Air Pollution Masks: It’s Fit and Filtration that Matter
H appily, more Mongolians seem to be wearing air pollution masks this year than last year. That is encouraging because exposure to air pollutionis a significant cause of early death through a growing list of ways including miscarriages, pneumonia, chronic obstructive pulmonary disease, asthma, heart attack, stroke, and lung cancer.
H owever, it’s concerning many Mongolians believe they are protected by masks that likely offer little protection. When it comes to air pollution masks, it’s fit and filtration that matter.
Leakage of particles between the mask and the face has been shown to be the main source of particles inhaled particles for people wearing the type of respirator masks worn in Mongolia. Preventing leakage is so important that the US Occupational Safety and Health Administration (OSHA) requires an annual fit test of workers who wear masks in the workplace to confirm that a mask forms a tight seal on the wearer’s face. Many of the masks that people here wear have visible gaps between the face and the mask. Others wear masks only over their mouth. Beware there is little air filtration if the mask doesn’t cover your nose and mouth and seal. Air must be sucked through the filter material not around the mask edges. To prevent leakage masks must have straps that pull the mask snuggly so that it seals tightly against the face. This requires straps that go around the head instead of looping over the ears. There are no masks held against the face with loops around the ears that have passed the US National Institute for Occupational Safety and Health (NIOSH) certification process.
Filtration is critically important. Masks work primarily as mechanical and electrostatic filters removing particles from air by intercepting and impacting the particles in the air into the surface of the mask during inhalation. The fine particulate air pollution particles 2.5 micrometer (0.0025 mm) and smaller (PM2.5) are most hazardous to health so consequently the pore size of the masks must be very small. Masks which satisfy the European FFP2 filtration standard must filter at least 94 percent of particles measuring up to 0.0006 mm while the masks meeting the American N95 filtration standard must filter 95 percent of particles 0.0003 mm or larger in diameter. To give one a sense of how small 0.0003 mm is, the lower limit of visibility of the human eye is 0.04 mm. That means you would need a microscope with 133 times magnification just to identify a 0.0003 mm pore in the mask. A 0.0003 mm pore is about three percent the diameter of a human hair, about the size of a single bacteria. Cloth and foam masks have holes that typically far exceed this distance and consequently provide little filtration. A study from Peltier Aerosol lab at the University of Massachusetts last year found that cloth masks were only marginally beneficial in protecting individuals from PM2.5 particles. Surprisingly, disposable surgical masks were more effective than cloth masks in reducing particulate exposure.
You may have noticed that some masks have small plastic objects that protrude on front of the mask. These are exhalation valves that open slightly when one exhales and then close when one breaths in. They are designed to dissipate the moisture that builds up in space behind the mask and decrease exhalation resistance, making the mask more comfortable to wear.
How long should you use one mask before discarding it? It’s an important question since these respirators act as filters and plug with use over time increasing breathing resistance. NIOSH indicates that unless the respirator manufacturer specifies duration of use you can wear a mask until it is soiled, damaged or causes noticeably increased breathing resistance. However, some masks are intentionally colored to hide the appearance of the particles they accumulate. How can a user see if their mask is soiled when it is dark to begin with?
A study published last year in the Central Asian Journal of Medical Sciences showed that Mongolian women are reluctant to wear masks because it impacts their appearance and messes up their makeup.
So, there has been a recent trend to make the masks more attractive with multiple colors and decorative patterns to encourage their use. Encouraging mask usage is desirable. But the NIOSH warns against using masks that have been altered to make them more fashionable by adding fabric or decorations because doing so can pose health risks and voids their NIOSH certification. So, when selecting a mask, be careful not to lose focus on fit and filtration which matter far more than fashion.
How can you tell if a mask really meets any fit and filtration standards? Without testing from a reputable independent lab, you can’t be sure. A cooperative study in Mongolia between Green Chemistry, Mongolian National University of Medical Sciences, and School of Public Health compared 18 types of air pollution masks in their lab. They reported that 3M paper masks had the highest PM2.5 filtration. Companies must submit their masks to NIOSH for testing prior to selling them in the US, but there is no such requirement here in Mongolia.
Beware of package labeling. In some cases, respirators are labeled with “N95” or the NIOSH logo, but they haven’t actually gone through the NIOSH certification process or have been rejected. These masks are sold for less money than certified masks to cost-conscious consumers. But you can filter out the facts regarding NIOSH certification. This information is available by checking NIOSH-Approved Particulate Filtering Facepiece Respirators at https:// www.cdc.gov/niosh/npptl/topics/ respirators/disp_part/default.html.
Finally, you may not be aware, but it is possible to know the air quality in Ulaanbaatar on a given day. This information is available on the Air Quality Index (AQICN) website at http://aqicn.org. AQICN has a series of sensors distributed throughout the city that provide PM2.5 particle count information that is updated many times throughout the day. It also has a descriptive scale for the air pollution level associated the quantitative measurements, the level’s health implications and some cautionary statements. Air quality measurements are also available at http://agaar.mn/and they also have a smartphone app.
The winter air pollution can be formidable here but there is one thing you can do about it: Wear a mask that fits and filters!
The author of this article is an American physician with a master’s degree in mechanical engineering. He
is a Deseret International Charities volunteer at the Mongolian National University of Medical Sciences where he serves as an English editor for the Central Asian Journal of Medical Sciences. He has no financial conflict of
interest related to this article.