In July, 239 scientists from 32 countries urged the World Health Organization (WHO) to acknowledge the potential role of air broadcast in the spread of SARS-CoV-2.
After three days, the WHO stated that under certain conditions, “short-range aerosol transmission did not rule out long-term infected individuals, especially in specific indoor locations, such as congested and inadequately ventilated locations.” can go.”
Many scientists expressed happiness on social media when the CDC agreed, acknowledging for the first time in a September 18 website update that aerosols play a meaningful role in the spread of the virus. The update states that COVID-19 can spread through small drops or small particles, such as As in those in aerosols, when an infected person coughs, sneezes, sings, Conversation or breath. These particles can get into the nose, mouth, airways and lungs and cause infection. It is believed to be the main method of spreading the virus. ”
However, the controversy arose when, three days later, the CDC correctly took that guidance, stating that it was posted in error, without proper review.
Right now, the CDC website does not acknowledge that aerosols typically extend SARS-CoV-2 beyond 6 feet, instead: “COVID-19 primarily spreads among those that are long (about 6 feet) Within) contact. It occurs when an infected person coughs, sneezes or talks, and drops are released from their mouth or nose into the air and into the mouth or nose of nearby people. The drops can also go into the lungs. “
The site says that respiratory droplets can land on various surfaces, and people can become infected by touching those surfaces and then touching their eyes, nose, or mouth. It states, “Current data do not support long-range aerosol transmission of SARS-CoV-2, as seen with measles or tuberculosis. Short-range inhalation of aerosols is a possibility for COVID-19 , As with many respiratory pathogens. However, this cannot be easily distinguished from ‘droplet’ transmission based on epidemiological patterns. Short-range transmission is a possibility, especially in crowded medical wards and insufficiently. .. “
Confusion has surrounded the use of terms such as “aerosol” and “drops” as they are not consistently defined. And the term “airborne” holds special meaning for infectious disease specialists and public health officials because of the question of whether the infection can be easily spread by “airborne transmission”. If SARS-CoV-2 is easily spread by aerial transmissions, more stringent infection control measures will need to be adopted, as with airborne diseases such as measles and tuberculosis. But the CDC called CBS News Chief Medical Correspondent Dr. Jonathan has told La Puc that even though airborne spread is playing a role with SARS-COV-2, this role does not seem nearly as important as it does with aerial infections such as ankles and tuberculosis.
All of this may sound like a whiskey scientific discussion that is deep in weeds – and it is – but it has big implications as people try to figure out how to be safe during an epidemic. Some pieces of advice are intuitively clear: wear a mask, wash your hands, avoid crowds, keep your distance from others, safer than indoors. But what about that “6-foot” rule to maintain social distance? If the virus can travel indoors for a distance of more than 6 feet, isn’t it logical to wear a mask whenever you’re not part of your “pod” or “bubble”?
Understanding the basic science behind how SARS-CoV-2 travels through the air should help us strategize to stay safe. Unfortunately, there are still many open questions. For example, even though an aerosol manufactured by an infected person can float in a room, and even if the aerosol contains some viable viruses, how do we know how important a potential mode of transmission is in an epidemic?
As we await responses to ongoing research, Drs. Lacup turned to three prominent scientists to try to clear the air. While acknowledging that science is still not set in stone, they have generously agreed to give us their best advice on how to think about protecting ourselves, the way SARS-CoV-2 can spread. Below, atmospheric chemist Kimberly Prather, airborne virus specialist Linsey Marr and environmental health professor Donald Milton discuss the best precautions to reduce their risk of infection.
Contrary to early thinking about the importance of transmission by contact with large respiratory droplets, the finding that a major way to become infected with the virus is to infect people. This is most common when a person is within 6 feet of a person who has COVID-19 (with or without symptoms), but can also be more than 6 feet away.
Viruses in small, airborne particles called aerosols can infect people both near and long distances. Aerosols can be thought of as cigarette smoke. While they are closest to someone with an infection, they can go more than 6 feet away, ginger, build up in the air and remain infectious for hours. As a result, to reduce the chance of reducing this virus, it is important to take all of the following steps:
Practice physical distancing – the better.
Wear a face mask when you are with others, even when you can maintain physical distance. Face masks not only reduce the amount of virus in people who have an infection, but it also makes you less likely to get a virus infection.
Improve ventilation by opening windows. Learn to clean the air effectively by methods such as filtration.
Wear a face mask if you cannot physically walk at least 6 feet or ideally longer.
Whenever possible, carry out group activities.
Whether you are indoors or outdoors, remember that your risk increases with the duration of exposure to others.
With the question of transmission, it is not just the public that has become confused. There is also confusion among scientists, medical professionals, and public health officials, as they have often used the terms “drops” and “aerosols” differently. To clear up the confusion, participants at an August workshop on aerial transmissions of SARS-CoV-2 at the National Academies of Science, Engineering and Medicine unanimously agreed on these definitions for respiratory drops and aerosols:
Drops Are larger than 100 microns and fall to the ground within 6 feet, traveling like small cannons.
Aerosol Are smaller than 100 microns, are extremely close to a person, can travel more than 6 feet away and can move around in air, especially in rooms with poor ventilation.
All respiratory activities, including breathing, talking, and singing, produce far more aerosols than droplets. Even at short distances a person is more likely to inhale aerosols than when sprayed by a droplet. The exact percentage of transmission by droplets versus aerosols is still to be determined. But we know from epidemiology and other data, especially superseding events, that infection occurs through inhalation of aerosols.
In short, how are we getting infected with SARS-CoV-2? The answer is: in the air. Once we accept this, we can use tools that help end this epidemic.
Kimberly A. Pather, PhD, Distinguished Chair in Atmospheric Chemistry, Scripps Institution of Oceanography, UC Diego.
Linsey C. Marr, PhD, Charles P. Lunford Professor of Civil and Environmental Engineering, Virginia Tech.
Donald K. Milton, MD, DrPH, Professor of Environmental Health at Maryland School of Public Health.