Three scientists give the best advice on how to protect yourself from COVID-19

Over the past few months, there has been controversy over SARS-CoV-2, the method of the causative virus. COVID-19 (new coronavirus infection) (# If there is no character limit, add parentheses when it first appears, Move from infected to others. Official guidance is often unclear, but some aerosol scientists and public health professionals say that the spread of the virus in aerosols traveling in the air at distances of less than 6 feet and more than 6 feet is more important than assessment. Claims to play a role.

July, 239 scientists from 32 countries Prompted The World Health Organization (WHO) recognizes the possible role of aerial transmission in the spread of SARS-CoV-2.

Three days later, WHO did, State Under certain conditions, “short-range aerosol infections cannot be ruled out, especially in areas where the infected person is congested for a long period of time and is poorly ventilated.”

When the CDC seemed to agree, many scientists were delighted on social media and first acknowledged in a September 18 website update that aerosols play a meaningful role in the spread of the virus. The update states that COVID-19 “may spread through respiratory droplets or small particles.” Something like an aerosol produced when an infected person coughs, sneezes, or sings a song Talk and breathe. These particles are inhaled into the nose, mouth, respiratory tract, and lungs and can cause infections. This is believed to be the main way the virus spreads. ”

But three days later, the controversy arose again, saying that the CDC withdrew its guidance and was mistakenly posted without proper review.

Currently, the CDC website does not allow aerosols to spread normally beyond SARS-CoV-2 over 6 feet. saying: “COVID-19 spreads primarily to people in close contact for long periods of time (within about 6 feet). The spread is that infected people cough, sneeze, or talk, and droplets from the mouth and nose are in the air. It is released into the mouth and nose of nearby people. Droplets can also be inhaled into the lungs. “

According to this site, Flügge Droplets can land on various surfaces, and people touch Touch their surface and then their eyes, nose or mouth. In addition, “Current data do not support long-distance aerosol infections of SARS-CoV-2, as seen in measles and tuberculosis. Like many respiratory pathogens, short-range inhalation of aerosols The possibility of COVID-19 .. However, this is not easily distinguishable from “droplet” infections based on epidemiological patterns. Short-distance infections can occur, especially when inadequate in crowded wards. Ventilated space“

Words such as “aerosol” and “droplet” are not consistently defined, causing confusion. The term “airborne transmission” also has a special meaning to infectious disease professionals and public health authorities due to the question of whether “airborne transmission” can easily spread the infection. If SARS-CoV-2 is easily spread by airborne transmission, stricter infection control measures should be adopted, similar to airborne infections such as measles and tuberculosis. However, the CDC told CBS News Chief Medical Correspondent Dr. Jonathan Lapouk that even if airborne spread plays a role in SARS-CoV-2, that role is not as important as airborne infections such as measles and tuberculosis. He said it seems.

All this may sound like a weird scientific debate deep inside weeds, but it has a big impact as people try to understand how to stay safe during a pandemic. Some advice is intuitively clear. Wear a mask, wash your hands, avoid crowds, stay away from others, and be safer outdoors than indoors. But what about the “6 feet” rule for maintaining social distance? It is logical to wear a mask indoors whenever you are with someone who is not part of a “pod” or “bubble” if the virus can travel indoors more than 6 feet. Is there?

Understanding the basic science behind how SARS-CoV-2 travels in the air should help give us a strategy to stay safe. Unfortunately, there are still many open questions. For example, an aerosol produced by an infected person can float across a room, and even if the aerosol contains a viable virus, how important is that possible transmission mode in the pandemic? How can I find out?

While waiting for responses from ongoing research, Dr. Rapook asked three key scientists to clean the air. He acknowledged that science has not yet been finalized and generously agreed to give the best advice on how to think about protecting himself, based on his current understanding of how SARS-CoV-2 spreads. Below, atmospheric chemist Kimberly Placer, aerial virus expert Lindsaymer, and environmental hygiene professor Donald Milton describe the best precautions to reduce the risk of infection.

Clean the air

In contrast to early thoughts about the importance of infection by contact with large respiratory droplets, it turned out that the main way people get infected is to inhale the virus. This is most common when standing within 6 feet of a person with COVID-19 (with or without symptoms), but can also occur more than 6 feet away.

Viruses in small airborne particles called aerosols can infect people both at short and long distances. Aerosols can be thought of as cigarette smoke. They are most concentrated near the infected person, but can travel more than 6 feet, stay longer, accumulate in the air, and remain infected for hours. As a result, it is important to perform all of the following steps to reduce the chance of inhaling this virus.

indoor:

• Practice physical distance — the farther the better.

• Wear a face mask when you are with others, even if you can keep a physical distance. Face masks not only reduce the amount of virus from infected people, but also reduce the chances of inhaling the virus.

• Open the windows to improve ventilation. Learn how to effectively clean the air, such as by filtering.

Outdoors:

• Wear a face mask if you cannot physically reach at least 6 feet, ideally more.

• Whenever possible, move group activities to the outside.

Remember that your risk increases with the duration of contact with others, whether you are indoors or outdoors.
The general public is not the only one who is confused by communication issues. There is also confusion among scientists, medical professionals and public health authorities. This is because the terms “droplet” and “aerosol” are often used differently. To address the turmoil, participants in the August workshop on airborne transmission of SARS-CoV-2 at the National Academy of Science and Technology Medicine unanimously agreed with these definitions of respiratory droplets and aerosols.

• splash Larger than 100 microns, it falls to the ground within 6 feet and moves like a small shell.

• aerosol Less than 100 microns, it is very concentrated near people, can move over 6 feet, and can remain and accumulate in the air, especially in poorly ventilated rooms.

All respiratory activity, including breathing, conversation, and singing, produces far more aerosols than droplets. A person is much more likely to inhale an aerosol than it is sprayed by a droplet, even at short distances. The exact percentage of droplet permeation of the aerosol has not yet been determined. However, epidemiological and other data, especially hyperspread events, indicate that inhalation of aerosols causes infection.

In short, how are you infected with SARS-CoV-2? The answer is: in the air. Once you acknowledge this, you can use the tools you already need to end this pandemic.

Dr. Kimberly A. Placer, Prominent Chair of Atmospheric Chemistry, Scripps Institution of Oceanography, University of California, San Diego.

Dr. Lindsay C. Marr, Professor of Civil and Environmental Engineering, Virginia P. Landsford Virginia Tech.

Donald K Milton, MD, DrPH, Professor of Environmental Health, Faculty of Public Health, University of Maryland.