New research has highlighted the importance of wearing masks to prevent the spread of coronavirus, corroborating the UAE’s decision to make them mandatory.
Scientists found face coverings prevented the release of virus-containing droplets and tiny airborne particles responsible for the pathogen’s spread.
The analysis laid bare the risk posed by such aerosols, which are less than five micrometres (a 200th of a millimetre) in diameter.
They are released into the air when people breathe or speak, and can remain suspended for hours in contrast to larger droplets, which typically fall to surfaces within seconds.
Experts said “a large proportion” of coronavirus infections appeared to be caused by the release of these aerosols by those who were not yet symptomatic.
“Evidence suggests that SARS-CoV-2 [the new coronavirus] is silently spreading in aerosols exhaled by highly contagious infected individuals with no symptoms,” the study said.
“Owing to their smaller size, aerosols may lead to higher severity of Covid-19 because virus-containing aerosols penetrate more deeply into the lungs.”
The research paper was co-authored by scientists from the University of California San Diego in the United States and the National Sun Yat-Sen University in Taiwan.
Entitled Reducing transmission of SARS-CoV-2, it was published in the journal Science on May 27.
As part of the paper, academics reviewed 15 existing studies on the pandemic and the nature of the outbreak’s transmission.
They highlighted research from a hospital in Wuhan, China, the city where the virus began, which indicated aerosols could travel more than six feet.
That study found that when a person coughs or sneezes hard, droplets can be spread more than 20ft and “thousands” of aerosols can travel further still.
Other research also indicated that outdoors, the virus could spread even larger distances on breezes, although this was found to be less of a risk due to aerosols being diluted.
Professor Chia Wang, of National Sun Yat-Sen University, Taiwan, one of the study’s authors, said social distancing rules implemented by governments were mostly based on the spread of droplets and took less account of the risks of aerosols.
“When someone is infected by the virus, when they emit aerosols, these aerosols can contain the virus,” she said.
“Wearing a mask, both by an affected patient and a healthy, unaffected person, should effectively block the transmission of the virus-containing aerosols.”
As countries around the world attempt to reduce Covid-19 restrictions and resume normal activity, researchers argued that widespread testing - so infected individuals could be identified and isolated - as well as “universal” mask wearing, was required.
In the UAE, all members of the public are required to wear masks outside the home, with those failing to adhere to the measure risking a Dh3,000 fine.
Some exceptions have been allowed, however, with officials in Dubai saying those eating or drinking, who were alone or doing strenuous exercise, did not have to observe the rule.
Meanwhile, other countries have chosen to ignore making the wearing of masks mandatory entirely.
Dr Andrew Freedman, an infectious diseases specialist at the School of Medicine at Cardiff University in the UK, said the benefit was probably only greater in certain circumstances.
“It’s really indoors, because the risk is much higher,” he said. “[For example on] public transport – anywhere where it’s very difficult to maintain the two-metre or one-metre distancing.
“My feeling is outdoors they’re unnecessary. There’ve been some concerns they could have a negative effect – they might give people a false sense of security.
“They might think if they wear a mask, they don’t have to keep their distance, but none of this is proven. On balance, they probably are useful.”
Prof Wang estimated that at the peak of the outbreak in Taiwan, around 90 per cent of people on the street wore masks, which were mandatory in many indoor spaces too.
The study also credited mask-wearing with limiting outbreaks in Hong Kong, South Korea and Singapore.
“Universal mask wearing will certainly help to prevent the transmission of Covid-19,” she said.
