Clean water in 1842, food safety in 1906, ban on leaded paints in 1971. These sweeping public health reforms have changed not only our environment but also expectations of what governments can do.

According to a group of 39 scientists, now is the time to do the same for indoor air quality. In a sort of manifesto published Thursday in Science magazine, researchers called for a “paradigm shift” in the way citizens and government officials think about the quality of the air we breathe indoors.

The timing of the scientists’ call to action coincides with the large-scale reopening of the country as coronavirus cases drop sharply: Americans are about to return to offices, schools, restaurants, and theaters – exactly the kind of crowded indoor spaces that the coronavirus is thought to thrive.

There is little doubt that the coronavirus can linger in the air indoors and soar well beyond the recommended six-foot distance, the experts said. The accumulated research places policymakers and civil engineers under an obligation to provide clean air in public buildings and to minimize the risk of respiratory infections.

“We expect clean water from the taps,” said Lidia Morawska, group leader and aerosol physicist at the Queensland University of Technology in Australia. “We expect clean and safe food when we buy it in the supermarket. We should also expect clean air in our buildings and in all common spaces. “

Fulfilling the group’s recommendations would require new workplace air quality standards, but the scientists claimed that remedial action needn’t be onerous. Indoor air quality can be improved with a few simple fixes: adding filters to existing ventilation systems, using portable air purifiers and ultraviolet lights – or just opening windows where possible.

Dr. Morawska led a group of 239 scientists who last year called on the World Health Organization to recognize that the coronavirus can spread in tiny droplets, or aerosols, that drift through the air. WHO had insisted that the virus only spread in larger, heavier droplets and by touching contaminated surfaces, which went against their own 2014 rule of assuming that all new viruses are in the air.

The WHO admitted on July 9th that aerosol transmission of the virus could be responsible for “Covid-19 outbreaks that have been reported in some closed settings, such as in a public house. For example, in restaurants, night clubs, places of worship or workplaces where people may shout, speak or sing ”, but only at a short distance.

The pressure to take measures to prevent airborne spread has increased recently. In February, more than a dozen experts requested the Biden administration to update workplace standards for high-risk environments such as meat packers and prisons where Covid outbreaks were widespread.

Last month, a separate group of scientists detailed 10 lines of evidence demonstrating the importance of indoor air transmission.

On April 30, the WHO pushed forward and allowed aerosols to “float in the air or move more than 1 meter (long range)” in poorly ventilated rooms. The Centers for Disease Control and Prevention, which were also slow to update their guidelines, realized last week that the virus can be breathed indoors, even if a person is more than three feet from an infected person.

“You have ended up in a much better, more scientifically feasible place,” said Linsey Marr, Virginia Tech airborne virus expert and signatory of the letter.


May 17, 2021 at 1:32 p.m. ET

“It would be helpful if they ran a public service messaging campaign to promote this change more widely,” she said, especially in parts of the world where the virus is soaring. For example, in some East Asian countries, stacked toilet systems could transport the virus between the floors of a multi-story building, she noted.

Further research is also needed to determine how the virus moves indoors. Researchers at the Department of Energy’s Pacific Northwest National Laboratory modeled the flow of aerosol-sized particles after a person in a three-room office with a central ventilation system had a five-minute coughing fit. Clean outside air and air filters reduce the flow of particles in this room, the scientists reported in April.

A rapid exchange of air – more than 12 in an hour – can move particles into connected rooms, just as second-hand smoke can pour into lower levels or nearby rooms.

“A lot more ventilation is a good thing for the source room,” said Leonard Pease, chemical engineer and lead author of the study. “But this air goes somewhere. Perhaps more ventilation is not always the solution. “

In the United States, the CDC’s license can cause the Occupational Safety and Health Agency to change its air quality regulations. Air is harder to hold and clean than food or water. However, OSHA already prescribes air quality standards for certain chemicals. The guide for Covid does not require ventilation improvement except in healthcare.

“Ventilation is really part of the approach OSHA takes to all airborne hazards,” said Peg Seminario, who served as the AFL-CIO’s director of safety and health at work from 1990 until her retirement in 2019 these approaches should apply to the air. “

In January, President Biden instructed OSHA to issue temporary emergency guidelines for Covid by March 15. OSHA missed the deadline, however: the draft is reportedly under review by the White House regulator.

In the meantime, companies can do as much or as little as they want to protect their workers. Citing concerns about the continuing shortage of protective equipment, the American Hospital Association, an industry trade group, endorsed N95 respirators for healthcare workers only during medical procedures known to produce aerosols or when in close contact with an infected person Patients have. These are the same guidelines that the WHO and CDC offered at the start of the pandemic. Face masks and plexiglass barriers would protect the rest, the association said in a March statement to the House Committee on Education and Labor.

“They are still stuck in the old paradigm, they have not accepted the fact that speaking and coughing often produce more aerosols than these so-called aerosol producing processes,” said Dr. Marr from the hospital group.

“We know plexiglass barriers don’t work,” she said and can actually increase the risk, possibly because they obstruct proper airflow in a room.

The improvements don’t have to be expensive: in-room air filters cost less than 50 cents per square foot, although a lack 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 for Heating, Cooling and Air Conditioning Engineers), which sets standards for such devices. UV light built into a building’s ventilation system can cost up to $ 1 per square foot. Those that are installed room-by-room perform better, but could cost ten times as much, he said.

If OSHA rules change, demand could lead to innovation and lower prices. There are precedents to believe that this could happen, according to David Michaels, a professor at George Washington University who served as OSHA director under President Barack Obama.

When OSHA tried to control exposure to a carcinogen called vinyl chloride, which is the building block of vinyl, the plastics industry warned about it threatening 2.1 million jobs. In fact, within a few months, companies have “actually saved money and not a single job has been lost,” recalls Dr. Michaels.

In either case, absentee workers and healthcare costs can prove more costly than ventilation system updates, the experts said. Better ventilation helps thwart not only the coronavirus but other respiratory viruses that cause influenza and colds, as well as pollutants.

Before people realized the importance of clean water, cholera and other water-borne pathogens claimed millions of lives worldwide each year.

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