Suzanne's Mom's Blog

Photo: Peter Means.
Linsey Marr’s unusual set of skills puts her in high demand for insight into Covid-19 aerosol dangers.

With new Covid-19 data coming out every day, I am a bit less anxious about potential germs on the groceries and a bit more concerned about how long a contaminated droplet can last in the air and how many droplets it takes to get sick. Even the experts don’t know. But it sure is reassuring to read about people who are on the case. Dr. Linsey Marr, for example.

Tara Parker-Pope wrote about her recently at the New York Times. “When Linsey Marr’s son started attending day care 12 years ago, she noticed that he kept getting sick with the sniffles and other minor illnesses. But unlike most parents, Dr. Marr, an aerosol scientist at Virginia Tech, tried to figure out why. …

“Dr. Marr was uniquely equipped to tackle the problem [of airborne illness]. She had graduated with an engineering science degree from Harvard University, where she developed an interest in air pollution during her daily runs breathing car exhaust on nearby Boston streets.

“She earned a doctorate in civil and environmental engineering from the University of California at Berkeley, and completed post-doctorate work at the Massachusetts Institute of Technology, with Mario J. Molina, a Nobel laureate recognized for research into ozone damage caused by chlorofluorocarbon gases.

“But it was during that first foray into day care germs that she discovered how little was known about airborne transmission of viruses.

‘I was surprised to find out we don’t even know how much of the flu is spread through the air or through touching,’ Dr. Marr said. …

“Now, Dr. Marr’s maternal and scientific curiosity and her multidisciplinary background have made her one of the world’s leading scientists on airborne viruses. Her research led to the publication of a groundbreaking study that found flu virus in microscopic droplets that were small enough to remain floating in the air for an hour or more. …

“Public health officials in the United States and with the World Health Organization have called on Dr. Marr for her expertise, and scientists from all over the world have asked her to review their papers. Her lab has focused on testing new materials to solve shortages of personal protective equipment for medical workers. Working with her colleagues and graduate students, Dr. Marr’s lab found that a large stockpile of expired respirator masks were still effective but that 3-D printed masks unfortunately were not.

“ ‘There are not many people who are trained engineers who also study infectious disease,’ said Dr. X.J. Meng, a Virginia Tech professor who studies emerging animal viruses. … ‘Linsey is one of very few scientists who has this ability to study aerosol transmission because she can use the engineering tools to study the dynamics of viruses and bacteria in the air.’ …

“Part of the reason Dr. Marr has become so popular in public forums is her ability to explain difficult scientific concepts in easy-to-understand terms. She uses the visual of cigarette smoke when explaining viral plumes. To explain a concept called Brownian motion — and why masks can more easily filter the smallest microscopic particles — she uses the analogy of a drunken person stumbling into chairs and walls while trying to cross a room. ‘The particle is the drunk person, and the chairs are the fibers of the masks,’ she says. ‘The fibers stop the particles.’

“When people began asking whether their clothes could be covered in virus after going to the store or walking outdoors, she gave us all a lesson in aerodynamics.

Just as bugs don’t smash into the windshield of a slow-moving car because they’re carried by air currents alongside the car, lingering viral particles also slip by the human body as we move, and don’t smash into our clothes, she explained. …

“She used mathematical models to determine the safety of hugging during a viral outbreak, taking photos with her daughter in various hug positions to explain how to lower risk. She collaborated with Dutch researchers on how we can safely return to the gym. And her team is in the midst of research on the benefits of homemade masks.

“But the demand for Dr. Marr’s expertise also highlights an alarming problem in the study of viruses and respiratory illness. There are, perhaps, fewer than a dozen scientists around the world with extensive expertise in aerosol transmission of viruses, but funding for their research often falls between the cracks of different disciplines. Basic science grants tend to view airborne viruses as a topic to be supported by health funds. But health agencies tend to focus on how a virus behaves inside the body, not how it gets there. Environmental scientists may study waterborne pathogens or air pollution, but they don’t typically focus on airborne transmission of disease. …

“Despite knowing more than most of us about the risks posed by the coronavirus, Dr. Marr exudes a sense of calm about managing risks. She has access to top-rated N95 medical masks, but she chooses to wear a cloth mask, like the rest of us. … ‘For the things we don’t know, it’s good to err on the safe side, but also to not be paranoid.’

“Dr. Marr said she personally focuses on a ‘top four’ for lowering risk — social distancing, avoiding crowds, wearing a mask and washing hands.”

More at the New York Times, here.