Diners walking into a restaurant might be able to tell a lot about how the establishment is mitigating the risk of spreading the novel coronavirus. They can see the servers in masks, the touchless systems many are offering for payment, the frequent disinfection by staff of commonly touched surfaces.

But there’s one thing they can’t see, according to The Washington Post, that could play a part: The air around them. 

For months, public health experts have described the virus as being primarily transmitted through droplets from an infected person’s cough or sneeze to nearby people or surfaces.

Lately, research and discussion has focused on airborne transmission over longer distances. Some scientists say COVID-19 can spread by traveling in small particles called aerosols.

“That evidence is building right now,” says Chad Roy, director of infectious-disease aerobiology at the Tulane National Primate Research Center. “It’s not as prominent a pathway [as droplets or infected surfaces], but it’s one we need to pay attention to.”

How the virus is transmitted might be more important in restaurants than in many other venues, notes L. James Lo, an assistant professor at Drexel University in Philadelphia who studies airflow and how viruses circulate, because people linger there far longer than they do in, say, a grocery store. Exposure to the virus can come from encountering a high dose for a short time or a low dose over a longer period, he says. 

Public health experts are recommending alfresco activities, including dining, over indoor ones. The virus is quickly diluted in fresh air, Roy notes. 

When it comes to indoor situations, two functions of air-conditioning systems can help prevent the spread of a virus: Ventilation—fresh air coming into the building from outside—and filtration, or removing small particles from the air. 

A good gauge is that it feels stuffy indoors, it might be better to sit outside, Roy says. Read the full story.