WRAL Investigates

Researchers suggest coronavirus can linger in air for hours

Posted May 29, 2020 3:33 p.m. EDT
Updated May 30, 2020 10:25 a.m. EDT

— As more people venture out during the pandemic, there are still a lot of unknowns about coronavirus, including how it spreads and how contagious it is. Some experts believe the threat is bigger than health officials first recognized.

North Carolina officials have been preaching the "three W's" for weeks – wear a face covering, wait 6 feet away from people and wash your hands – to prevent the spread of the virus, but some researchers say that might not be enough. Outbreaks in congregate settings suggest the virus is spread through aerosol droplets that can linger in the air.

"If you’ve been following advice about COVID-19 from the Centers for Disease Control and Prevention or the World Health Organization, chances are you’ve heard a lot about how the coronavirus can travel through large droplets via coughing and sneezes. You’ve also probably heard abut the virus being transmitted through surfaces. But you probably haven’t heard anything about airborne transmission, which many organizations have largely ignored. That’s a mistake," Dr. Joseph Allen of Harvard University’s T.H. Chan School of Public Health wrote in an opinion piece in The Washington Post.

"Airborne transmission – caused by small particles that can linger in the air for extended periods of time, unlike droplets from coughs, which settle quickly – is key to understanding why this disease spreads so rapidly in certain circumstances. It’s also key to figuring out how to best reopen our country," Allen wrote.

The best way to battle the threat of airborne transmission, he said, is to be SMART: Stay at home, Mask wearing when out, Avoid large gatherings, Refresh indoor air and Ten feet is better that 6.

"The hypothesis that the virus is aerosolized in traveling more than 2 meters is a viable one. We need to further study it," said Dr. Greg Gray, an infectious disease epidemiologist at Duke University.

Gray leads the Duke One Health Network, which involves a team of professionals around the globe studying dozens of pathogens. Gray and his local team are currently studying the spread of coronavirus by collecting samples in rooms of COVID-19 patients.

Based on research, he said he believes aerosol spread is happening, but it’s not responsible for most of the cases.

"I would guess that 10 percent, maybe 15 percent, are acquiring this through aerosol," he said, adding that air flow matters, especially indoors, if the virus is present.

"You don't want to be in a place where the air is stagnant," he said.

One lingering question for researchers is, while the virus may spread through aerosol, how long it remains contagious. Gray says that’s an important factor.

"Sometimes, the particles dry up, and the virus is no longer alive," he said.

Regardless of the findings, Gray says the virus is more contagious than experts initially thought. He encourages people to continue following recommendations of federal, state and local health officials who are making decisions based on science.

Gray wears a mask in public and keeps his distance, but he said people need to find a balance in all of the incomplete data.

"We’re going to have to take some risks. This thing isn’t going away," he said.

A previous version of this story online mistakenly said the coronavirus droplets can linger in air for years. This is incorrect. The story has now been corrected for accuracy. We regret this misprint.

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