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Changing Faces: Respirator Testing Gets an Adjustment
Surely there is a message for education "standards" here. One size will never fit all.
Some Jobs Need a Mask,
But Diversity Is Challenge
For Keeping a Snug Fit
By Jane Zhang
PITTSBURGH -- The face of America is getting fatter and longer, and that's become a pain in the neck for Les Boord.
Mr. Boord is an engineer at the National Institute for Occupational Safety and Health, a federal agency dedicated to preventing workplace injuries. On the outskirts of this city long associated with steel making, he runs a 100-person lab that tests and certifies gas masks and other devices that protect workers from inhaling chemicals, dust, fumes and other harmful substances.
By law, all employer-supplied respirators, as these products are known, must be certified by NIOSH that they create an airtight fit on a broad range of faces. To ensure that they do, Mr. Boord, a 60-year-old with close-cropped gray hair and wire-rimmed glasses, each year puts hundreds of respirators through his lab's test chambers, using real people.
But finding people with facial features that match the average face in today's diverse workplace has become more difficult as the American mug has grown wider and more varied.
In the past few decades, as the beltlines of Americans have expanded, the faces of workers have gotten pudgier. The width, length and overall shape of workers' faces have changed, as more women, minorities and immigrants have moved into jobs previously dominated by white men of European descent.
This increasing diversity adds up to only small changes in the average size of American faces, but small changes can have big impact since respirators designed for the average have to accommodate so many different face shapes and sizes. These days, about 15% of the workers who use respirators on the job have trouble getting a proper fit from the respirators NIOSH certifies.
"Faces come in different sizes and shapes," says Mr. Boord. Americans, he adds, "are getting bigger." Even a small change "can have a big impact on the shape of a respirator."
For the record, Mr. Boord, thanks to Polish-Dutch heritage, has what for decades was a pretty standard American visage.
The changes in facial dimensions that NIOSH is tackling are tiny. Mr. Boord's lab has put together one statistical model of the average American man's face that is only 1.2 millimeters wider than an older, out-of-date version. That's about the width of a pencil point. The new model face is also 2.4 millimeters, or nearly a tenth of an inch, longer than the old one.
More than three million Americans, including miners, firemen, nurses and construction workers, use respirators on the job. The masks come in all shapes and sizes -- half masks, full-face, some with hoods. Some have their own air supplies, or use filters to neutralize toxic fumes.
Compounding the challenge of defining an average face for testing these devices is a difference of opinion over which characteristics are most important in ensuring a representative sample. One study of facial characteristics that NIOSH conducted emphasized nose protrusion, while a different study pointed out the importance of nasal root breadth -- the width on the nose near the area where it meets a person's eyes.
For years, Mr. Boord's lab has recruited people from the Pittsburgh area to test respirators. The testers qualify to participate if their faces match a set of dimensions developed in 1972 by Los Alamos National Laboratories using facial dimensions taken from 4,000 Air Force servicemen.
Last summer, Tom Vogt, a 40-year-old paramedic and volunteer firefighter, who fits the Air Force facial criteria, pulled on a full-face respirator with a green air tank and stepped into a 12-foot-by-12-foot chamber chilled to 16 to 32 degrees below zero. Mr. Vogt, who is of German heritage and has tried some 150 respirators for NIOSH since moving to Pittsburgh two years ago, spent 30 minutes in the chamber, alternately sitting and walking up and down a step-box to simulate work.
He and other testers are paid $25 to $75 per test session. Mr. Vogt says it is satisfying to "leave my mark" helping NIOSH.
But Mr. Boord now needs testers with faces different from Mr. Vogt's. The Air Force criteria were based on mostly white, young and physically fit men -- a group unlike today's typical fireman or hard hat. Fully 87% of all firefighters, 73% of American health-care workers and 91% of those in law enforcement are overweight or obese, according to NIOSH.
In 2001, Mr. Boord's lab paid a company called Anthrotech Inc. $400,000 to create a database of facial characteristics, in hopes of coming up with better guidelines for selecting respirator testers. The company measured the foreheads, chins, eyes and other features of 4,000 people from eight states.
The effort was judged inconclusive for Mr. Boord's purposes by experts from the National Academy of Sciences who reviewed Anthrotech's work for NIOSH. They found the results didn't fully capture the diversity of the U.S. population. Among other things, it said the company relied too much on states with large populations of white Americans of Europeans lineage, and didn't give enough weight to states like California that have large Asian and Hispanic populations.
Bruce Bradtmiller, president of Anthrotech, Yellow Springs, Ohio, says "it's almost impossible" to find a sample that precisely matches the racial reality of America. But he adds that Anthrotech used statistical weighting to correct any shortcomings in its data and believes the results were accurate.
Manufacturers of gas masks and other respirators are testing new materials and designs to make their products fit a broader range of faces. Some are working with soft silicone rubber that squishes into different shapes to fill in any gaps. Others are looking at inflatable fittings to do the same thing.
In the meantime, Mr. Boord is turning his efforts to new statistical models for choosing real-life testers. One uses the Air Force data as a starting point but makes the average face size slightly longer and wider. That's where the increases of 1.2 and 2.4 millimeters come from. The other uses complex, 10-dimensional data that look at nose protrusion, jaw width and other dimensions.
A paper on these methods authored by scientists in Mr. Boord's lab will soon be published in a peer-reviewed journal. If the paper receives positive feedback, NIOSH may start using the new methods to identify respirator testers in a few years.
Wall Street Journal
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