When the COVID-19 Superspreader is talking, it’s important where you are sitting in the room

It doesn’t take long for coronavirus particles in the air to pass through the room. Initially, only those sitting near the infected speaker are at increased risk, but as meetings and classes progress, Small aerosol Can spread.

But that doesn’t mean that everyone faces the same level of risk.

So Engineers, I have been experimenting with tracking how aerosols work. Can carry the virus..

It’s important to understand what I’ve found, as more people return to college, offices, restaurants, and more meetings move indoors as the temperature drops.Shows the most risky areas of the room and why Proper ventilation is important..

As I saw last week With President Donald Trump and others in WashingtonIf no precautions are taken, the coronavirus can spread quickly. The university campus also suffers from COVID-19. Cases aged 18 to 22 years More than double In the Midwest and Northeast after school reopened in August.

As the number of cases increases, so does the risk to those who spend time in those rooms.

Experiments show who is at greatest risk

The latest model to explain the role of ventilation The fate of airborne microorganisms in the room Assume that the air is well mixed and the particle concentration is uniform throughout. In poorly ventilated rooms and tight spaces, that’s probably true. In these scenarios, the entire room is a high-risk area.

However, in large spaces such as classrooms, proper ventilation reduces the risk but may not be uniform. According to my research, the level of risk is highly dependent on ventilation.

To understand how the coronavirus spreads, aerosol particles of the same size as humans were injected into the room and monitored by sensors.We used a 30ft x 26ft college classroom designed to accommodate 30 students with a ventilation system Recommended criteria..

When the particles were released in front of the classroom, they reached the back of the room within 10 to 15 minutes. However, due to the active ventilation in the room, the concentration on the back, about 20 feet away from the source, was about one-tenth that close to the source.

This suggests that with proper ventilation, the highest risk of contracting COVID-19 may be limited to a small number of people near the infected speaker. However, if you spend more time indoors with infected speakers, the risk spreads throughout the room, even with good ventilation.

CDC finally recognizes aerosol risk

So far, the transmission of respiratory illness has focused on the role of large particles that occur when sneezing or coughing.These droplets quickly fall to the ground, with social distance Wearing a mask Infection from them can be significantly prevented.

The bigger concern now is Small particles known as aerosols What is produced when we speak, sing Or just breathe. These particles are often less than 5 micrometers and can escape from the cloth mask. Stay in the air for up to about 12 hours..Centers for Disease Control and Prevention is finally here Acknowledged the risk October 5 after Trump was hospitalized and some other people in or near the administration tested positive for COVID-19.

On average, these small particles carry less virus than the larger particles released when coughing or sneezing, but with the high infectivity of SARS-CoV-2. High viral load Before symptoms appear, these particles are important for the transmission of aerial disease.

How much ventilation is enough?

Top of CDC to minimize COVID-19 infection indoors Recommendation Eliminating the source of infection. Remote learning does this effectively on many campuses. For face-to-face education, engineering means such as ventilation, partition shields, and filtration units can remove particles directly from the air.

Of all engineering controls, ventilation is probably the most effective tool for minimizing the spread of infection.

Understanding how ventilation reduces the risk of transmitting COVID-19 begins with the air exchange rate. An hourly air exchange means that the amount of air supplied to the room over an hour is equal to the amount of air in the room.Air exchange rate Range less than 1 for home use Around 15-25 for hospital operating rooms..

For classrooms, current primary airflow regulations support about 6 air exchanges per hour. That is, every 10 minutes, the amount of air brought into the room is equal to the volume of the room.

How high the concentration is depends in part on the number of people in the room, the amount they release, and the rate of air exchange. The air in many indoor spaces is actually cleaner than it was before the pandemic, as social distance cuts the classroom population in half and everyone wears masks.

Part of the room to avoid

It is important to remember that not all parts of the room are at the same risk.

Particles can remain there longer, as air exchange is likely to be less in the corners of the room.

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Being close to the air outlet vents can mean that airborne particles from the rest of the room can wash you away.Research Ventilation airflow in Chinese restaurants It traced its role in some COVID-19 illnesses among its patrons.

Approximately 95% of the particles in the room are removed by functioning properly Ventilation system in 30 minutesHowever, infected persons in the room mean that those particles are also continuously released. The pace of particle removal can be accelerated by increasing the air exchange rate or by adding other engineering controls such as filtration units. Opening the windows often increases the effective air exchange rate.

Schools, restaurants, malls and other communal spaces begin to accommodate more people indoors, understand the risks, CDC Recommendations Helps minimize the spread of the infection.

This story has been updated with CDC’s new guidance on aerosols.