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Talking Can Generate Coronavirus Droplets That Linger Up to 14 Minutes Talking Can Generate Coronavirus Droplets That Linger Up to 14 Minutes
(7 days later)
Coughs or sneezes may not be the only way people transmit infectious pathogens like the novel coronavirus to one another. Talking can also launch thousands of droplets so small they can remain suspended in the air for eight to 14 minutes, according to a new study.Coughs or sneezes may not be the only way people transmit infectious pathogens like the novel coronavirus to one another. Talking can also launch thousands of droplets so small they can remain suspended in the air for eight to 14 minutes, according to a new study.
The research, published Wednesday in The Proceedings of the National Academy of Sciences, could help explain how people with mild or no symptoms may infect others in close quarters such as offices, nursing homes, cruise ships and other confined spaces. The study’s experimental conditions will need to be replicated in more real-world circumstances, and researchers still don’t know how much virus has to be transmitted from one person to another to cause infection. But its findings strengthen the case for wearing masks and taking other precautions in such environments to reduce the spread of the coronavirus.The research, published Wednesday in The Proceedings of the National Academy of Sciences, could help explain how people with mild or no symptoms may infect others in close quarters such as offices, nursing homes, cruise ships and other confined spaces. The study’s experimental conditions will need to be replicated in more real-world circumstances, and researchers still don’t know how much virus has to be transmitted from one person to another to cause infection. But its findings strengthen the case for wearing masks and taking other precautions in such environments to reduce the spread of the coronavirus.
Scientists agree that the coronavirus jumps from person to person most often by hitching a ride inside tiny respiratory droplets. These droplets tend to fall to the ground within a few feet of the person who emits them. They may land on surfaces like doorknobs, where people can touch lingering virus particles and transfer them to their face. But some droplets can remain aloft, and be inhaled by others.Scientists agree that the coronavirus jumps from person to person most often by hitching a ride inside tiny respiratory droplets. These droplets tend to fall to the ground within a few feet of the person who emits them. They may land on surfaces like doorknobs, where people can touch lingering virus particles and transfer them to their face. But some droplets can remain aloft, and be inhaled by others.
Elaborate experiments have revealed how coughing or sneezing can produce a crackling burst of air mixed with saliva or mucus that can force hundreds of millions of influenza and other virus particles into the air if a person is sick. A single cough can propel about 3,000 respiratory droplets, while sneezing can generate as many as 40,000.Elaborate experiments have revealed how coughing or sneezing can produce a crackling burst of air mixed with saliva or mucus that can force hundreds of millions of influenza and other virus particles into the air if a person is sick. A single cough can propel about 3,000 respiratory droplets, while sneezing can generate as many as 40,000.
To see how many droplets are produced during normal conversation, researchers at the National Institute of Diabetes and Digestive and Kidney Diseases and the University of Pennsylvania, who study the kinetics of biological molecules inside the human body, asked volunteers to repeat the words “stay healthy” several times. While the participants spoke into the open end of a cardboard box, the researchers illuminated its inside with green lasers, and tracked bursts of droplets produced by the speaker.To see how many droplets are produced during normal conversation, researchers at the National Institute of Diabetes and Digestive and Kidney Diseases and the University of Pennsylvania, who study the kinetics of biological molecules inside the human body, asked volunteers to repeat the words “stay healthy” several times. While the participants spoke into the open end of a cardboard box, the researchers illuminated its inside with green lasers, and tracked bursts of droplets produced by the speaker.
The laser scans showed that about 2,600 small droplets were produced per second while talking. When researchers projected the amount and size of droplets produced at different volumes based on previous studies, they found that speaking louder could generate larger droplets, as well as greater quantities of them.The laser scans showed that about 2,600 small droplets were produced per second while talking. When researchers projected the amount and size of droplets produced at different volumes based on previous studies, they found that speaking louder could generate larger droplets, as well as greater quantities of them.
Although the scientists did not record speech droplets produced by people who were sick, previous studies have calculated exactly how much coronavirus genetic material can be found in oral fluids in the average patient. Based on this knowledge, the researchers estimated that a single minute of loud speaking could generate at least 1,000 virus-containing droplets.Although the scientists did not record speech droplets produced by people who were sick, previous studies have calculated exactly how much coronavirus genetic material can be found in oral fluids in the average patient. Based on this knowledge, the researchers estimated that a single minute of loud speaking could generate at least 1,000 virus-containing droplets.
The scientists also found that while droplets start shrinking from dehydration as soon as they leave a person’s mouth, they can still float in the air for eight to 14 minutes.The scientists also found that while droplets start shrinking from dehydration as soon as they leave a person’s mouth, they can still float in the air for eight to 14 minutes.
