Small coronavirus respiratory particles stay in the air longer and can travel longer distances than previously thought, according to a study conducted in a laboratory. Scientists at the US Department of Energy Pacific Northwest National Laboratory estimate that drops bound in saliva can stay moist for up to 30 minutes and travel up to about 200 feet.Also read – Chandigarh changes office hours from February 21 to reduce traffic congestion. Check out the latest times here
“There are reports of people becoming infected with the coronavirus within minutes of an infected person leaving the room or an infected person leaving that room,” said Leonard Pease, co-author of the study. Also read – Taj Mahotsav 2022: Date, place, ticket price and everything you need to know
“The idea that envelope vision can be well hydrated and thus fully infected at significant distances is consistent with real-world observations. Perhaps the drops of infectious respiration last longer than we understand,” Pace added. Also read – ‘We can overshoot runways’: WHO warns countries to lift COVID-19 restrictions in a hurry
The findings were published in the journal International Communications in Heat and Mass Transfer.
The team analyzed the saliva that coats the respiratory drops that people throw out of their lungs. Scientists know that saliva allows many viruses to travel more than they would otherwise, enabling them to travel from one person to another.
The conventional wisdom is that aerosolic drops of a few microns produced in the lungs, which dry up in the air almost immediately, become harmful. But the team found that saliva changes the equation.
The team found that the mucous shell around the respiratory droplets potentially reduces the rate of evaporation, which increases the time it takes for the viral particles inside the droplets to disperse.
Envelope viruses, such as SARS-CoV-2, have a fatty coating that needs to be kept moist in order for the virus to be infected, so slow evaporation allows viral particles to stay infected longer.
“Many factors have been proposed as a variable of how the covid spreads,” Pace said, adding that “mucus is largely ignored.”
In a separate study published in the Indoor Air Journal, focusing on saliva also helped the team address how the virus circulates in a multiroom office building.
In the study, chemist Caroline Burns created artificial, respiratory drops to study how particles move from one room to another.
Scientists found that both low and high levels of filtering were effective in reducing the level of respiratory droplets in all rooms.
The team also found that increasing ventilation causes particle levels in the source room to drop faster.
But the particle level in the other connected room immediately jumped; After 20 to 45 minutes the level increased due to strong air changes.
Eventually, after the initial spike, the level of drops in all rooms gradually decreased after three hours with filtration and after five hours without it.
Scientists noted that increased air exchange for crowded spaces could be beneficial in certain situations, such as large conferences or school assemblies, but in normal working and school conditions, it could actually increase the transmission rate in all rooms of the building.
“If you’re in a downstream room and you’re not a source of the virus, you’re probably not better off with more ventilation,” Piz said.
(Inputs via IANS)
