N-95 masks protect users, not those around: Experts

Using N-95 masks with valves is recommended when pollution levels are high because they do not allow carbon dioxide to accumulate inside the face cover, experts said.

People using N-95 masks with respiratory valves may be protecting themselves, but those around them could be at high risk of contracting an infection, according to experts who recommend the use of face covers without valves in a viral outbreak such as the coronavirus disease (Covid-19) pandemic.

While all masks filter the air users are inhaling, the ones without valves also trap most of the germs coming out with exhalation, protecting people around those wearing them. (Bloomberg Photo)

Using N-95 masks with valves is recommended when pollution levels are high because they do not allow carbon dioxide to accumulate inside the face cover, experts said. But the same valve — used for exhalation — could act as an easy passage for germs and endanger those in close proximity if the user has an infection.

“If you’re using N-95 masks, use the ones without a valve,” said GC Khilnani, a member of the Delhi chief minister’s advisory committee on Covid-19 preparedness and the chairman of PSRI Hospital in New Delhi.

While all masks filter the air users are inhaling, the ones without valves also trap most of the germs coming out with exhalation, protecting people around those wearing them.

The Union health ministry has been issuing regular advisories, asking people to avoid wearing N-95 masks, which are used as part of personal protection equipment (PPE) kit for health care and other frontline workers dealing with Covid-19 cases.

Harsh Mahajan, the owner of Mahajan Imaging, a diagnostic centre, said N-95 masks should be prohibited even for health care workers. “In fact, in Covid times, N-95 masks with valve should be banned as these are meant to be used during high pollution levels...the valve meant to breathe out air will also let germs (viruses and bacteria) pass, making it unsafe for others in close proximity. The purpose of wearing a mask to protect others will get defeated in the time of Covid-19,” he said.

Khilnani said it is important to wear a mask in way that it covers the face snugly from the upper part of the nose to the chin. “If you use washable masks, wash, dry and reuse after five days...Surgical masks should be disposed of after every use,” he said.

Surgical masks are recommended by the World Health Organization (WHO) for health care and sanitation workers who are not directly involved in dealing with Covid-19 patients. These masks create a barrier around the nose and the mouth, but such face covers should be discarded after each use. Another option is a homemade face cover (preferably made of cotton fabric) that can be reused after washing.

SK Chhabra, a senior pulmonologist at Primus Hospital in New Delhi, said: “For healthy persons stepping out, face covers should provide some protection as these will stop exposure to bigger droplets. However, the use of handkerchiefs or stoles should be avoided as there will be too many leak points. These will only provide psychological relief that the person is aware about the need for precaution.”

Only cotton should be used to make masks, he said. “Apart from not being virus-friendly, cotton is also a breathable fabric that doesn’t trap heat and humidity so much. Chances of the face cover not getting wet easily are higher in cotton-made covers. Once the mask gets wet you have to replace it; otherwise, it is not effective. Nylon ones will serve no purpose at all,” Chhabra added.

Cotton-made face covers are recommended for healthy people or those with flu-like symptoms who are stepping out of their houses.

However face masks don’t provide 100% protection and should be used while maintaining hand hygiene, cough etiquettes and physical distancing by staying at least six feet (2 metres approximately) away from others, according to experts. Gloves too are important, and need to be regularly disinfected with a sanitizer even while a user is wearing them.

“One should properly discard the gloves after use. Gloves are usually disposable and must be discarded after single use,” said Srikant Sharma, a senior consultant at the department of medicine, Moolchand Hospital.