Should more of us wear masks to help slow the spread of the coronavirus?
This matter is to be assessed by a group of advisers from the World Health Organization (WHO).
The group will evaluate the research to find out if the virus can be projected further than previously thought; a study in the United States suggests that coughing can reach 6 m and sneezing up to 8 m.
Panel chair Professor David Heymann told BBC News that the new research could lead to a change in the advice on masks.
The former director of the WHO explained, “WHO is opening its discussion again by examining the new evidence to see whether or not there should be a change in the way it recommends the use of masks. “
What is the current advice?
The WHO recommends that you keep a distance of at least 1 m from anyone who coughs or sneezes to avoid the risk of infection.
He says that people who are sick and have symptoms should wear masks.
But he advises healthy people to only wear them if they are caring for others who are suspected of being infected, or if they cough or sneeze.
He points out that masks are only effective if they are combined with frequent hand washing and used and disposed of properly.
The United Kingdom, as well as other countries, including the United States, advises that social distance should mean staying at least 2 meters apart.
This advice is based on evidence showing that viruses can only be transmitted when transported in drops of liquid.
It is understood that most of these drops will evaporate or fall to the ground near the person who released them.
So what does the new research say?
Researchers at the Massachusetts Institute of Technology (MIT) in Cambridge, USA, have used high-speed cameras and other sensors to accurately assess what happens after a cough or sneeze.
They discovered that an expiration generates a small, fast-moving cloud of gas that can hold liquid droplets of varying sizes – and that the smallest can be transported in the cloud over long distances.
The study – conducted under laboratory conditions – found that coughing can throw fluid up to 6 meters apart and that sneezing, which involves much higher speeds, can reach up to 8 meters.
What are the implications?
The scientist who led the study, Professor Lydia Bourouiba of MIT, told me that she was concerned about the current concept of “safe distances”.
“What we breathe out, cough or sneeze is a cloud of gas that has a strong impulse that can go far, trapping drops of all sizes and transporting them across the room,” she said.
“So having this false idea of security within a meter or two, that the drops will fall to the ground at that distance is not based on what we have quantified, measured and visualized directly. “
Does this change the advice on masks?
According to Professor Bourouiba, in certain situations, particularly indoors in poorly ventilated rooms, wearing masks would reduce the risks.
For example, when faced with an infected person, masks can help divert the flow of their breath and their load of virus from your mouth.
“Fragile masks do not protect against inhalation of the smallest particles in the air because they do not provide filtration,” said Professor Bourouiba.
“But they would potentially deflect the cloud which is emitted with strong momentum to the side rather than forward. “
What do WHO advisers think?
According to Professor Heymann, new research from MIT and other institutions will be evaluated because it suggests that the droplets of coughing and sneezing may be thrown further than expected.
He said that if the evidence was supported, “wearing a mask may be just as effective or more effective than distance.”
But he adds a warning that masks must be worn properly, with a seal on the nose. If they get wet, says Professor Heymann, the particles can pass. People must remove them carefully to prevent their hands from being contaminated.
He adds that masks must be worn consistently.
“It’s not about wearing a mask and then deciding to take it off to smoke a cigarette or eat a meal – it has to be worn full time,” he said.
The panel, known as the Strategic and Technical Advisory Group on Infectious Risks, is expected to hold its next virtual meeting in the coming days.
A spokesperson for Public Health England said there was little evidence of widespread benefit from wearing masks outside of clinical settings.
“Masks must be worn properly, changed frequently, removed properly, safely disposed of and used in combination with good universal hygiene behavior for them to be effective.
“Research also shows that compliance with these recommended behaviors decreases over time when wearing face masks for extended periods. “
Are countries not changing their advice on masks anyway?
Long popular in many Asian countries, the masks are currently being evaluated by the US Centers for Disease Control (CDC).
In Austria, the police now wear them and anyone dealing with the police will also have to wear one. Supermarkets will insist that customers do too.
A once rare sight in Europe is becoming more common, and new WHO advice would accelerate this change.
Follow David on Twitter.