Safety Spotlight
Tips for Optimum Mask Efficacy A
Although the general public has been asked to wear masks for nearly a year, a number of misconceptions about proper use remain. Many of us may be wearing masks incorrectly, unknowingly reducing their efficacy and putting ourselves and those around us at greater risk of contracting and spreading COVID-19. Furthermore, we’ve learned a lot about mask usage in the past year. That’s why the Center for Construction Research and Training (CPWR) invited Maryann D'Alessandro, director of the National Personal Protective Technology Laboratory (NPPTL), a research center of the National Institute for Occupational Safety and Health (NIOSH), to present a webinar sharing best practices and correcting common misconceptions. Here are 11 insights D'Alessandro shared. 1. Who has regulatory authority over respirators in U.S. occupational settings? This depends. Authorities include NIOSH, the Occupational Health and Safety Administration (OSHA) and the U.S. Food and Drug Administration (FDA). NIOSH certifies respirators, while OSHA oversees workplace compliance. The FDA, however, certifies medical devices and has additional requirements for N95 masks used in healthcare settings. 2. As an employer, what do I need to do to comply with OSHA’s respirator regulations? Proper respirator use in the workplace is outlined in OSHA’s 29 CFR 1910.134, which mandates medical evaluation, formal training and fit testing. D'Alessandro recommends reviewing the variety of resources available to guide compliance efforts. “Construction is already familiar with fit testing because there are many exposures where employees are required to wear respirators in the workplace,” D'Alessandro said. She also recommends conducting a user seal test when a user first puts on a respirator to minimize face seal leakage and increase user confidence, though this does not replace a fit test.
8 // February 2021
“Respirators used in the general public are not subject to the same requirements as those in the workplace,” D'Alessandro added. 3. Am I wearing my mask properly? For a respirator to be effective, it must be put on correctly, worn throughout the exposure, and fit snugly against the user’s face to ensure there are no gaps between the skin and the respirator seal. She points out the possibility of facial hair compromising the respirator’s seal, sharing a graphic of various appropriate and interfering facial hair styles that went viral on social media. For example, soul patches and Zorro mustaches are unlikely to interfere with a respirator’s seal, whereas mutton chops and Fu Manchu mustaches will impact the seal and reduce the protection received by the wearer. See the graphic on this page. 4. Do masks protect me, the people around me, or both? This also depends on the type of mask used, D'Alessandro said. Masks offering source control protect others, while respiratory protection protects the wearer. “There is some evidence,” D'Alessandro said, “that devices worn for source control provide some protection for wearers as well, though they are not equivalent to respiratory protection devices.” 5. How effective are different types of respiratory devices? “Respirators and face masks have a wide range of filter efficiencies,” D'Alessandro said. A device rated P100 has a filter efficiency greater than 99.98 percent; an N95 mask, greater than 98.8 percent; an FDA surgical mask ranges from 12 to 98 percent; cloth masks range from 10 to 26 percent. 6. Do you have any recommendations for selecting a more effective cloth mask? Choose a mask with two or more layers of washable, breathable fabric. Be sure the mask completely covers your nose and mouth, and fits snugly against the sides of
your face. “You see a lot of people out there who have their nose exposed,” D'Alessandro said. “The nose is the entry portal for many viruses, so it’s very important to cover your nose and your mouth.” For people who wear glasses, a mask that fits closely over one’s nose or a mask that has a nose wire can help to limit fogging. D'Alessandro also said to avoid masks intended for healthcare workers, such as N95 respirators and surgical masks. NIOSH is involved in several initiatives to address gaps in non-occupational respiratory protection and source control, D'Alessandro said. She added that the American Society for Testing and Materials (ASTM) is working on a test method to determine filter efficiency for cloth masks. 7. Can I use a respirator with an exhalation valve? “The current Centers for Disease Control (CDC) guidance is that you shouldn’t use a respirator with an exhalation valve,” D'Alessandro said. However, NIOSH published a report in December 2020 (www. cdc.gov/niosh/docs/2021-107/default. html) sharing recent findings that may contradict past guidance. “Our suspicion was that respirators with face valves would provide source control relatively equivalent to cloth face coverings and surgical masks because you don’t have the gaps on the side that you often have with cloth masks. That is what we found in our technical report, so we are working to update the guidance.” Furthermore, she added that some manufacturers of respirators with exhalation valves are working on designated accessories to cover the valve. Some elastomeric respirators (EHMRs) also have exhalation valve covers, and some manufacturers of EHMRs are filtering exhaled breath coming out of the valves. 8. What about gaiters and face shields? “There have been a few studies out there on gaiters that have shown they are not a good product to wear,” D'Alessandro said. “But other studies show that if you have at least two layers, like if you fold a gaiter to make it
