Why can’t we have better respirator fit?
NIOSH fit criteria are a year away
Why can’t N95 filtering facepiece respirators fit better? Amid the turmoil over annual fit-testing, employee health professionals are asking for better products and product information.
It may be a while before they get them.
The National Institute for Occupational Safety and Health (NIOSH) is working on new certification requirements that would require manufacturers to make better-fitting respirators. The changes will not be available for at least a year.
"We should be able to get access to information that we can use in purchasing decisions," notes James Garb, MD, director of occupational health and safety at Baystate Health System in Springfield, MA, echoing the sentiments of many.
Yet for now, fit-testing remains the only way for hospitals to know whether they have chosen a well-fitting or poorly fitting respirator. If most of your employees fail the fit-test, you haven’t selected a good model for your work force.
"It’s just a consumer nightmare," says James Johnson, PhD, CIH, QEP, chemical and biological safety section leader at Lawrence Livermore National Laboratory in Livermore, CA.
Johnson is chair of the ANSI Z-88 secretariat, which sets voluntary respirator standards.
Customers can ask for information about respirator fit, but they may not be able to get it because manufacturers don’t necessarily test their models, he continues, and they don’t have to follow a standard protocol in testing, so there’s no way to compare their test results with those of another company.
NIOSH eliminated fit-testing as part of its certification criteria for filtering facepiece respirators in 1995, placing a focus, instead, on testing the filtration properties rather than the fit. Fit-testing of individual employees would ensure proper fit, NIOSH said. That and other changes influenced the manufacture of less expensive respirators, government officials said at the time.
"There’s no requirement at this point in the certification process for the respirator to fit a person," Johnson explains. "Since filtering facepieces have no requirement for fit in the certification process, many manufacturers don’t worry about it anymore," he adds.
Today, there are N95 respirator models that hardly fit anyone, studies show.
Fit-tests and fit characteristics work together to ensure that a respirator actually provides the protection it is designed to have, explains Chris Coffey, PhD, chief of the laboratory research branch of the NIOSH Division of Respiratory Disease Studies in Morgantown, WV.
Fit-tests are important to ensure that a specific model and size fits the unique facial structure of an individual, he says, but adds, "Fit-tests are not infallible. There are going to be people who pass the fit-test in error."
Respirators also need to have good leakage characteristics, Coffey notes. "Not every respirator is going to fit everybody. But you can’t just rely on a fit-test to keep screening out respirators that don’t fit a large portion of the population."
In fact, different models even from the same company can have a dramatically different performance. In a study of 18 models, he found three that fit performed well out of the box, even without fit-testing.
Yet the performance of the other respirators dropped off sharply. The highest pass rate for any respirator using a qualitative fit-test method (Bitrex or saccharin) was 55%. With one respirator model, only three of 24 people tested with Bitrex passed and no one passed the saccharin test. Five respirator models failed all fit-tests using the Portacount.1
Quantitative fit-testing resulted in a better fit than did qualitative fit-tests. Although fit-testing improved performance, it did not guarantee adequate protection, the study found.
"The findings of this study demonstrate that, with the current state of fit-testing, it may be of more benefit to the user to wear a respirator model with good-fitting characteristics without fit-testing than to wear a respirator model with poor-fitting characteristics after passing a fit-test," the authors concluded.
"The performance of poor-fitting respirator models is improved to a greater extent with fit-testing than respirator models with generally good-fitting characteristics. The highest level of protection is provided by passing a fit-test with a respirator model that has good-fitting characteristics," they wrote.
Consumers can ask manufacturers for their own fit-testing data, respirator experts say.
"We do extensive research on fit in designing the respirators to fit different people and ranges of people," says Craig Colton, CIH, of 3M Co. in St. Paul, MN.
NIOSH has relied on fit-testing to weed out poorly fitting respirators. Yet a 2001 study by the Bureau of Labor Statistics and NIOSH found that only 57% of employers conducted fit-testing on N95s and other respirator types that require a tight face seal.2
NIOSH now is working on criteria for "total inward leakage" — tests that encompass all components of the respirator, including the filtration protection, the face seal, and any exhalation valve.
"That type of quantitative performance requirement does not currently exist. Our goal is to define that requirement and implement it as a part of certification testing," says Les Boord, acting director of the National Personal Protective Technology Laboratory of NIOSH in Pittsburgh.
Respirators that fail to meet the "recognized performance benchmark" will not receive NIOSH certification — which means they won’t meet Occupational Safety and Health Administration (OSHA) standards for protecting employees.
In an equally important move, NIOSH is redefining the range of faces that a respirator must fit. Currently, respirator fit is measured against a sample population that was designed in the late 1960s to be representative of the U.S. work force.
Today’s work force differs greatly; immigration and social change has led to racial and ethnic diversity, and changes in lifestyle have meant more obese and overweight workers.
"We will implement this current contemporary fit-test panel appropriate for the American population. That will become the sizing instrument that’s used for respirator performance," says Heinz Ahlers, acting chief of the NIOSH respirator branch in Pittsburgh.
The change in the fit-test panel alone should influence the manufacture of better-fitting respirators, Johnson adds. In fact, models may need to be available in more than three sizes to fit the range of workers, he says. "[This] is something that needs to be done."
New standards for better-performing respirators will not alter the need for annual fit-testing, respirator experts say. For example, as people age, their facial structure changes, and they may need a different size or model of respirator.
Other changes can be subtle, Ahlers says. "If you decide in the course of the year that it would be a little more comfortable if the straps were looser, or you get a little worried about exposures and make the straps tighter, either one of those decisions can result in a poorly fitting respirator."
Because different respirator styles could have slightly different user seal checks, wearers should be reminded how to do the seal check correctly. "[Annual fit-testing] familiarizes the worker with the mask, it demonstrates and provides data that the mask fits. It also provides the opportunity for hands-on training," he says.
Manufacturers concur that fit-testing is necessary. "We support annual fit-testing, the frequency required by OSHA standard, if you’re going to ensure correct and safe use," notes Colton.
Technology and fit performance might evolve in the future to allow less frequent fit-tests. But for now, annual fit-testing is an essential part of proper protection, Ahlers says.
If hospitals feel overwhelmed by that, they should reevaluate how many employees are designated to wear respirators, he advises.
"Current NIOSH respirator program recommendations are made for workers who are at risk," says Ahlers.
"Public health recommendations may be made by hospitals on the basis of protecting all persons in a hospital in the event they may be exposed to some risk." That involves a different scope, he adds.
References
1. Coffey CC, Lawrence RB, Campbell DL, et al. Fitting characteristics of eighteen N95 filtering-facepiece respirators. Journal of Occupational and Environmental Hygiene 2004; 1:262-271.
2. National Institute for Occupational Safety and Health, Bureau of Labor Statistics. Respirator Usage in Private Sector Firms, 2001. Morgantown, WV; 2003. Web site: www.cdc.gov/niosh/docs/respsurv/pdfs/respsurv.
Why cant N95 filtering facepiece respirators fit better? Amid the turmoil over annual fit-testing, employee health professionals are asking for better products and product information. It may be a while before they get them.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content. TESTING
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