Since schools have reopened, children, who are more at risk from air pollution, have been facing high levels of exposure. Air Quality Index (AQI), measured by monitors across the city, show that air quality is often poor. For example, on June 5th, the AQI at BTM Layout was 159, which falls in the ‘unhealthy’ category. At this air quality, children and the elderly, as well as people with lung and heart diseases, may have discomfort breathing.

Anti-pollution masks can help reduce exposure to pollutants and minimise health impacts. Here is an overview of different types of anti-pollutant masks, and tips to pick the right one for yourself and your child.

Types of masks

Anti-pollution masks are broadly categorised into three types, based on their resistance to oil. N (Not oil-resistant) type masks prevent bacteria, spores and particulate matter from getting past the mask. But they do not resist airborne oil particles that include harmful chemicals like benzene and toluene. N type masks can be used continuously for relatively long durations before they have to be cleaned.

R (Resistant to oil) type masks go one step further, and resist oil particles. Finally, P type masks are oil-proof, but they get grimy over a shorter period compared to N type masks. Hence P type masks have to be cleaned more frequently and have shorter lifespans.

N, R and P type masks can keep out particulate matter (PM) that have diameter over 0.3 micron (0.0003 mm). That is, they are effective against  PM10 and PM2.5 – particular matter of diameter lesser than 10 micron and 2.5 micron respectively – except for very minute particulates.

Particulate matter is a mixture of solid and liquid particles suspended in the air, many of which are toxic. They are linked with heart and respiratory diseases, and lung cancer. According to the WHO, PM2.5 exposure is the fifth biggest risk factor for death in India.

Anti-pollution masks come in varieties that can ward off between 95 and 99.97 percent of PM. The extent of PM that a mask can keep out, is indicated by its notation. For example, an N95 mask is an N type mask that can keep out 95 percent of PM.

Cross section of a used filter pad from a P95 mask. Pic: Wikimedia Commons

Which mask should you opt for?

You can opt for N or P type masks depending on whether you are exposed to oil-based particles regularly. If you work in a gas station or chemical factory, for example, you should choose a P type mask since it is resistant to oil. But N type masks are sufficient to counter vehicular pollution, and these don’t need to be cleaned or replaced as often as the P type masks.

So, for the average user, an N type mask that filters 95, 99 or 99.7 percent of PM (N95, N97 and N100 respectively) is ideal. The price of these masks range from around Rs 200 to Rs 2000. The costlier masks tend to have a longer lifespan of 5-6 months compared to the cheaper single-use masks.

It is recommended to buy costlier masks that have longer lifespan. You should make sure that the mask, including its filters, is completely washable. If the filters are not washable, you have to buy extra filters to replace them when they become dirty.

Reusable masks of both N and P types cost nearly the same, but P masks last only 40 hours or one month, which make them less economical and less eco-friendly. R type masks generally have single-use lifespans of about 8 hours only. These masks cost around Rs 1500, whereas P type masks cost around Rs 2000.

Though many Bengalureans are seen using surgical masks, these are neither effective against pollutants nor reusable.

What to look out for while buying masks?

It is important to get masks which are comfortable for you. Users often complain that the masks do not fit comfortably and also make them feel suffocated.

To avoid this:

• Get masks of the right size which do not have leaks, and are not uncomfortable. Some masks can be adjusted with nose clips over the bridge of your nose.
• Get masks with exhalation valves. They make you feel less suffocated, and help remove moisture or fog from the mask. You can get more expensive sports masks that have move valves, to use while exercising or cycling in heavy traffic.

Anti-pollution masks are available at online stores such as Amazon and Flipkart. You can also get them from Apollo pharmacies and some independent drug stores. 3M, Dettol, Vogmask, Repeller and Smart Air are some brands that offer good quality N masks. 3M and Grin Health make quality P masks.