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) in Pittsburgh 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, in a "No-Fit" workshop to be held on Nov. 8, 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 facepiece 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 may 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.
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Fit test is another part of preparedness Yale program teaches HCWs about PPE While hospitals around the country are scrambling to reduce the number of employees receiving an annual fit-test, Yale-New Haven (CT) Hospital is beefing up its program as a part of pandemic influenza preparedness. "You can argue about the utility of a yearly fit test," says Mark Russi, MD, MPH, the hospital's director of occupational health and associate professor of medicine and public health at Yale University School of Medicine. "But there's one thing you can generally get people to agree on: If you're required to follow a detailed multistep process, and you have recently been trained, you're more likely to do it well." Yale's program focuses on donning and doffing all personal protective equipment not just respirators. And it covers most employees with patient contact. After all, in the outbreak of severe acute respiratory syndrome (SARS) in Toronto in 2003, some health care workers became infected despite wearing N95 respirators. Some safety experts later suggested that breaks in infection control may have occurred during use of the personal protective equipment or when it was donned or doffed. "The small errors that we make are a lot more consequential if we're dealing with pandemic influenza or SARS," says Russi. Yale-New Haven Hospital employees are required to complete an online module on PPE every year. They also will participate in an annual pandemic drill, which includes the proper method of donning and doffing PPE. As a part of the program, employees receive an annual fit-test from nurses who have been trained to conduct "just-in-time" fit-testing, he says. Yale-New Haven Hospital conducted a pilot project in conjunction with the Yale Office of Emergency Preparedness and the U.S. Northern Command's National Center for Integrated Civilian/Military Domestic Disaster Medical Response. "We need to get everybody in a position where they can safely don and doff all the personal protective equipment," says Russi. "It isn't something that's necessarily intuitive. "We're taking care of our yearly requirement to do fit-testing by drilling on a regular basis. At the same time, we build an infrastructure for 'just-in-time' fit testing and PPE training that can be activated in the event of pandemic influenza or another highly transmissible pathogen spread via the airborne or droplet route." The use of the annual module has been effective as an education tool, he says. "People donned and doffed much more effectively with fewer errors after training," he 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 February. 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.
(Editor's note: The No-Fit Workshop will be held at the Embassy Suites Airport in Pittsburgh on Nov. 8, 2008. More information is available at http://cpheo.sph.umn.edu/mcohs/)
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