Sewage systems in London vanquished cholera in the 19th century. Pesticides, wide-scale landscape management, and window screens that kept out mosquitos eliminated yellow fever and malaria in the U.S. in the 19th and early 20th centuries. Because SARS-CoV-2 and other respiratory illnesses spread through aerosols, should public health efforts be aimed at transforming indoor ventilation systems?
COVID-19 is unlikely to be the last airborne pandemic, and redesigning the airflow inside buildings could help prevent other respiratory illnesses, such as colds and flu, which have long been accepted as inevitable facts of life.
The World Health Organization did not acknowledge that COVID-19 could spread through the air until July 2020. When scientists initially pushed the organization to recognize airborne transmission, they met resistance. "We want to feel we're in control," explained Catherine Noakes, PhD, who studies indoor air quality at the University of Leeds, in England. "If something is transmitted through your contaminated hands touching your face, you control that. But if something's transmitted through breathing the same air, that is very, very hard for an individual to manage."
In response to the pandemic, some schools and workplaces are requiring open windows, portable HEPA filters, and disinfecting UV lights. But in older, poorly ventilated buildings, these fixes are likely not enough. More detailed studies are required to understand how effectively specific ventilation levels and strategies can reduce disease transmission. These results can inform new indoor air quality standards from the American Society of Heating, Refrigerating, and Air-Conditioning Engineers, which will lead to updated building codes.
"The costs of that kind of large-scale infrastructure remodeling are astronomical, and the tendency is to look for other kinds of fixes," said Nancy Tomes, PhD, a historian of medicine at Stony Brook University.
"While the scale of the changes required is enormous, this is not beyond the capabilities of our society, as has been shown in relation to food and waterborne disease, which have largely been controlled and monitored," Lidia Morawska, PhD, an aerosol scientist at Queensland University of Technology in Australia, and colleagues wrote in a Science editorial.