The Union Health Ministry on July 21 cautioned against the use of N-95 masks with valved respirators, claiming that there are higher chances of the infection spreading from asymptomatic people to uninfected persons through them.

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"N-95 masks come with or without respirators. Evidence shows that even though the mask with valve protects a person from contracting the infection, it can put others at risk. When an asymptomatic person exhales through the N95 mask with a valve, they can spread the infection to others," said the ministry's Officer on Special Duty, during a press conference. "This is an evolving situation and as more evidence comes before us, we will decide whether to conduct a study on it," he added.

On July 20, the Director-General of Health Services (DGHS) had also alluded to the inappropriate use of N-95 masks with valved respirators by the public. "It has been observed that there is inappropriate use of the N-95 mask (particularly with valved respirator) by the public other than designated health workers," the letter addressed to the principal secretaries of health and medical education department of the states stated.

"It is to bring to your knowledge that the use of valved respirator N-95 masks is detrimental to the measures adopted for preventing the spread of coronavirus as they don't prevent the virus from escaping out of the mask," the DGHS said in the letter. "In view of the above, I request you to instruct all concerned to follow the guidelines on the use of face mouth cover and prevent inappropriate use of N-95 masks," the letter read.