only during medical procedures known to produce aerosols, or if they have close contact with an infected patient. Those are the same guidelines the W.H.O. and the C.D.C. offered early in the pandemic. Face masks and plexiglass barriers would protect the rest, the association said in March in a statement to the House Committee on Education and Labor.

“They’re still stuck in the old paradigm, they have not accepted the fact that talking and coughing often generate more aerosols than do these so-called aerosol-generating procedures,” Dr. Marr said of the hospital group.

increase the risk, perhaps because they inhibit proper airflow in a room.

The improvements do not have to be expensive: In-room air filters are reasonably priced at less than 50 cents per square foot, although a shortage of supply has raised prices, said William Bahnfleth, professor of architectural engineering at Penn State University, and head of the Epidemic Task Force at Ashrae (the American Society of Heating, Refrigerating and Air-Conditioning Engineers), which sets standards for such devices. UV lights that are incorporated into a building’s ventilation system can cost up to roughly $1 per square foot; those installed room by room perform better but could be 10 times as expensive, he said.

If OSHA rules do change, demand could inspire innovation and slash prices. There is precedent to believe that may happen, according to David Michaels, a professor at George Washington University who served as OSHA director under President Barack Obama.

When OSHA moved to control exposure to a carcinogen called vinyl chloride, the building block of vinyl, the plastics industry warned it would threaten 2.1 million jobs. In fact, within months, companies “actually saved money and not a single job was lost,” Dr. Michaels recalled.

In any case, absent employees and health care costs can prove to be more costly than updates to ventilation systems, the experts said. Better ventilation will help thwart not just the coronavirus, but other respiratory viruses that cause influenza and common colds, as well as pollutants.

Before people realized the importance of clean water, cholera and other waterborne pathogens claimed millions of lives worldwide every year.

“We live with colds and flus and just accept them as a way of life,” Dr. Marr said. “Maybe we don’t really have to.”

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