Commonly Used Cheap Cloth Mask Not Very Effective Against Air Pollution

A new study reveals that the cheap cloth masks, most commonly used in highly polluted areas in Asia and Southeast Asia, could not protect people from the harmful effects of air pollution.

The study, published in the Journal of Exposure & Environmental Epidemiology, showed that inexpensive cloth mask, about 10 to 15 cents each, performed poorly compared to standard hygiene mask known as the N95, which costs about $3 to $4 each.

"This has clear public health risk," said Richard Peltier, an environmental health scientist at the University of Massachusetts Amherst and co-author of the study, in a statement. "Especially if an individual makes personal choices not to avoid high concentration environments because they assume they are protected from these contaminants."

For the study, the researchers conducted a series of experiments on various types of mask: one pleated surgical type, two cloths and one cone-shaped cloth with exhalation flaps. The researches simulated real-world conditions and tested the effectiveness of each mask in filtering out five different synthetic aerosol particle sizes plus three particle sizes of diluted whole diesel exhaust.

The cloth mask with exhaust valves is the best performing one among the tested, with 80 to 90 percent reduction of synthetic particles and about 57 percent of diesel exhaust.

On the other hand, the least expensive cloth mask only removed 39 to 65 percent of standard particles of 30, 100 and 500 nanometers, and 1 and 2.5 micrometers. Plain cloth mask performed better than the others in removing larger particles size, but performed poorly in smaller particles, which are about 2.5 micrometers and often considered to be more harmful than the larger particles due to their ability to penetrate the lungs deeper.

Furthermore, the researchers discovered that effectiveness of the masks to filter air pollution rely on its shape and ability to mold to the face. The cone-shaped mask and snug-fitting surgical mask performed better than the looser-fitting masks.

Their findings are very significant because people who are wearing cloth mask are oftentimes given false sense of security. Because they feel secure and protected by their mask, people sometimes walk freely in highly polluted areas, leading to unwanted health risks.