No good choices: A mask may block out some pollution but have other ill health effects

On November 10, Ved Pal Yadav, a private cab driver in Delhi, experienced breathlessness and a burning sensation in his eyes. “Nothing like this has ever happened to me”, said Pal, who is in his early thirties. The city had been under a thick blanket of smog for a three days. The air quality was categorised as severe, the worst on a scale of six categories set by the Central Pollution Control Board.

Driving past people wearing anti-pollution masks, Yadav thought of buying one for his five-year-old daughter. “But I cannot afford it for all of us in the family,” he said.

Most Delhi residents have resorted to using different kinds of masks to tide over the worst of winter pollution when the air is heavy with high concentrations of harmful pollutants like carbon monoxide, sulphur dioxide, ammonia and particulate matter. But do masks really work and can using a mask cause other health problems?

“Wearing a mask will not prevent you from getting pollution-related diseases,” said Dr Sai Kiran Chaudhari, pulmonologist at Delhi Heart and Lung Institute. “You are breathing that air everywhere and all the time, even while sleeping.”

Delhi residents have been using many kinds of masks to protect themselves from the bad air – cloth masks, surgical masks and more sophisticated masks with pollution filters referred to as N95 and N99 masks. The prefix N denotes non-oil, meaning that the masks filter out non-oil-based particles. The N95 and N99 masks are supposed to block 95% and 99% of PM2.5 – particulate matter of 2.5 micrometres or less in diameter (about 30 times lesser than the width of a human-hair strand). PM2.5 particles are a complex combination of pollutants as dust, pollen, smoke and mist. The tiny particles get easily lodged in the body, and have been linked to cancer and heart attacks. These are harmful at any concentration and are present in a high concentration in Delhi’s air.

Even though these masks are the “go to” protective gear against winter pollution, most health and environmental experts say that the only way to stay safe from the ill effects of air pollution is to prevent pollution itself.

Moreover, they warn that using masks can have several adverse effects, many of which mask users do not know.

How good is your mask?

Cloth masks are only marginally effective in protecting against harmful PM2.5 pollutants, a study from the University of Massachusetts Amherst last year showed. Such masks remove only between 15% and 57% of particle emitted from diesel combustion. The study’s authors said that wearing cloth masks also provided a false sense of security, allowing the wearer to go out in dense pollution even though he or she is not adequately protected.

Meanwhile, masks with filters such as the N95 and N99 masks are also only efficient when worn properly.

“The N95 or N99 mask varieties have been traditionally used in hospitals to prevent tuberculosis and other infections during flu season,” said Dr KK Aggarwal, president of the Indian Medical Association. “They can block particulate matter only if you completely prevent air-leaks, and that is not possible.”

This is because a mask will protect against pollutants only if they fit snugly on a wearer’s face and there are as many facial structures as there are people. Often, well-fitting masks are hard to find and uncomfortable to wear. Even beards and facial hair may be obstructions to a good fit and could let in contaminated air, as some brands specify on their packaging.

While ill-fitting masks let in pollutants, mask that fit too tightly can also be problematic. A person wearing any kind of mask faces breathing resistance as air filters through the device, making the wearer work harder to inhale than he would without the mask. This can have several adverse physiological effects when the mask is worn for long periods of time. Moreover, carbon dioxide that is exhaled can get trapped in the chamber of the mask the re-enter the body each time the mask user inhales. This delivers less oxygen into the body than when the person is not wearing a mask.

“It can lead to oxygen shortage, suffocation, respiration trouble, and heart attacks,” said Dr D Saha, scientist and additional director at the Central Pollution Control Board.

He pointed out that masks are a potential source of bacteria and viruses. “The moisture from exhalation inside the mask, when in constant contact with the 37 degrees Celsius warm human body, becomes ideal place for virus and bacteria to thrive,” he said. This could result in the growth of microbes on masks and aid the spread of airborne diseases like influenza.

User awareness

Even though, health workers often use such masks while dealing with patients of infectious disease, they tend to use them in controlled conditions and replace them at suitable intervals. A resident of Delhi wearing a mask, however, is often not aware of these risks.

For example, traffic policeman Virendra Singh, who was on duty at the intersection of Janpath and Tolstoy Road on a dense fog day in November, wore a disposable N95 mask of a brand approved by the United States National Institute for Occupational Safety and Health. The institute recommends replacing N95 products when soiled, damaged, or when they cause increased breathing resistance. For polluted workplaces, the institute cautions against using the mask for more than eight hours.

“The N95 and N99 are paper or fibre masks and have to be changed every day,” said Chaudhari.

But Singh’s mask had turned a dirty grey at the centre from many days of use. “I will wash it today,” he said, showing no intention of replacing the disposable mask.

And then there are pollutants that even masks with filters cannot keep out. The particulate-specific N95 and N99 offer no protection against gases and vapours like sulphur dioxide, nitrogen dioxide, ozone, and carbon monoxide, that are responsible for conditions such as reduced lung function and lung diseases, irritation of the eyes, asthma, and inflammation of the respiratory tract. “The masks are completely ineffective against gaseous pollutants,” said Aggarwal.

Marketing the mask

At a pharmacy in Central Delhi, Sumeet Arora, a 40-year-old businessman, looked at N95 masks of two companies priced at Rs 295 and Rs 799. With no significant information on the product-packages to aid his buying-decision, he chose the latter with the belief that a costlier product would provide better protection.

Many international companies manufacturing masks for industrial workers are marketing these products as useful tools against particulate and other pollutants. But few specify how these products should be used and when they should be discarded or replaced. One masks manufactured by a US company bears a warning that “misuse may result in sickness or death”, without stating what qualifies as misuse.

In the absence of doctors’ recommendations on anti-pollution masks, the sales staff at pharmacies stores often relay usage-guidelines to buyers, which are inconsistent and arbitrary. At a medical store in Central Delhi’s Khan Market, the salesperson stated the life of a microfibre mask of a popular brand at 200 hours. Two stores away, at another medical shop, a salesperson said the same mask can be used for up to six months.

Sarah Elizabeth Jacob, a media professional, decided to buy a mask after watching news reports on the hazardous levels of pollution in the city. “Wearing a mask means I do not feel breathless but there is nothing to protect my eyes, they burn,” she said.

Aggarwal said such comfort from wearing a mask “is only psychological” and warned against using masks without doctor’s recommendations.