Coronavirus is spread through the air, especially in indoor spaces. While it is not as contagious as measles, scientists now openly acknowledge the role played by the transition to aerosols – tiny infectious particles inhaled by an infected person that remain trapped in the air in the home environment. How does the transmission work? And, most importantly, how can we prevent it?
These are respiratory drops with a diameter of less than 100 micrometers Can be suspended in the air for hours
1,200 aerosols are released for each droplet
These are particles that are larger than 300 micrometers and, due to air flow, Fell to the ground in seconds
These are respiratory drops with a diameter of less than 100 micrometers Can be suspended in the air for hours
1,200 aerosols are released for each droplet
These are particles that are larger than 300 micrometers and, due to air flow, Fell to the ground in seconds
These are respiratory drops with a diameter of less than 100 micrometers Can be suspended in the air for hours
1,200 aerosols are released for each droplet
These are particles that are larger than 300 micrometers and, due to air flow, Fell to the ground in seconds
These are respiratory drops with a diameter of less than 100 micrometers Can be suspended in the air for hours
These are particles that are larger than 300 micrometers and, due to air flow, Fell to the ground in seconds
1,200 aerosols are released for each droplet
These are respiratory drops with a diameter of less than 100 micrometers Can be suspended in the air for hours
These are particles that are larger than 300 micrometers and, due to air flow, Fell to the ground in seconds
1,200 aerosols are released for each droplet
Currently, health officials identify three vehicles of coronavirus transmission: small drops from speaking or coughing, which can end up in the eyes, mouth or nose of people standing nearby; Contaminated surfaces (fomits), although U.S. The Centers for Disease Control and Prevention (CDC) suggests that this is the least likely way to catch the virus, with European Centers for Disease Control and Prevention (ECDC) monitoring confirming that a case of Covid-19 has been found; Then finally, there is the transmission through aerosols – the inhalation of invisible infectious particles exhaled by an infected person which, once left the mouth, behaves in the same way as smoking. Without ventilation, aerosols remain suspended in the air and become more and more volatile over time.
Without ventilation, aerosols remain suspended in the air, increasing in proportion over time.
Breathing, speaking and booming
At the beginning of the epidemic, it was thought that when we coughed or sneezed, the large droplets we expelled were the main means of transmission. But now we know that screaming and singing in indoor, poorly ventilated areas for a long time also increases the risk of infection. This is because speaking out loud releases 50 times more virus-filled particles than we do speaking out. These aerosols, if not dispersed by ventilation, become increasingly concentrated, increasing the risk of infection. Scientists have shown that these particles – which we only release into the atmosphere when we breathe and that can escape improperly worn face masks – can infect people who spend more than a few minutes within a five-meter radius of an infected person. Depending on the length of time and the nature of the interaction. In the following example, we have shown which conditions increase the risk of becoming infected in this situation.
Each Orange dot Presents Respiratory dose
Particles capable of infecting If someone is breathing
We go out 10 times Number of particles Than when there is silence
We go out 50 times Number of particles We scream rather than scream
In a bad situation – screaming or singing in an enclosed space for an hour – the person with the covid-19 is released 1,500 infectious doses.
Each Orange dot Presents Respiratory dose
Particles capable of infecting If someone is breathing
We go out 50 times Number of particles We scream rather than scream
We go out 10 times Number of particles Than when there is silence
In a bad situation – screaming or singing in an enclosed space for an hour – the person with the covid-19 is released 1,500 infectious doses.
Each Orange dot Presents The amount of respiratory particles capable
Of infection If someone is breathing
We go out 10 times Number of particles Than when there is silence
We go out 50 times Number of particles We scream rather than scream
In a bad situation – screaming or singing in an enclosed space for an hour – the person with the covid-19 is released 1,500 infectious doses.