“These observations confirm that there is a substantial probability that normal speaking causes airborne virus transmission in confined environments,” the authors wrote in the study.“These observations confirm that there is a substantial probability that normal speaking causes airborne virus transmission in confined environments,” the authors wrote in the study.
The researchers acknowledged that the experiment was performed in a controlled environment with stagnant air that may not reflect what happens in rooms with good ventilation. But they still had reason to believe their reported values were “conservative lower limit estimates” because some people have a higher viral load, meaning they may produce droplets with several thousand more virus particles than average.The researchers acknowledged that the experiment was performed in a controlled environment with stagnant air that may not reflect what happens in rooms with good ventilation. But they still had reason to believe their reported values were “conservative lower limit estimates” because some people have a higher viral load, meaning they may produce droplets with several thousand more virus particles than average.
The Centers for Disease Control and Prevention says keeping at least six feet away from others can help people avoid contact with respiratory droplets and lower the risk of infection. But many scientists have argued that droplets can travel farther than six feet, depending on the force with which droplets are launched, the surrounding temperature, whether there are air currents that can carry them farther and other conditions.The Centers for Disease Control and Prevention says keeping at least six feet away from others can help people avoid contact with respiratory droplets and lower the risk of infection. But many scientists have argued that droplets can travel farther than six feet, depending on the force with which droplets are launched, the surrounding temperature, whether there are air currents that can carry them farther and other conditions.
Updated June 24, 2020 Updated June 30, 2020
Common symptoms include fever, a dry cough, fatigue and difficulty breathing or shortness of breath. Some of these symptoms overlap with those of the flu, making detection difficult, but runny noses and stuffy sinuses are less common. The C.D.C. has also added chills, muscle pain, sore throat, headache and a new loss of the sense of taste or smell as symptoms to look out for. Most people fall ill five to seven days after exposure, but symptoms may appear in as few as two days or as many as 14 days.
Scientists around the country have tried to identify everyday materials that do a good job of filtering microscopic particles. In recent tests, HEPA furnace filters scored high, as did vacuum cleaner bags, fabric similar to flannel pajamas and those of 600-count pillowcases. Other materials tested included layered coffee filters and scarves and bandannas. These scored lower, but still captured a small percentage of particles.Scientists around the country have tried to identify everyday materials that do a good job of filtering microscopic particles. In recent tests, HEPA furnace filters scored high, as did vacuum cleaner bags, fabric similar to flannel pajamas and those of 600-count pillowcases. Other materials tested included layered coffee filters and scarves and bandannas. These scored lower, but still captured a small percentage of particles.
A commentary published this month on the website of the British Journal of Sports Medicine points out that covering your face during exercise “comes with issues of potential breathing restriction and discomfort” and requires “balancing benefits versus possible adverse events.” Masks do alter exercise, says Cedric X. Bryant, the president and chief science officer of the American Council on Exercise, a nonprofit organization that funds exercise research and certifies fitness professionals. “In my personal experience,” he says, “heart rates are higher at the same relative intensity when you wear a mask.” Some people also could experience lightheadedness during familiar workouts while masked, says Len Kravitz, a professor of exercise science at the University of New Mexico.A commentary published this month on the website of the British Journal of Sports Medicine points out that covering your face during exercise “comes with issues of potential breathing restriction and discomfort” and requires “balancing benefits versus possible adverse events.” Masks do alter exercise, says Cedric X. Bryant, the president and chief science officer of the American Council on Exercise, a nonprofit organization that funds exercise research and certifies fitness professionals. “In my personal experience,” he says, “heart rates are higher at the same relative intensity when you wear a mask.” Some people also could experience lightheadedness during familiar workouts while masked, says Len Kravitz, a professor of exercise science at the University of New Mexico.
The steroid, dexamethasone, is the first treatment shown to reduce mortality in severely ill patients, according to scientists in Britain. The drug appears to reduce inflammation caused by the immune system, protecting the tissues. In the study, dexamethasone reduced deaths of patients on ventilators by one-third, and deaths of patients on oxygen by one-fifth.The steroid, dexamethasone, is the first treatment shown to reduce mortality in severely ill patients, according to scientists in Britain. The drug appears to reduce inflammation caused by the immune system, protecting the tissues. In the study, dexamethasone reduced deaths of patients on ventilators by one-third, and deaths of patients on oxygen by one-fifth.
