By Stacy Morford, The Conversation
Scientists have been warning for months that the coronavirus could spread through aerosols – tiny breath droplets that people give off when they talk or sneeze and that can linger in the air.
The Centers for Disease Control and Prevention apparently recognized this risk on September 18. Guidelines have been published on their website listing aerosols among the ways the virus could spread, and there has been increasing evidence that particles can remain suspended in the air and move beyond 6 feet. But three days later these instructions were gone. A notice in its place said that a draft had been released in error and that the CDC was still working on the update.
This type of government shift can be confusing. In the following five articles recently published in The Conversation, we reached out to scientists to explain what aerosols are, how airborne particles can carry the coronavirus, and how to protect yourself.
1. What you need to know about aerosols
When you speak or sing, the flow of air breaks up strands of mucus in your airways and sends droplets of it into the air.
While larger droplets fall quickly, tiny, light ones can linger in the air. If you are infected, these droplets can contain the coronavirus, and early research suggests it can be viable for many minutes to hours.
Aerosol experts Byron Erath, Andrea Ferro and Goodarz Ahmadi from Clarkson University discussed the mechanics of aerosols in a recent article for The Conversation.
They also discussed what people can do to protect themselves. “Wearing face-covering to reduce the risk of airborne exposure is critical,” they write. “Reducing the time you spend in poorly ventilated, crowded areas is a great way to reduce the risk of airborne exposure.”
2. Is it enough to stay 6 feet apart?
The usual advice for social distancing is to stay 6 feet apart. It’s easy to remember but doesn’t take into account all aerosol risks – especially indoors.
Since people infected with SARS-CoV-2 can transmit large amounts of the virus, there is no safe distance in a poorly ventilated room, wrote Erath, Ferro, Ahmadi and their colleague at Clarkson University, Suresh Dhaniyala, in a second article. Air currents from a fan or ventilation system can spread breath droplets further than 6 feet. So you can speak or sing loudly, as superspreader events have shown.
The scientists used a smoke room analogy to illustrate the risk and suggested ways to deal with it.
“Over time, it doesn’t matter where you are in space,” they wrote, droplets circulating in the air. “
3. Particles and super spreaders in the air
A large number of COVID-19 cases have been traced back to “superspreader” events, in which someone who is highly contagious spreads the virus to dozens of others.
Researchers in Hong Kong recently estimated that around 20% of those infected there were responsible for 80% of local coronavirus transmission. Choir practice, church services, nightclubs, and a birthday party are just a few of the documented Superspreader events.
Elizabeth McGraw, director of the Center for Infectious Disease Dynamics at Pennsylvania State University, explained the evidence and importance of superspreader events in the transmission of the virus in another article.
“The good news is that the right control practices that are specific to pathogen transmission – hand washing, masks, quarantine, vaccination, reducing social contacts, etc. – can slow the rate of transmission and stop a pandemic,” she wrote.
5. The problem with school buses
As the temperatures get cooler it will be harder to keep the windows open to bring fresh air into enclosed spaces. This includes public transport and school buses.
Jesse Capecelatro, a mechanical engineer at the University of Michigan, has broken down the risks of spreading the coronavirus on a school bus and made eight recommendations.
“Short trips. Masks for everyone. Far fewer passengers than before,” he wrote. “These are my top recommendations on how America’s school buses should get children to and from school during the pandemic.”
Editor’s Note: This story is a round-up of articles from The Conversation archives.
Stacy Morford, General Assignments Editor, The Conversation
This article is republished by The Conversation under a Creative Commons license. Read the original article.