In the spring, health officials failed to focus on aerosol transmission, but recent scientific publications have forced the World Health Organization (WHO) and the CDC to accept it. A reputable article Science The magazine found that there was “overwhelming evidence” that airborne transmission was the “main transmission route” for the coronavirus, and the CDC noted that “in some situations, they would infect others who were more than six feet tall.” [two meters] Away these transmissions took place between closed spaces with inadequate ventilation. Sometimes an infected person breathes heavily, for example, while singing or exercising. ”
A bar or restaurant
Coronavirus outbreaks occur at events, and in bouts such as bars and rest restaurants rent, there are a significant number of transitions to social settings. What’s more, it’s the most explosive: an average of 27 people are infected with each outbreak in a nightclub, compared to just six during a family reunion – as explained in the first graphic. One of the major outbreaks occurred at a club in the southern city of Cડોrdoba, Spain, where 73 people tested positive after one night. Scientists have also recently analyzed an outbreak at a bar in Vietnam, where 12 supporters were infected with the virus.
School
Only 6% of schools reported coronavirus outbreaks reported by Spanish health officials. The dynamics of transmission through aerosols in the classroom vary completely depending on whether the infected person – or patient zero – is a student or a teacher. Teachers talk a lot more than students and listen to their voices, which is many times more likely to expel potentially infectious particles. In comparison, an infected student will speak only occasionally. According to guidelines from the Spanish National Research Council (CSIC), the Spanish government recommends ventilating classrooms – although this can cause discomfort during the colder months – or the use of ventilation units.
To calculate the likelihood of a transition between people in “dangerous” situations, we used the Covid Airborne Transmission Estimator, developed by a group of scientists led by Professor Jose Luis Jimenez of the University of Colorado. This tool aims to highlight the importance of barrier measures in aerosol transmission. The calculation is not exhaustive or it covers all the numerous variables that can affect the transmission, but it explains how the risk of infection can be reduced by the changing conditions we can control.
During simulations, subjects maintain the recommended safe distance, eliminating the risk of transmission by drops. But they can become infected if possible preventive measures are not applied simultaneously: proper ventilation, shortening the encounter, reducing the number of participants and wearing a face mask. The ideal scenario, whatever the context, may be outside, where infectious particles are rapidly dispersed. If a safe distance from an infected person is not maintained, the probability of transmission is multiplied because there can also be a risk of being infected by drops – not just aerosols. To make matters worse, even if there is ventilation, it would not be enough to spread the rosels if those people were together.
The calculations shown in three different scenarios are based on a study of how aerosol transmission occurs, using actual fractions analyzed in detail. In March, in the United States, and in Washington State, Washington, there was a very relevant case in terms of understanding the dynamics of indoor transmission. Only 61 of the singer’s 120 members attended the rehearsals, and efforts were made to maintain safe distance and hygiene measures. But unfamiliar to them, they were in the scene of maximum danger: no longer a mask, no ventilation, no place to sing and share. Only one infected person transmitted the virus to 53 people within two hours. Some of the infected were 14 meters away, so only aerosols would explain its transmission. Two of the people who caught the virus died.
Cases of corona virus
13-15 days in rehearsal
a An infected person Everyone else in the front row became infected.
Cases of corona virus
13-15 days in rehearsal
a An infected person Sitting in the front row, everyone else got infected.
Cases of corona virus
13-15 days in rehearsal
a An infected person Sitting in the front row, everyone else got infected.
After carefully studying the outbreak, scientists were able to calculate the extent to which the risk could have been reduced if they had taken action against aerated transmission. For example, if masks had been worn, the risk would have been halved and only 44% of those present would have been affected as opposed to 87%. If rehearsals had been held in a short space of time with more ventilation, only two singers would have been infected. These mass-spreading scenarios seem to be crucial to the development and spread of an increasingly epidemic, meaning that the key to controlling such events is to have the means to prevent large-scale transmission.
Method: We calculated the risk of infection using a tool developed by Jose Louis Jimenez, an atmospheric chemist from the University of Colorado and an expert in the chemistry and dynamics of air particles from Covid-19. Scientists around the world have reviewed these estimates, based on published methods and data for estimating the importance of the various measurement factors involved in infection scenarios. However, the accuracy of the estimate is limited because it still depends on an indefinite number – the numbers that describe, for example, how many infectious viruses are emitted by an infected person. Estimators assume that people study the law of two-meter social distance and have no immunity. Our calculations are based on the default default value for the general population, which includes a wide range of masks (surgical and cloth), and loud noises, which increase the amount of aerosols emitted.
Videos by Louis Almodivar.
English version by Heather Galloway.
