Police departments have used tear gas and pepper spray on protesters in recent weeks, raising concern that the chemical agents could increase the spread of the coronavirus .
The chemicals are designed to irritate the mucous membranes of the eyes, nose, and throat. They make people cough, sneeze, and pull off their masks as they try to breathe .
Medical experts say those rushing to help people sprayed by tear gas could come into close contact with someone already infected with the virus who is coughing infectious particles . Also, those not already infected could be in more danger of getting sick because of irritation to their respiratory tracts .
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There is no research on tear gas and COVID-19 specifically because the virus is too new. But a few years ago, Joseph Hout , then an active-duty Army officer, conducted a study of 6,723 Army recruits exposed to a riot control gas during basic training. The study found a link between that exposure and doctors diagnosing acute respiratory illnesses .
Could tear gas lead to an increase in coronavirus infections ? "I think it's plausible, yes," Hout said Monday.
The gases and sprays "by their nature, make you cough, sneeze, and excrete fluids ," said Hout, now employed by Fairfax, Virginia-based Knowesis Inc., a private contractor.
"If there is a person who is positive for the virus , I can see them coughing on someone else and spreading it that way," Hout said. "Another less likely way is through irritation of the respiratory system . It could create an environment for opportunistic infection in the body."
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Last week, more than 1,000 medical professionals and students signed a letter urging public health officials to oppose any use of " tear gas , smoke , or other respiratory irritants , which could increase the risk for COVID-19 by making the respiratory tract more susceptible to infection, exacerbating existing inflammation, and inducing coughing."
In the U.S., mayors in Portland , Oregon , and Seattle have ordered limits on the use of one common gas for crowd control. A judge in Denver imposed restrictions on the use of chemical weapons by police. And officials in Pittsburgh , New Orleans and Washington, D.C. , have proposed bans or limits on tear gas use.
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As protests over the death of George Floyd and other black Americans killed by law enforcement continue, it will take weeks before the effect might show up in rising COVID-19 case numbers. If cases increase, there are other factors that could share the blame, such as shouting , singing , and, for thousands who were arrested, being confined in close spaces with others.
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