Wearing a mask reduces chance of transmitting COVID-19

According to a new British study wearing a mask dramatically decreases the likelihood of transmitting COVID-19.

Shoppers in central Brisbane yesterday, Picture: Dan Peled

Wearing a mask dramatically decreases the likelihood of transmitting COVID-19, according to a British study which found they blocked 99.9 per cent of droplets released when talking or coughing.

The study published in the journal Royal Society Open Sciencefound that both surgical and handmade cloth masks were effective.

The researchers from the University of Edinburgh found that a person standing 2m away from someone coughing without a mask would be exposed to over 10,000 times more respiratory droplets than someone standing only half a metre away wearing a basic single-layer mask.

The researchers analysed the spread of droplets when a person is talking or coughing using UV light imaging, and also via microscopy. They used a manikin to simulate the speaking or coughing initially before testing with human volunteers.

“When the manikin was fitted with either surgical or handmade masks, not one droplet was found to fall through the lower edge of the fields of view in either speaking or coughing simulations,” the study found.

“With both mask types, small numbers of droplets (up to seven) were seen at various distances from the manikin, but these values were four and five orders of magnitude lower than those observed without a mask for speaking and coughing, respectively.”

The study used four male and two female volunteers, aged between 30 and 45, to either read a sample script for three minutes or cough for one minute. For each test, a glass slide was placed in front of the individual’s mouth. The scientists then used a microscope to count the droplets generated by the subject.

“For all subjects, we did not find a single droplet when a mask was worn,” the authors said.

The study did not measure the effectiveness of masks on the airborne way of transmission.

“The data does not allow us to draw conclusions on the risks of virus transmission through aerosol inhalation,” the study’s authors said. “Assuming that SARS-CoV-2 virus transmission through aerosol is small compared to through large droplets, these results suggest that physical distancing can be reduced with the use of face coverings.”

The authors said the study demonstrated that social distancing measures could be relaxed if people were wearing masks.