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Is a no-fit respirator on the horizon?
NIOSH seeks advances in N95 design
Imagine a disposable respirator that fits well right out of the box. Or perhaps even a respirator that's inexpensive and requires no annual fit-test.
Such respirators are at least two years away, but major improvements in respirator technology are on the horizon. The National Institute for Occupational Safety and Health (NIOSH) is finalizing a proposed rule that will require manufacturers to design respirators that fit 10 designated facial widths and lengths.
"It would increase the probability that a given mask would fit the workers at a worksite," says Roland BerryAnn, deputy director of NIOSH's National Personal Protective Technology Laboratory. "They are expected to have to do fewer trials of different masks in order to get one to fit. An acceptable fit should be easier to achieve on most workers."
Meanwhile, NIOSH is asking researchers, manufacturers, and users to envision a respirator of the future. The goal: A high level of protection with better fit and no fit-test.
So far, both science and consumer demand have been lacking when it comes to creating the ideal respirator for hospital workers. The disposable filtering face piece respirators, such as the N95, are popular because they're inexpensive, notes Lisa Brosseau, ScD, CIH, associate professor in the School of Public Health, Division of Environmental Health Sciences, at the University of Minnesota in Minneapolis.
While you might be able to walk into a shoe store and pick from a wide range of sizes, respirators usually come in small, medium, and large. "[Consumers] are not willing to pay $100 for the respirator like you might for a pair of shoes. The money isn't there," she says.
Neither is the science. There are actually a lot of facial features that may affect fit such as the size and shape of a person's nose, Brosseau says. During work, the employee is moving and talking, which also affects the fit. Researchers still are trying to determine how to design respirators that fit snugly, can be worn comfortably, and provide adequate protection on different facial types, she says. "We are still pretty much guessing in what makes a respirator fit well over time, during the day and during activities. That's sort of surprising given how advanced we are in other areas," Brosseau says.
NIOSH also defined research gaps in its "action plan," released in 2008. NIOSH will sponsor research in those areas, says BerryAnn. Eventually, NIOSH might find evidence to support a different fit-testing protocol: training, test method, and frequency. "There are more gaps in the science as to what are the factors that affect fit or poor fit, what's the rate at which those dimensions change on a person, and how can you tell if they change," he says. "Once we have some of those answers from research, it will be easier to understand whether a different frequency or methodology may be appropriate."
Meanwhile, manufacturers have tried changes in respirator design, including:
Adhesive edges: If the greatest concern about leakage is around the face seal, what if you created a true seal with adhesive? This technology creates some concerns about comfort, as workers must peel it off their face and the tight fit might make it hot and moist inside the respirator.
FaceSeal Technologies of Toronto makes such a mask, which it calls ViraMask, and touts its low breathing resistance and "built-in evaporative cooling design." Because of the adhesive, the mask comes in just one size, which the company says is a "universal fit." (NIOSH has certified ViraMask as an "escape-only" emergency respirator, which means it can be used to escape from a hazardous work environment but not worn in the workplace.)
Duck bill or fan-folds: Respirators shaped like a duck bill and are said to be more comfortable and provide a better fit than cone-shaped respirators. Other manufacturers have created respirators with folds to make the fit more conforming to the face. For example, Alpha Pro Tech of Salt Lake City touts its "magic arch" as a "one-size-fits-all" design. Brosseau says she isn't aware of any data that compare the folded respirators and their fit characteristics.