Wearing face masks helps “significantly reduce” airborne transmission of coronavirus to other people in cities, research has found.
Scientists at Texas A&M University examined the person-to-person spread of Covid-19 as part of a study into preventative procedures and trends in New York City, Italy and the pandemic's epicentre of Wuhan in China.
Researchers found that wearing a mask was key to preventing infected droplets reaching healthy people, and also those with the virus from spreading it.
The study - titled Identifying airborne transmissions as the dominant route for the spread of Covid-19 - was published in the journal Proceedings of the National Academy of Sciences.
Airborne transmission between people occurs through droplets in coughs and sneezes, and even talking.
In New York City, scientists calculated the number of infections was reduced by more than 66,000 over about three weeks, or around three per cent daily, in April - after face masks became a mandatory - following stay-at-home and social distancing orders.
New Yorkers have been told they must “wear a face covering when outside their home if they cannot maintain at least six feet from others”.
But in the rest of the US infections continued to rise over the same period, research data shows.
Further examination of the infection rates in northern Italy earlier that month, the former European centre of the outbreak, found infections had been reduced by more than 78,000 over a month as people were mandated to wear masks in shops and on public transport.
In London, more than 3,000 extra British Transport Police officers and railways staff have been deployed to ensure travellers on public transport obey new rules to wear masks that were brought in only this week.
Passengers can be fined £100 or refused access to public transport for non-compliance.
The true total of coronavirus-related deaths in the UK is believed to have passed 53,000 - far higher than Department of Health data shows - according to the Office for National Statistics.
Lead study author Renyi Zhang, distinguished professor of atmospheric sciences at Texas A&M, said that in China mandated face-coverings helped manage the outbreak as people were already used to wearing masks in the battle to protect themselves against air pollution.
He said: “Our results clearly show that airborne transmission via respiratory aerosols represents the dominant route for the spread of Covid-19.
"By analysing the pandemic trends without face-covering using the statistical method and by projecting the trend, we calculated that over 66,000 infections were prevented by using a face mask in little over a month in New York City.
“We conclude that wearing a face mask in public corresponds to the most effective means to prevent inter-human transmission.
"This inexpensive practice, in conjunction with social distancing and other procedures, is the most likely opportunity to stop the Covid-19 pandemic.”
