Is Coronavirus Airborne?

New research suggests that Covid-19 droplets can linger in the air

Hospital personnel registers patients brought by ambulances for the coronavirus tests at Ankara City Hospital on April 18, 2020, in Ankara, Turkey. Photo: Aytug Can Sencar/Anadolu Agency/Getty Images

As people everywhere scramble to keep a safe distance from one another (or not), scientists are hard at work trying to figure out whether the coronavirus is airborne. While they agree that coughing, sneezing, talking, and breathing can expel tiny droplets of moisture that can contain the virus, it isn’t quite clear how long those droplets hang in the air.

Today in the journal Nature, however, researchers from Wuhan, China, offer a bit of clarity. In their small study of the air in two Wuhan hospitals and some public areas, they found that fragments of the virus can indeed stay airborne in droplets — in some places more than others. Specifically, they found particles of viral RNA (the genetic material of the virus) in these droplets. Notably, there’s no evidence yet that these viral RNA particles can cause a Covid-19 infection.

Between February 17 and March 2, they collected 30 samples by setting up “aerosol traps” — gelatin filters for catching tiny particles in the air — in specific areas of two Wuhan hospitals, including patient wards, patient toilets, and the rooms where staff take off protective equipment. They also sampled the air in public zones in Wuhan, like the areas outside grocery stores, residential buildings, pharmacies, and hospitals.

Using a technique for amplifying genetic material from even the most minute samples, the researchers identified the types of areas that had the highest levels of viral RNA. Ventilation appears to play a big role, the paper suggests: Ventilated patient isolation wards and rooms had “very low” levels, but levels in patients’ toilet areas, which weren’t ventilated, were “elevated.”

The rooms where hospital staff removed their protective gear also had high concentrations of viral RNA, the authors write, but these dropped to “undetectable levels” after the hospitals started more rigorous sanitization. This suggests that, although viral RNA on their equipment can be resuspended in the air, thorough cleaning effectively gets rid of it.

All but two of the public areas they tested had “undetectable” levels of viral RNA. The two exceptions were two areas that were prone to crowding: a site about three feet from…