SANCHITA SHARMA

With face masks and respirators more visibly available than firecrackers in many upscale neighbourhood markets this winter, choosing the right one from a glut of options is becoming increasingly difficult.

Do all respirators and masks protect against pollution? Which type would work best for me? Are expensive respirators substantially better than disposable, surgical masks?

They do offer some protection, but a lot more depends on how they fit your face.

Pollution masks and respirators filter liquid and airborne particulate matter, both big and small (PM10 and PM2.5), but do not protect against chemicals, gases, and vapours. If worn properly, respirators protect against vehicle emissions, reducing the risk of respiratory and heart diseases, while also protecting people from infection by blocking droplets and germs (viruses and bacteria).

The N-95 filtering respirators also protect against viruses and other infecting agents but only if they are discarded after single use. People with chronic respiratory, heart disease, infections and other health conditions that make breathing difficult may have trouble breathing through respirators, and must ask their doctor for the best available option.

PARTLY PROTECTIVE, AT BEST

Most commercially available face masks, including internationally certified ones, do not provide adequate protection against particulate matter and black carbon mostly because of poor facial fit, found a study on the effectiveness of a range of this type of face masks in China. The study, published in the BMJ journal, Occupational and Environmental Medicine in April 2018, recommended more attention be given to mask design and providing correct, evidence-based guidance to consumers.

For the China study, the filteration efficacy of nine masks claiming protection against fine particulates(pm2.5) and black carbon were tested by drawing airborne diesel exhaust through the filtering medium. The penetration ranged from 0.26% to 29%, depending on the flow rate and mask material.

Four masks that were tested on volunteers doing sedentary tasks and active tasks had higher average total inward leakage, ranging from 3% to 68% in the sedentary tests and from 7% to 66% in the active tests. Only one mask type tested had an average total inward leakage of less than 10% under both test conditions.

FIT MATTERS MOST

Masks and respirators have to be adjusted to fit snugly and over the nose and mouth to stop polluted air leaking in. The effectiveness of masks, including those made using highly-efficient particle filtering material, is usually much lower than certified because of