Staying Safe from COVID-19: It’s All About the Aerosols
The progression of COVID-19 in the U.S. continues its grim march. At least 190,000 Americans died in the eight months since its initial appearance here, with as many as 410,00 total deaths projected by the end of the year. This projection comes from the Institute for Health Metrics and Evaluation (IHME). These experts’ projections are most often cited by the White House Coronavirus Task Force.
Their researchers also advised this figure could be reduced by as much as 30 percent if more of us would wear face coverings, a practice they noted is declining. Our family practice doctors are sobered by these numbers, and we want to ensure Floridians are staying safe from COVID-19. Here we provide the latest findings on halting the spread of SARS-CoV-2, the virus that causes COVID-19.
What we’ve learned
After a few false starts early on, we’ve learned an amazing amount about this new coronavirus, including more reliable data about how it spreads.
Preliminary evidence showed at least some of the reason why COVID-19 is so contagious. Now we’ve learned more that seems to support the theory that airborne transmission as a significant—if not primary—mode.
Late last month, a report from researchers at the Massachusetts Institute of Technology (MIT) and the University of Oxford suggested the six-foot distancing we’ve observed for months may not provide enough of a safety factor. Transmission is actually dependent on a variety of situations. These researchers created a color-coded chart to show the various levels of risk of contracting COVID-19 attached to different situations.
“People have put too much weight on six feet as being this dividing line between risky and safe,” Linsey Marr, a professor of civil and environmental engineering at Virginia Tech, told NBC News. “And this [study] clearly shows we’ve known that six feet is a guideline but that the farther the better.” Marr, who studies airborne transmission, was not part of the MIT/Oxford study.
Mitigating or exacerbating factors include air circulation, crowd density, ventilation and length of exposure. Whether people are wearing face masks, and whether they are speaking, shouting, singing, coughing or not speaking at all factor in when considering safety.
Scientists are learning this particular virus is not transmitted solely by relatively large droplets that leave our noses and mouths when we breathe. These particles may often be accompanied by microscopic airborne particles called aerosols that can linger in the air for many minutes, possibly even hours. Think of cigarette smoke or heavy perfume: not only how long these odors linger in the air but how far they can spread.
“Distance alone will never solve the aerosol problem. If you are in the same room, you can get infected,” University of Colorado aerosol expert Jose-Luis Jimenez told The Washington Post. “Outdoors, distanced, and with well-fitted masks is the only thing close to a silver bullet.”
Official resistance vs. emerging evidence
Although many health organizations, both in the U.S. and worldwide, still hesitate to definitively state that aerosols are a primary method of transmission of the SARS-CoV-2 virus, a group of more than 200 scientists wrote an open letter to the World Health Organization (WHO) in July citing “emerging evidence” of airborne transmission and urging the organization to acknowledge the role aerosols can play.
For example, one air sampling study found in the hallways near the rooms of patients infected with COVID-19 at the University of Nebraska Medical Center contained enough residual live virus that researchers were able to grow the pathogen in cell cultures just from the lingering aerosols. Another study found living viral particles up to 16 feet away from COVID-19 patients at a hospital in Gainesville, FL.
Staying safe from COVID-19
Dr. Ezekiel Emanuel, a bioethicist and oncologist who is vice provost for global initiatives at the University of Pennsylvania, explained that the levels of risk boils down to four factors:
- whether you are indoors or outdoors
- how many people you’re in contact with
- how long you’re in contact with them
- whether heavy breathing, such as shouting or singing, is involved
“If you’re outdoors, not in a crowd, and not going to be with other people for prolonged periods of time, that’s probably good,” Emanuel, who was not involved in the MIT/Oxford study, told NBC News. “Is it a zero-risk scenario? Nothing’s zero-risk.”
Our best advice? Assume every other person you meet, unless you live closely with them, is infected and can infect you.
Although initial advice regarding masks indicated the practice wouldn’t protect the wearer, only others they come in contact with, more recent research shows that it does offer some measure of protection for the wearer as well.
Stay as far away from others as possible, especially in crowded and/or indoor settings, and wear a mask over your mouth and nose. Also, avoid touching your face until you’ve washed your hands.
As Marr told The Post, “Infected people, whether they have symptoms or not, are releasing virus into the air. And you can get it by breathing that in.”