NIOSH: No flaws found in 3M 8000 respirators
Cal-OSHA still worries about poor fit of N95s
The 3M 8000 respirator recalled by the state of California as poorly fitting has passed muster in a review by the National Institute for Occupational Safety and Health (NIOSH). And Cal-OSHA, the state's occupational safety agency, is none too happy about it.
The case once again highlights the quandary of fit posed by N95 respirators. NIOSH has proposed a "Total Inward Leakage" rule that would set tough new criteria for fit for all filtering facepiece respirators. But California officials say hospitals and other employers may still have a hard time purchasing and stockpiling respirators that will fit most of their workforce.
Meanwhile, they aren't satisfied by a NIOSH report that concluded that any fit-test problems with the 3M 8000 didn't result from "any defect in the units' characteristics on which the product was certified." In two NIOSH fit-test evaluations, the respirator was successfully fit-tested on 55% and 62.5% of test subjects, using quantitative fit-testing.
That placed the 3M 8000 "within the expected performance levels for [filtering facepiece respirators] of similar construction," the report concluded. The 3M 8000 is a "one-size-fits-all" respirator with a headband strap that attaches at a single midpoint of the mask.
"While that's not optimal fitting characteristics, there is a segment of the population that can be fit-tested and presumably use it successfully," says Roland Berry Ann, deputy director of the NIOSH National Personal Protective Technology Laboratory in Pittsburgh. The proposed NIOSH rule would require a pass-rate of at least 74% for a 35-person panel of different facial dimensions.
Cal-OSHA officials say the NIOSH report still doesn't demonstrate that the 3M 8000 could be successfully fit-tested in a workplace. Problems with the respirator came to light when Kaiser Permanente attempted to fit-test employees with the stockpiled respirators and found that all of the first 15 employees tested failed their fit-tests.
"The study is basically calling acceptable a situation we don't really think is acceptable," says Cal-OSHA chief Len Welsh, MS, JD. "We would like to see a test procedure that more closely mirrors the real world."
Berry Ann notes that the NIOSH evaluation was designed specifically to look for defects. NIOSH does not currently have a fit requirement for N95 filtering facepiece respirators, although it is developing new fit criteria in a proposed Total Inward Leakage rule.
Testing allows for failures
Many hospitals use a qualitative fit-test method with Bittrex, a bitter-tasting agent, and it is this method that led to a higher failure rate in California. As employers do the maneuvers required for the fit-test procedure, a momentary break in the seal will cause them to taste or smell the Bittrex and fail the fit test.
Quantitative fit-testing produces an overall pass-fail score, and a respirator can still pass even if the seal is momentarily breached. The Kaiser failures occurred with qualitative fit-tests. When a 3M representative repeated fit-tests with a quantitative method, 40% passed.
While NIOSH got a somewhat higher pass rate when it tested two lots of respirators, the agency allowed three fit-test attempts per person tested. Employers generally test each person once per respirator model or size.
"If you wanted people to repeat a fit-test three times and the likelihood they would pass is only 40%, that's an enormous investment of time on the employer's end," says Deborah Gold, MPH, CIH, senior safety engineer in the research and standards health unit at Cal-OSHA in Oakland.
The NIOSH evaluation of the 3M 8000 involved 40 test subjects who represented all the facial sizes of the agency's new test panel. However, in some size categories, or cells, only one or two people were tested.
That makes it impossible for an employer to know who best fits this "one-size-fits-all" respirator, notes Gold. "[The test panel] needs to be large enough so that you can get statistical significance in the cells represented by the respirator," she says.
Tougher tests for respirators?
In short, Cal-OSHA is not satisfied that the 3M 8000 has demonstrated adequate fit characteristics for the health care workforce. Based on this real-life circumstance, they want NIOSH to alter its proposed Total Inward Leakage (TIL) rule.
"[T]he TIL-style results [of the NIOSH tests of the 3M 8000] did not well represent the performance of the respirator in real-world situations," Cal-OSHA said in written comments to NIOSH.
NIOSH should require manufacturers to test more than 35 people to gain certification for their respirators, and the detailed results should be available to purchasers so they know which facial dimensions the respirator is most likely to fit, Cal-OSHA said.
"If this respirator had been slightly better, maybe it would have passed the TIL and we would still have had no indication of who it fit because we don't know how the fit is distributed among the matrix [of facial dimensions]," Gold says. "You need to have a sample that's of sufficient size to know reliably who it's going to fit."
Testing more people might mean manufacturers pay more to receive certification, says Gold. But it could reduce costs for employers because they would need to conduct fewer fit-tests to find respirators for their workers, she says.
Cal-OSHA also said respirators should fail if they fail any portion of the test during maneuvers that simulate workplace movements and shouldn't be given three tries per person.
With or without new fit requirements, Berry Ann advises employers to fit-test some respirators brands or models to determine which would best fit their workers before they make a major purchase.
Getting better fitting respirators will be important to protect health care workers from the next possibly more serious pandemic, says Welsh.
"We were so lucky to get a dry run with H1N1. You couldn't have asked for a better situation to test our readiness for a more serious pandemic," he says, noting that H1N1 was not as deadly as many had feared. "We now know what we need to do to be much better prepared."
The 3M 8000 respirator recalled by the state of California as poorly fitting has passed muster in a review by the National Institute for Occupational Safety and Health (NIOSH). And Cal-OSHA, the state's occupational safety agency, is none too happy about it.You have reached your article limit for the month. Subscribe now to access this article plus other member-only content.
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