The coronavirus emergency relief package gives many American workers paid leave if they need to take time off because of the virus. It gives qualified workers two weeks of paid sick leave if they are ill, quarantined or seeking diagnosis or preventive care for coronavirus, or if they are caring for sick family members. It gives 12 weeks of paid leave to people caring for children whose schools are closed or whose child care provider is unavailable because of the coronavirus. It is the first time the United States has had widespread federally mandated paid leave, and includes people who don’t typically get such benefits, like part-time and gig economy workers. But the measure excludes at least half of private-sector workers, including those at the country’s largest employers, and gives small employers significant leeway to deny leave.The coronavirus emergency relief package gives many American workers paid leave if they need to take time off because of the virus. It gives qualified workers two weeks of paid sick leave if they are ill, quarantined or seeking diagnosis or preventive care for coronavirus, or if they are caring for sick family members. It gives 12 weeks of paid leave to people caring for children whose schools are closed or whose child care provider is unavailable because of the coronavirus. It is the first time the United States has had widespread federally mandated paid leave, and includes people who don’t typically get such benefits, like part-time and gig economy workers. But the measure excludes at least half of private-sector workers, including those at the country’s largest employers, and gives small employers significant leeway to deny leave.
So far, the evidence seems to show it does. A widely cited paper published in April suggests that people are most infectious about two days before the onset of coronavirus symptoms and estimated that 44 percent of new infections were a result of transmission from people who were not yet showing symptoms. Recently, a top expert at the World Health Organization stated that transmission of the coronavirus by people who did not have symptoms was “very rare,” but she later walked back that statement.So far, the evidence seems to show it does. A widely cited paper published in April suggests that people are most infectious about two days before the onset of coronavirus symptoms and estimated that 44 percent of new infections were a result of transmission from people who were not yet showing symptoms. Recently, a top expert at the World Health Organization stated that transmission of the coronavirus by people who did not have symptoms was “very rare,” but she later walked back that statement.
Touching contaminated objects and then infecting ourselves with the germs is not typically how the virus spreads. But it can happen. A number of studies of flu, rhinovirus, coronavirus and other microbes have shown that respiratory illnesses, including the new coronavirus, can spread by touching contaminated surfaces, particularly in places like day care centers, offices and hospitals. But a long chain of events has to happen for the disease to spread that way. The best way to protect yourself from coronavirus — whether it’s surface transmission or close human contact — is still social distancing, washing your hands, not touching your face and wearing masks.Touching contaminated objects and then infecting ourselves with the germs is not typically how the virus spreads. But it can happen. A number of studies of flu, rhinovirus, coronavirus and other microbes have shown that respiratory illnesses, including the new coronavirus, can spread by touching contaminated surfaces, particularly in places like day care centers, offices and hospitals. But a long chain of events has to happen for the disease to spread that way. The best way to protect yourself from coronavirus — whether it’s surface transmission or close human contact — is still social distancing, washing your hands, not touching your face and wearing masks.
A study by European scientists is the first to document a strong statistical link between genetic variations and Covid-19, the illness caused by the coronavirus. Having Type A blood was linked to a 50 percent increase in the likelihood that a patient would need to get oxygen or to go on a ventilator, according to the new study.A study by European scientists is the first to document a strong statistical link between genetic variations and Covid-19, the illness caused by the coronavirus. Having Type A blood was linked to a 50 percent increase in the likelihood that a patient would need to get oxygen or to go on a ventilator, according to the new study.
The unemployment rate fell to 13.3 percent in May, the Labor Department said on June 5, an unexpected improvement in the nation’s job market as hiring rebounded faster than economists expected. Economists had forecast the unemployment rate to increase to as much as 20 percent, after it hit 14.7 percent in April, which was the highest since the government began keeping official statistics after World War II. But the unemployment rate dipped instead, with employers adding 2.5 million jobs, after more than 20 million jobs were lost in April.The unemployment rate fell to 13.3 percent in May, the Labor Department said on June 5, an unexpected improvement in the nation’s job market as hiring rebounded faster than economists expected. Economists had forecast the unemployment rate to increase to as much as 20 percent, after it hit 14.7 percent in April, which was the highest since the government began keeping official statistics after World War II. But the unemployment rate dipped instead, with employers adding 2.5 million jobs, after more than 20 million jobs were lost in April.
Common symptoms include fever, a dry cough, fatigue and difficulty breathing or shortness of breath. Some of these symptoms overlap with those of the flu, making detection difficult, but runny noses and stuffy sinuses are less common. The C.D.C. has also added chills, muscle pain, sore throat, headache and a new loss of the sense of taste or smell as symptoms to look out for. Most people fall ill five to seven days after exposure, but symptoms may appear in as few as two days or as many as 14 days.
