As society tries to rebound from the coronavirus pandemic, some scientists hope a decades-old technology could zap pathogens out of the air in stores, restaurants and classrooms, potentially playing a key role in containing further spread of the infection.

It has the ungainly name of upper-room ultraviolet germicidal irradiation, and it is something like bringing the power of sunlight indoors.

“We have struggled in the past to see this highly effective, very safe technology fully implemented for airborne infections,” said Dr. Edward A. Nardell, a professor of global health and social medicine at Harvard Medical School. “We’ve done the studies. We know it works.”

Sunlight disinfects, and the UV part of its spectrum is particularly effective at knocking out airborne pathogens.

This is not what President Trump incomprehensibly described in April when he suggested irradiating the insides of Covid-19 patients with ultraviolet light. Portable ultraviolet units are already being used to sterilize surfaces in hospital rooms and subway cars, but these can be used only when those spaces are unoccupied.

In the approach scientists like Dr. Nardell describe, fixtures mounted on walls or ceilings, similar to fluorescent lights used today, shine ultraviolet light across the top of an interior space, well above people’s heads. Ceiling fans are sometimes installed to draw air upward so that floating bacteria, viruses and fungi are zapped more quickly. A different frequency of ultraviolet might be even safer, even when it shines directly on people, which would also allow disinfection of surfaces.

Ultraviolet light mangles the genetic material in pathogens — DNA in bacteria and fungi, RNA in viruses — preventing them from reproducing. “You’ve killed it essentially,” said William P. Bahnfleth, a professor of architectural engineering at Pennsylvania State University.

ImageFour ultraviolet fixtures, placed in the corners of a room with a ceiling fan to draw air upward, could effectively remove floating bacteria, viruses and fungi.
Credit…University of Maryland

Dr. Nardell estimated that installing commercially available fixtures for an intermediate-size warehouse-type store like Walmart would cost about $100,000, which might be too expensive for some smaller businesses.