Coronavirus disease, caused by the agent of Severe Acute Respiratory Syndrome 2 (SARS-CoV-2) is wreaking havoc around the world, with its second wave occurring in many countries.

With the winter season quickly approaching in the northern hemisphere, more people will stay indoors, which could lead to further spread of the virus. Previous studies have shown that the spread of the virus indoors, especially in offices, grocery stores, concert halls and other places with less ventilation, can intensify as the cold season begins.

At 73rd At the annual meeting of the American Physical Society’s Division and the American Physical Society’s Division of Fluid Dynamics, researchers presented a series of studies examining the aerodynamics of infectious diseases.

The results of one study revealed that the number of micron-scale expiratory particles emitted during vocalization, such as singing or speaking, increases dramatically with volume. The number of viral particles is also markedly increased by coughing.

Simulation of pedestrian counter-current (red and pink particles) confined in a corridor (blue limit), under conditions of low social distancing. CREDIT Kelby Kramer and Gerald J. Wang

How COVID-19 is spread

SARS-CoV-2 is spread primarily by contact and respiratory droplets. In certain circumstances, airborne transmission can occur, for example when aerosol-generating procedures are performed in healthcare facilities, in crowded indoor environments with poor ventilation, and when people talk, breathe or sing.

The U.S. Centers for Disease Control and Prevention (CDC) has updated their guidelines, recognizing that SARS-CoV-2 is spread through aerosols. The World Health Organization (WHO) has also recognized the potential for the coronavirus to spread through aerosols and therefore recommends people avoid closed areas with poor ventilation.

With the potential for airborne transmission, health agencies are reiterating the importance of basic infection protocols to prevent infection, such as wearing masks, physical distancing, and regular hand hygiene.

The virus is spread by singing and talking

Previous research has shown the role of large, rapidly falling objects produced by coughing or sneezing. In some super-spray events, people were infected with SARS-CoV-2 while they were with other people inside. For example, of 61 singers in Washington state, 53 contracted the virus after a 2.5-hour choir rehearsal in March. In another incident, 24 of 67 passengers who were on a bus for two hours were infected with the virus in Zhejiang province in China.

In a reportWilliam Ristenpart, a chemical engineer at UC Davis, revealed that when people speak or sing loudly, they generate more particles the size of a micron than when they use a normal voice.

“Theoretical calculations suggest that vocalizing less often and more silently results in a substantial decrease in the likelihood of transmission,” the report explained. In addition, the report added that the particles produced by shouting or shouting far exceed the number produced by coughing.

In experiments on guinea pigs, the study researchers pointed out that influenza is transmitted via fomite aerosols, which are virus-contaminated dust particles released from the animals’ fur and cages, not their exhalation. The team concluded that these contaminants could be released from sources routinely used by humans, including tissue papers.

“Our results suggest that researchers should broaden their scope beyond coughing and sneezing as a suspected airborne disease transmission mechanism,” the study authors concluded.

Propagation via musical instruments

Another study by researchers at the University of Colorado, Boulder, focused on how the virus could be spread through musical instruments. The team carried out experiments to measure aerosol emissions from musical instruments.

The team said flutes, for example, don’t generate as much aerosol when used. However, instruments such as oboes and clarinets, which have moist, vibrating surfaces, tend to produce a lot of aerosols.

Aerosol emissions from musical instruments can be controlled. When a mask is placed on a trumpet or clarinet bell, it reduces the number of airborne particles to levels in a normal tone of voice.

Meanwhile, a research team from University of Minnesota revealed that although the amount of aerosols produced differed depending on the musician and instrument, they rarely traveled more than a foot. Therefore, the team designed a pandemic-sensitive seating model for live orchestras. They also decided where to place the filters and members of the public to reduce the risk of the virus spreading.

At work

During the pandemic, many employees chose to work from home. As restrictions are relaxed, employers are exploring ways to safely reopen their workplaces while maintaining physical distance between their employees. A team of researchers from Carnegie Mellon University used two-dimensional simulations that modeled people as particles. They identified specific conditions that would help avoid overcrowding in confined spaces such as hallways.

One of the issues employees face amid the global health crisis is commuting to and from office buildings. Since passenger cars also pose a risk of infection, a team of researchers at Brown University calculated how the air moves in the cabs of passenger cars to determine strategies to reduce the risk of the virus spreading. . For example, strategically opening some windows while closing others can help reduce risk.

As the new normal begins to take hold in many countries, identifying ways to reduce the spread of the virus is crucial in tackling the COVID-19 pandemic.

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