All over the world, workers are soaping, wiping and fumigating surfaces with an urgent sense of purpose: to fight the coronavirus. But scientists increasingly say that there is little to no evidence that contaminated surfaces can spread the virus. In crowded indoor spaces like airports, they say, the virus that is exhaled by infected people and that lingers in the air is a much greater threat.

Hand washing with soap and water for 20 seconds — or sanitizer in the absence of soap — is still encouraged to stop the virus’s spread. But scrubbing surfaces does little to mitigate the virus threat indoors, experts say, and health officials are being urged to focus instead on improving ventilation and filtration of indoor air.

“In my opinion, a lot of time, energy and money is being wasted on surface disinfection and, more importantly, diverting attention and resources away from preventing airborne transmission,” said Dr. Kevin P. Fennelly, a respiratory infection specialist with the United States National Institutes of Health.