N95 masks with valves 'detrimental' to curb the spread of COVID-19: Health Ministry letter to states

Masks like the N95 filters in clean air that the user inhales but the valves release exhaled, contaminated air back into the environment.

In a letter addressed to the letter to all states and union territories, the Director-General of Health Services (DGHS) in the Ministry of Health Dr Rajiv Garg, has warned against the "inappropriate use" of N95 masks, particularly ones that have respiratory valves to help users breathe.

Garg's letter highlights the use of N-95 masks in particular, which are widely used by the public and designated health workers.

"...The use of valved respirator N-95 masks is detrimental to the measures adopted for preventing the spread of coronavirus as it does not prevent the virus from escaping out of the mask," Garg said in the letter.

"In view of the above, I request you to instruct all concerned to follow the use of face/mouth cover and prevent inappropriate use of N-95 masks."

Garg went on to say that states and union territories should encourage the use of homemade cloth masks, which can be made by following guidelines issued by the Health Ministry.

The letter comes amid rising concerns over the airborne nature of the COVID-causing SARS-CoV-2 virus, as well as questions about the effectiveness of valved masks in preventing its spread.

In a recent letter authored by health experts from 32 countries addressed to the World Health Organisation, scientists highlighted that the virus was airborne and superspreaders events take place when many people are confined to poorly-ventilate closed spaces.


Health organisations, including the Centres for Disease Control and Prevention (CDC) and WHO, have recommended the use of facemasks as a simple, cost-effective tool to prevent getting infected by the coronavirus, along with maintaining hand hygiene and social distancing.

"By now, everyone should be wearing some sort of mask whenever they are out and about," said Dr Noe Mateo, an infectious disease specialist for Sanford Health. "So it’s going to feel weird when you go to the barbershop or the supermarket, but this is our new normal until there is a vaccine available for COVID-19."

But it is also necessary to understand the different masks offer different levels of protection.

Valved respirators might not be the best option 

A respirator mask like the N95 removes particles from the air that are breathed through it. It can filter out at least 95 percent of very small (0.3 micron) particles and all types of particles, including bacteria and viruses.

However, according to the CDC, respirators with valves for exhalation shouldn't be used in situations where the surrounding environment needs to be sterile, or germ-free. This is because the exhalation valve allows unfiltered exhaled air to escape into the surrounding air.

Masks with valves are used in industrial settings, where a user needs protection from the environment or when air pollution is high, according to CNBC TV18 report. While these masks filter in clean air that the user inhales, the valves release exhaled contaminated air back into the environment.

In situations where a person wearing an N95 mask with an exhalation valve has the virus but shows no symptoms, they would be releasing the virus into the surrounding air putting others nearby at risk of a COVID-19 infection.

Anupam Sibal, Group Medical Director and Senior Pediatrician at the Apollo Hospitals Group, told Times of India, "If one has COVID-19, the SARS-CoV-2 virus can escape with the unfiltered exhaled air and spread. In many places, such masks have been banned."

Also Read: As lockdown lifts, wearing a face mask could be your only defence against COVID-19: How to pick the right one

Government advisory on face masks

The government had in April issued an advisory on the use of homemade protective cover for face and mouth, asking people to wear it, particularly when they step out of their residences.

The advisory stressed that face covers must be washed and cleaned every day, as instructed.

Cotton cloth, it said, can be used to make this face cover. The colour of the fabric does not matter but one must ensure that the fabric is washed well in boiling water for five minutes, and dried well before making the face cover. Adding salt to this water is recommended, the advisory added.

Also listed were different procedures for making homemade masks, how to ensure it fits the face well with no gaps on either side.

The advisory urges people to wash their hands thoroughly before wearing the face cover, switching to another fresh one as the face cover becomes damp or humid. It also advises never to reuse a cloth mask after single use without cleaning it.

"Never share the face cover with anyone. Every member in a family should have separate face cover,” the advisory stated.

With inputs from wire

Also read: Airborne transmission of the Coronavirus is a possibility claim 239 experts from 32 different countries in a letter to the WHO 

Coronavirus is airborne: Wear mask, stay away from crowded indoor spaces, and other things to keep in mind

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