Talking to a friend when infected with a coronavirus can be as dangerous as a cough near them, thanks to delayed particles, research suggests.
Covid is spread in many ways, in which an infected person exposes the virus when it breathes, speaks or coughs – a factor experts say helped explain why covid spreads more easily in indoor settings. Can.
Large drops fall to the ground at short distances, while small droplets called aerosols can carry the virus over a distance of more than two meters, and spread.
Now experts have developed models to explore the danger posed by large drops and aerosols, and ways to reduce it. Their results indicate that the expelled particles take some time to travel more than two meters.
“You need a mask, you need spacing and you need good ventilation so that these particles do not rise inside the building and are safely removed,” said Prof. Said Pedro Malgales de Oliveira. Co-author of the study.
Writing in the Journal of the Proceedings of the Royal Society, de Oliveira and colleagues reported on how they build models that take into account the size of the drops when speaking or coughing from infected individuals, as well as factors including the droplets and so on. It takes time for them to settle down.
The team also looked at the risk of infection, taking into account the viral load of people with covid, and the approximate dose required to produce the infection – the latter was based on a study of a different coronavirus.
The team concluded that it was unsafe for an infected person to live without a mask two meters away from what he was talking or coughing, in both cases there was a risk of infection.
The team added that the total aerosol residue one hour after the infected person called for seconds was more viral mass than after a cough – adding that this caused covid without small spaces and ventilation.
“Speech is a very important point to consider because it produces very fine particles. [than coughing] And these particles, or aerosols, can be suspended for more than an hour, which is enough for the disease, ”de Oliveira said.
But whether people catch Kovid depends on how many aerosols he breathes in – which is influenced by factors including whether the mask is worn, whether the situation is indoors, the level of ventilation and the people involved. Is the distance between.
The team has used their work to develop an airline calculator, called airborne.com, that allows users to detect the risk of being infected indoors by airborne particles alone.
According to the tool, spend one hour in 250 m2 The store – with a maximum capacity of 0 people and ventilation in the area with office fees – is considered to have a%% chance of infecting a person with coronavirus, assuming there are five infected people in the store and no one wearing them. A mask.
If the ventilation is improved so that the air is renewed five times in an hour instead of three hours, this risk can be cut below 2%; The same drop can be obtained if everyone wears a three-ply face mask.
While the risk of infection is only a theoretical estimate and not specific to the UK’s new coronavirus variant, the team said the tool could help users find ways to stay safe in a variety of scenarios.
“The tool is not to get complete risk statistics, but to use it to see how the mitigation strategy affects the risk of infection. It can be used to rank these strategies, for example, “said de Oliveira.
Pro. Catherine Knox, A member of the Scientific Advisory Group for Emergencies and an expert on airborne infections at the University of Leeds, he welcomed the study, but warned that the results were based on a number of assumptions.
“It is likely that the results represent real bad situation circumstances because this model uses very viral high loads as one of the assumptions, and this has a significant impact on the predicted risk,” he said, varying between viral loads and people. During the disease.
