Photos from the areas hardest hit by the novel coronavirus SARS-CoV-2 tell a story of disinfection: Trucks spraying streets and a phalanx of sanitation workers wearing backpack tanks fogging sidewalks, parks, and plazas in China, South Korea, Italy, and elsewhere. Countless recommendations admonish us to wash our hands and disinfect often-touched surfaces in our homes. But what is the most effective way to prevent exposure to the virus?
Like other coronaviruses, severe acute respiratory syndrome coronavirus 2, which causes COVID-19, is thought to spread most commonly through invisible respiratory droplets sent into the air when an infected person coughs or sneezes. Those droplets can then be inhaled by nearby people or land on surfaces that others then touch, who can then get infected when they touch their eyes, nose, or mouth.
The good news from investigations of the coronavirus spread, says Juan Leon, an environmental health scientist at Emory University, is that past studies show common household disinfectants, including soap or a diluted bleach solution, can deactivate coronaviruses on indoor surfaces. “Coronaviruses are enveloped viruses with a protective fat layer,” Leon says. Disinfectants tear apart that fat layer, Leon says, which makes coronaviruses “fairly wimpy” compared to noroviruses and other common viruses that have a more robust protein shell.
So, how long does SARS-CoV-2 stick around in the air or on surfaces? That depends. According to a preprint posted, the virus persists in the air for up to 3 hours and for 2 to 3 days on stainless steel and plastic surfaces. In research published in the Journal of Hospital Infection, researchers found that a related coronavirus that causes SARS can persist up to 9 days on nonporous surfaces such as stainless steel or plastic. And according to reports including one published yesterday in JAMA, SARS-CoV-2 has been detected in feces, suggesting the virus could be spread by people who don’t properly wash their hands after using the bathroom. But thus far, the U.S. Centers for Disease Control and Prevention says there is no indication that it spreads through drinking water, swimming pools, or hot tubs.
So, what about outdoors?
According to a variety of local news reports from cities including Shanghai and Gwangju, South Korea, the disinfectant most commonly used outdoors is a diluted solution of sodium hypochlorite, or household bleach.