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Posts Tagged ‘aerosol’

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Covid-19 guidance seems to change every few days. In the beginning, we were very anxious about wiping down every little thing with Clorox. Now we are more worried about the droplets we breathe in and whether the kids’ schools have adequate air circulation.

Performers worry, too, which is why one European orchestra armed itself with facts before bringing in an audience.

Eva Amsen reports at Forbes, “Last week, violinist Daniel Froschauer was in Salzburg with the Vienna Philharmonic, of which he is also the Chairman. The orchestra played at the Salzburg Festival the entire month of August, under strict regulations to ensure that the musicians and their audience are at minimal risk of catching or spreading the SARS-CoV-2 coronavirus. …

The Vienna Philharmonic was one of the first professional orchestras to return to rehearsals and performances since the start of the Covid-19 pandemic, but it wouldn’t have been possible if they hadn’t carried out their own small research study into the way droplets disperse on stage while musicians play. …

“The case of a choir rehearsal in Washington state back in March was a wake-up call for many musical ensembles. The choir thought they were prepared. They didn’t hug, they stood six feet apart throughout their two-and-a-half-hour rehearsal, and they didn’t share food during the break. Despite their precautions, 53 members of the 61-piece choir caught Covid-19, and two died.

“If such a spread could happen at a choir rehearsal, then an orchestra or band rehearsal – particularly one with wind and brass instruments – might pose a similar risk. The virus can be passed on through tiny airborne droplets called aerosols from an infected individual’s mouth or nose. …

“Until a few months ago, we knew very little about how wind instruments spread droplets. It was only since the Covid-19 pandemic that orchestras and other ensembles suddenly needed to understand exactly how singing or playing instruments could spread the virus so that they could mitigate the risk. …

“The Vienna Philharmonic enlisted the help of physician Fritz Sterz. Initially, Sterz and Froschauer hoped that the Vienna Philharmonic members were immune already. The orchestra had passed through Wuhan on a tour of Asia in late 2019, perhaps already encountering the virus there. But this didn’t seem to be the case: Only one member of the orchestra tested positive in an antibody test.

“The next step was to figure out how rehearsals were putting them at risk, by determining how aerosols were formed around their instruments. …

“Sterz and the orchestra found a creative way to visualise the aerosols’ movement. Each musician was placed in front of a dark background and wore a device up their nose to produce aerosols as they breathed.

While playing their instruments, the musicians dispersed the droplets, and a photographer captured images of the cloud of aerosols surrounding each musician.

“By measuring the dispersal of the droplets for each instrument, Sterz was able to get a sense of which musicians created the largest air flow around them. Unsurprisingly, it was the wind musicians. …

“In lieu of the traditional peer review process that follows most scientific studies, the Vienna Philharmonic worked with a notary to verify that they carried out the procedures as they said they did, and that the results were what they measured. It wasn’t the way research is usually done, but it was enough to convince the Austrian government.

“In May, Froschauer got a call from the Austrian Prime Minister. The Vienna Philharmonic was allowed to rehearse, record and perform again, albeit under very strict conditions. To make it work, the musicians are regularly tested, stay a safe distance apart on stage, wear masks when they have to be near each other in the hallways, and limit the size of the audience. …

“In the United States, the National Federation of State High School Associations and the College Band Directors National Association funded the Performing Arts Aerosol Study to determine the best recommendations for school bands, orchestras and other performing arts groups returning to practice this fall term.

Shelly Miller, professor of environmental engineering at the University of Colorado Boulder, is one of the lead researchers on the study. She explains, … ‘Once we knew what the flow looked like, we probed those flows to measure the particles in the flow.’ …

“From the preliminary results, the Performing Arts Aerosol Study concluded that certain safety precautions needed to be put in place before bands and school orchestras could return to rehearsals.

“It’s worth noting here that these various studies into the spread of aerosols between musicians nicely illustrate how the pandemic has changed the pace of scientific research. Normally, research is slow and the process of verifying, publishing and reviewing the work can be slower than the studies itself. But everything was different this summer. Music groups needed advice about returning to rehearsals and pushed for the research to be carried out, soon. …

“ ‘It’s really intense,’ says Miller.” More at Forbes, here.

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00well-marr-jumbo

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.

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