, or HEPA filters, could reduce coronavirus transmission by 90%.
Scientists stress that ventilation should be viewed as one strategy in a three-pronged assault on covid, along with vaccination, which provides the best protection against infection, and high-quality, well-fitted masks, which can reduce a person's exposure to viral particles by 95%. Improved airflow provides an additional layer of protection — and can be a vital tool for people who have not been fully vaccinated, people with weakened immune systems, and children too young to be immunized.
One of the most effective ways to curb disease transmission indoors is to swap out most of the air in a room — replacing the stale, potentially germy air with fresh air from outside or running it through high-efficiency filters — as often as possible. Without that exchange, "if you have someone in the room who's sick, the viral particles are going to build up," said Linsey Marr, a professor of civil and environmental engineering at Virginia Tech.
Exchanging the air five times an hour cuts the risk of coronavirus transmission in half, according to research cited by the White House Office of Science and Technology Policy. Yet most buildings today exchange the air only once or twice an hour.
That's partly because industry ventilation standards, written by a professional group called the American Society of Heating, Refrigerating and Air-Conditioning Engineers, or ASHRAE, are voluntary. Ventilation standards have generally been written to limit odors and dust,