How safe is it to attend an event or meeting in the middle of the covid-19 pandemic?
With the number of cases still on the rise around the world, you may wonder how wise it is to attend that family reunion or that birthday you were invited.
A study led by researchers from the University of Oxford, in the United Kingdom, and the Massachusetts Institute of Technology (MIT, for its acronym in English), in the United States, wants to help the public to assess the risk in each situation.
For this, they devised a table that classifies the risk according to the number of attendees, whether or not they wear masks, the activity they do (if they speak, sing, shout or are silent) and the level of ventilation of the premises.
He Original article it was published in the British Medical Journal.
“The risk of infection is determined by many factors and they are all connected. There is no study yet that determines the absolute risk, but we want to empower people to assess the risk of infection. risk relative to each situation“Lydia Bourouiba, director of the laboratory of fluid dynamics in disease transmission at the Massachusetts Institute of Technology (MIT, for its acronym in English) and one of the authors of the study, tells BBC Mundo.
For example, if you are invited to karaoke in a closed room where people will be shouting and singing, it is advisable to stay as little as possible and make sure that there will be few people. Without forgetting to use the mask.
Or perhaps you can suggest a meeting with the same friends in an open place, where it is possible to maintain a greater distance between the attendees. Avoid loud music so you don’t have to yell.
Distance, ventilation and time
More recent studies show that viruses can be dispersed in airborne droplets up to six to eight meters, depending on the situation. For this reason, the researchers argue in the article that the recommended two meters of distance must be, in some cases, the minimum distance – not the maximum – to maintain with someone.
“The two meter rule did not consider the total picture of the exhalation of suspended particles in the air and how they move. Today we know that it is not just because you keep those two meters away that you are safe,” says Bourouiba.
This is where other factors considered in the graph come in, such as the duration of the event or the time one remains in contact with the attendees.
But what exactly is a short or long period? According to the researcher, it is still difficult to answer that question.
“Some health agencies are considering that more than 15 minutes it is a long period. But there is no scientific justification to support that figure. So we decided not to specify it in the table, “he explains.
In the same way, defining whether an event has a high or low occupancy, according to Bourouiba, does not depend only on how many people are in the premises.
It is also important to know if there are enough fresh air and that the assistants are not within the alien breathing zone. That is, there must be more than 25 centimeters of distance between the mouth and the nose of one (who breathes normally) and the other.
“Each person must have at least 10 to 15 liters of fresh air per second. We do not have how to calculate that in our day to day life, but that is an important measure for owners of event spaces, restaurants, offices, etc. They have to know if those spaces need to be expanded or renovated, “he warns.
The most important thing, says Bourouiba, is to ensure the circulation of clean air, preferably from outside. “It is not enough to move the air, like a fan or air conditioning does. You have to renew it to dilute the particles that we exhale into the new air.”
For that reason, it is better to be in open or windowed spaces that allow air to circulate. And still, it is important to watch how it circulates.
“In a restaurant, for example, if there are customers in front of an open window, the air will always pass through these people, taking their germs with it and possibly transmitting them to other people,” says the MIT researcher.
What to do in each situation?
According to Lydia Bourouiba, some basic care should be taken in each situation in the table:
- Rlow risk– Try to keep at least two meters away and use the mask. “Not because you are six feet away means you can take off your mask and not because you wear the mask means you can be closer to people,” he says.
- Rmedium risk – Be more rigorous with the two meter rule. If possible, take a little more distance depending on the other factors.
- High risk – Two meters should be the minimum distance, although the ideal is to be further away and use a good quality mask.
“We know that it is complicated, but we try to organize the information in a way that everyone understands, from the family that wants to organize a barbecue to the office manager. We will all have to handle these situations.”, Concludes the scientist.
Remember that you can receive notifications from BBC News Mundo. Download the latest version of our app and activate them so you don’t miss out on our best content.
MORE NEWS -:
How do you know if you have COVID-19, the flu, or a cold?
Click to see the full video