Explained: As coronavirus spreads, can surgical masks protect against infections, pollution?

A girl wears a mask as she walks past a scanning machine monitoring people's temperature following the new coronavirus outbreak from China, at Bandaranaike international airport in Katunayake, Sri Lanka January 24, 2020. (Reuters)

With 26 dead and more than 800 infected so far, China has increased efforts to contain the coronavirus outbreak, cases of which were first reported in mid-December in China’s Wuhan city.

On Tuesday, the US’ Centre for Disease Control (CDC) confirmed a case of coronavirus infection in a man who had recently returned from Wuhan. Now, the virus has spread to Thailand and South Korea too.

As part of measures to contain the outbreak, China has restricted travel for over 35 million of its citizens, just ahead of China’s busiest travel season of the Lunar New Year holiday. People in Wuhan city are being encouraged to wear surgical masks in public.

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In countries such as China and India — especially North India — where the level of pollution is high, surgical masks are also used to protect against pollution.

Can surgical masks help deal with viral infections?

In an advisory, the CDC has recommended precautions for patients under investigation for the novel coronavirus. “Such patients should be asked to wear a surgical mask as soon as they are identified and be evaluated in a private room with the door closed, ideally an airborne infection isolation room if available,” the advisory states.

Significantly, the effectiveness of a mask also depends on whether it is forming a proper seal around the mouth and nose, which is one reason why surgical masks may not be very effective against pollution or viral infections. (Reuters)

According to Dr. PV Sudhakar, dean of Andhra Medical College, Visakhapatnam, while surgical masks help to a degree, masks such as the N95 are better in protecting against “serious infections” such as coronavirus or drug-resistant tuberculosis.

“The surgical mask is like a shield and is two-dimensional, whereas N95 masks are three-dimensional and like a cup,” Sudhakar said. “They fill out all the gaps around the nose and the mouth. N95 masks should especially be used around patients with confirmed viral infections."

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He added that people should not touch the masks with bare hands as it can increase the chances of infection, and should also be careful while disposing them off. This means that the masks should not be thrown on the ground and ideally, should be disposed using a proper biomedical waste disposal system.

Governments, however, cannot supply N95 masks on a mass scale due to their higher costs. This is why most recommendations and advisories around masks are limited to surgical masks.

WHO’s standard recommendations to protect against the novel coronavirus include frequent cleaning of hands with alcohol-based hand rubs or soaps or water, avoiding close contact with anyone who has a fever or cough, and avoiding the consumption of raw or undercooked animal products.

Surgical masks against pollution

To protect against pollution — for instance, the smog over Delhi, which contains dust, pollen, sawdust and certain noxious gases — masks with different types of filters can be chosen, such as N, R or P-type of filters.

The N-type filter offers protection against the inhalation of particulate matter and aerosols that are non-oily in nature. There are three different types of ratings for these three filter types — 95, 99 and 100. This means that an N95 mask will trap 95 per cent of the pollutant particles.

Significantly, the effectiveness of a mask also depends on whether it is forming a proper seal around the mouth and nose, which is one reason why surgical masks may not be very effective against pollution or viral infections.