The plan to stop every respiratory virus at once

Earlier this year, Morawska and dozens of her colleagues in the fields of building science, public health, and medicine published an editorial in Science calling for a “paradigm shift” around indoor air. Yes, vaccines and masks work against the coronavirus, but these scientists wanted to think bigger and more ambitious—beyond what any single person can do to protect themselves. If buildings are allowing respiratory viruses to spread by air, we should be able to redesign buildings to prevent that. We just have to reimagine how air flows through all the places we work, learn, play, and breathe.

The pandemic has already prompted, in some schools and workplaces, ad hoc fixes for indoor air: portable HEPA filters, disinfecting UV lights, and even just open windows. But these quick fixes amount to a “Band-Aid” in poorly designed or functioning buildings, says William Bahnfleth, an architectural engineer at Penn State University who is also a co-author of the Science editorial. (Tellier, Noakes, and Milton are authors too; the author list is a real who’s who of the field.) Modern buildings have sophisticated ventilation systems to keep their temperatures comfortable and their smells pleasant—why not use these systems to keep indoor air free of viruses too?

Indeed, hospitals and laboratories already have HVAC systems designed to minimize the spread of pathogens. No one I spoke with thought an average school or office building has to be as tightly controlled as a biocontainment facility, but if not, then we need a new and different set of minimum standards. A rule of thumb, Noakes suggested, is at least four to six complete air changes an hour in a room, depending on its size and occupancy. But we also need more detailed studies to understand how specific ventilation levels and strategies will actually reduce disease transmission among people. This research can then guide new indoor air-quality standards from the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), which are commonly the basis of local building codes. Changing the building codes, Bahnfleth said, is what will actually get buildings to change their ventilation systems.