"After urging steps like handwashing, masking and social distancing, researchers say proper ventilation indoors should join the list of necessary measures. Health scientists and mechanical engineers have started issuing recommendations to schools and businesses that wish to reopen for how often indoor air needs to be replaced, as well as guidelines for the fans, filters and other equipment needed to meet the goals.
"We didn't focus on it enough initially," said Abraar Karan, a doctor at Brigham and Women's Hospital in Boston who treated Covid-19 patients. "We told everyone to stay home. We weren't thinking about people congregating in public spaces."
Driving the thinking is mounting evidence that the new coronavirus is transmitted through the air among people with prolonged exposure to the pathogen. Especially troublesome, epidemiologists and other scientists say, is evidence from numerous indoor outbreaks suggesting the virus's ability to spread to others even when close contact is avoided.
The precise role that airborne transmission plays is still being debated by parts of the scientific community. Yet proponents of aerosol transmission say the evidence so far argues for the need to keep clean air flowing in indoor spaces where people gather.
Ideally, they say, public spaces like a standard classroom should aim to have air replaced with clean air between four to six times an hour to dilute Covid-19 particles that might accumulate.
That can be done, aerosol scientists and building engineers say, through strategies that introduce outdoor air and filter indoor contaminants. Those include opening windows and doors, installing window fans, using portable air purifiers with high-efficiency particulate air filters, and upgrading heating, ventilation and air-conditioning systems to meet certain standards.
Some businesses have begun taking such steps, including malls and gyms in New York, where reopening guidelines list enhanced air filtration as mandatory for the spaces. But in aging schools nationwide, strengthening ventilation may be difficult.
About 41% of U.S. public-school districts need to update or replace their HVAC systems in at least half their schools, representing about 36,000 schools nationwide, according to a report published in June by the U.S. Government Accountability Office, a federal watchdog. Repairs can be costly. Denver Public Schools said it plans to spend nearly $5 million before students return to improve HVAC systems across roughly 185 buildings.
Scientists argue a significant role is played by smaller particles invisible to the naked eye, called aerosols, that linger in the air and travel. A recent study -- which found that particles extracted almost 16 feet from hospitalized Covid-19 patients could infect cells in a lab -- suggests aerosols as a potential source of spread, aerosol scientists say. The study, posted on the preprint server medRxiv, hasn't been peer reviewed.
"Based on the evidence we have on hand, it seems wildly irresponsible to me not to recommend strategies" for ensuring strong ventilation, said Joseph Allen, director of Harvard University's Healthy Buildings program.
A coronavirus outbreak at a choir rehearsal in Washington state was likely exacerbated by poor ventilation, a study showed. Some 53 of 61 attendees were confirmed or strongly suspected to have Covid-19, including two who died.
Doors were closed at the church's fellowship hall where the March rehearsal took place, the study, published on a preprint server in June, found. One of the authors said the research team believes that a furnace wasn't likely operating for most of the rehearsal, providing no filtration or outdoor air supply through the system when it was off." [1]
Infectious coronavirus particles are found within five meters of the patients. In Lithuania, it is only a question of maintaining a distance of one meter between people, it is never a question of ventilation. Why are we still lagging behind in such a matter of life and death? If someone smokes in the room, and you feel the smell while away, it means coronavirus aerosols can also come up to you. It means ventilation is messy, complain about your employer to the authorities and go home. Let Veryga work there instead of you.
1. McCabe, Caitlin. Wall Street Journal, Eastern edition; New York, N.Y. [New York, N.Y]02 Sep 2020: A.6.
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