NIOSH: N95s must fit most faces

Proposed rule would ease fit-tests

Finally, there's some relief in sight from the frustrations of fit-testing N95 respirators. Manufacturers will be required to make respirators that fit most people well under a rule proposed by the National Institute for Occupational Safety and Health.

No, this doesn't mean freedom from fit-testing. But it does put more of the burden for fit on the producers of respirators and it should mean fewer failures in fit-testing from the brands you select, explains Roland Berry Ann, deputy director of the NIOSH National Personal Protective Technology Laboratory in Pittsburgh.

"When the respirator goes into the workplace, it'll have a greater chance of fitting a larger portion of the work force," he says. "[N95 respirators] are still going to require fit-testing to make sure they fit you as an individual. It's more likely that respirator [certified under the proposed rule] will fit you than one that hasn't demonstrated the high percentage of passes across a range of facial sizes."

With the proposed "Total Inward Leakage" rule, NIOSH would create a significant new requirement for respirators certified by the agency. Only NIOSH-certified respirators can be used in workplace respiratory protection programs. NIOSH was accepting comments through Dec. 29. Respirator manufacturers will have three years after the rule goes into effect to comply with the new requirements.

To pass a fit-test, respirators must have only 1% of leakage through the face seal and filter — or a "fit factor" of 100. "The assigned protection factor, or the level of protection you'd expect to receive in a work site, is 10," which means the actual leakage during use could be as high as 10%, Berry Ann says.

How many respirators currently on the market would flunk the new requirements? NIOSH tested 101 models and 30 failed.

That does not mean that respirator supply will drop by 30%, says Berry Ann. While they represent almost a third of the available brands, few of them may be produced and sold. "We don't know how many of those there are in the marketplace," he says.

The proposed rule also may influence changes in the respirator market. "Some manufacturers may see the potential of [their] products not being able to be certified and may come up with new products to fill the void," he says.

Rule may not hurt supply

Respirators that pass the proposed Total Inward Leakage test will fit a wide variety of faces. To create the new certification criteria, NIOSH first conducted "anthropometric" research — a search for a panel of 35 people who represented the diversity of the United States.

To receive certification, a respirator model (available in several sizes) must be capable of fitting at least 26 of the panel of 35 using a quantitative test with a TSI Portacount. That level creates the greatest fit-test reliability, says Berry Ann. "It maximizes good fits not failing erroneously and bad fits not being accepted erroneously," he says.

Manufacturers also may demonstrate that a model fits at least 12 of 15 people in a defined subgroup. For example, most health care workers are women, and respirators might be designed that fits the facial structure of women better than that of men.

Meanwhile, the demand for well-fitting respirators in health care has inspired new products. For example, Safe Life Corp. of San Diego has introduced an N95 respirator that resembles a surgical mask. The company touts it as being more comfortable than traditional cone shape or duck bill.

The FaceSeal respirator, which attaches with adhesive rather than straps, represents a breakthrough in design as it relates to fit, Berry Ann says. The FaceSeal passed the Total Inward Leakage test. The user must make sure that the adhesive is properly attached around the facepiece, he says.

"Whether or not it will catch on or whether people will find it more comfortable or less comfortable, we'll find out from user demand," he says.

[Editor's note: The proposed rule was published in the Federal Register on Oct. 30, 2009, and can be found at Until Dec. 30, 2009, comments can be submitted to for RIN 0920:AA33 or to (include RIN number and 42 CFR part 84 in the subject line.)]