If air travel is unavoidable, there are some steps you can take to protect yourself. Most important: Wash your hands often, and stop touching your face. If possible, choose a window seat. A study from Emory University found that during flu season, the safest place to sit on a plane is by a window, as people sitting in window seats had less contact with potentially sick people. Disinfect hard surfaces. When you get to your seat and your hands are clean, use disinfecting wipes to clean the hard surfaces at your seat like the head and arm rest, the seatbelt buckle, the remote, screen, seat back pocket and the tray table. If the seat is hard and nonporous or leather or pleather, you can wipe that down, too. (Using wipes on upholstered seats could lead to a wet seat and spreading of germs rather than killing them.)If air travel is unavoidable, there are some steps you can take to protect yourself. Most important: Wash your hands often, and stop touching your face. If possible, choose a window seat. A study from Emory University found that during flu season, the safest place to sit on a plane is by a window, as people sitting in window seats had less contact with potentially sick people. Disinfect hard surfaces. When you get to your seat and your hands are clean, use disinfecting wipes to clean the hard surfaces at your seat like the head and arm rest, the seatbelt buckle, the remote, screen, seat back pocket and the tray table. If the seat is hard and nonporous or leather or pleather, you can wipe that down, too. (Using wipes on upholstered seats could lead to a wet seat and spreading of germs rather than killing them.)
If you’ve been exposed to the coronavirus or think you have, and have a fever or symptoms like a cough or difficulty breathing, call a doctor. They should give you advice on whether you should be tested, how to get tested, and how to seek medical treatment without potentially infecting or exposing others.If you’ve been exposed to the coronavirus or think you have, and have a fever or symptoms like a cough or difficulty breathing, call a doctor. They should give you advice on whether you should be tested, how to get tested, and how to seek medical treatment without potentially infecting or exposing others.
There is also debate about whether the coronavirus can also be transmitted through even smaller droplets — less than a tenth the width of a human hair — that are known as aerosols, and can remain suspended or travel through the air for longer.There is also debate about whether the coronavirus can also be transmitted through even smaller droplets — less than a tenth the width of a human hair — that are known as aerosols, and can remain suspended or travel through the air for longer.
In another recent study, the same authors showed that just articulating certain sounds can produce significantly higher amounts of respiratory particles. The “th” sound in the word “healthy,” for example, was a very efficient generator of speech droplets. Another paper, published in January by researchers from the University of California, Davis, found the vowel sound “e” in “need” produces more droplets than the “a” in “saw,” or “o” in “mood.”In another recent study, the same authors showed that just articulating certain sounds can produce significantly higher amounts of respiratory particles. The “th” sound in the word “healthy,” for example, was a very efficient generator of speech droplets. Another paper, published in January by researchers from the University of California, Davis, found the vowel sound “e” in “need” produces more droplets than the “a” in “saw,” or “o” in “mood.”
What researchers don’t yet know is whether all speech, cough and sneeze droplets carrying virus particles are equally infectious, or if a specific amount of virus needs to be transmitted for a person to get sick by breathing it in.What researchers don’t yet know is whether all speech, cough and sneeze droplets carrying virus particles are equally infectious, or if a specific amount of virus needs to be transmitted for a person to get sick by breathing it in.
But the new study adds to the case for maintaining a physical distance from other people to help slow the spread of coronavirus, said Linsey Marr, a professor of civil and environmental engineering at Virginia Tech who was not involved with the paper.But the new study adds to the case for maintaining a physical distance from other people to help slow the spread of coronavirus, said Linsey Marr, a professor of civil and environmental engineering at Virginia Tech who was not involved with the paper.
“Based on this and other evidence, it would be wise to avoid extended face-to-face conversations with other people unless you are far apart and in a well-ventilated space, including outdoors,” Dr. Marr said.“Based on this and other evidence, it would be wise to avoid extended face-to-face conversations with other people unless you are far apart and in a well-ventilated space, including outdoors,” Dr. Marr said.
The study also highlights the importance of wearing masks during social and other interactions.The study also highlights the importance of wearing masks during social and other interactions.
“The risk of talking to one another will probably be lower than being exposed to a person who is not wearing a mask and openly coughs and sneezes,” said Dr. Werner E. Bischoff, the medical director of infection prevention and health system epidemiology at the Wake Forest School of Medicine. “Normal talking to a person while keeping the recommended social distance will be fine. Putting on a mask will be even better.”“The risk of talking to one another will probably be lower than being exposed to a person who is not wearing a mask and openly coughs and sneezes,” said Dr. Werner E. Bischoff, the medical director of infection prevention and health system epidemiology at the Wake Forest School of Medicine. “Normal talking to a person while keeping the recommended social distance will be fine. Putting on a mask will be even better.”