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Encore: A new hard hat could help protect workers from on-the-job brain injuries

RACHEL MARTIN, HOST:

More than 30 million workers in the U.S. wear safety helmets to prevent head injuries. Yet most of these hard hats offer little protection against serious impacts. Here’s NPR’s Jon Hamilton.

JON HAMILTON, BYLINE: Concussions, or mild traumatic brain injuries, get a lot of attention when they happen on a football field. But these injuries are far more numerous in another setting. Michael Bottlang directs the Legacy Biomechanics Lab in Portland, Ore.

MICHAEL BOTTLANG: Where do the most brain injuries happen that should be prevented? It's really among workers, construction workers, anybody wearing hard hats.

HAMILTON: About a quarter of all concussions in adults occur on the job. And Bottlang says one reason is that hard hats, unlike football helmets, haven't changed much.

BOTTLANG: Unfortunately, today's most frequently used hard hats look identical to the ones from the '60s.

HAMILTON: There's a plastic outer shell with an inner suspension system made from webbing. Some models also include foam padding on the sides and a chinstrap. This design does a fine job protecting the brain from a direct hit. But hard hats aren't so good when the impact comes at an angle. Bottlang says that's because the helmet, and the head inside it, turns violently.

BOTTLANG: Think of a boxer, get knocked in the chin, makes the head spin, and you drop like a fly. The human brain is readily injured by a rotational force.

HAMILTON: The brain is a bit like an egg yolk, a soft capsule surrounded by liquid inside a hard shell. You can shake an egg forcefully without disrupting the contents. But if you spin one hard enough, the yolk inside will rupture. Dr. Steve Madey, an orthopedic surgeon in Portland, says most hard hats and helmets act like an eggshell.

STEVE MADEY: They do a job at reducing force, so they serve a purpose. But if they're not optimized to decrease the spin, they're not optimized to prevent injury.

HAMILTON: So Madey and Bottlang founded a company called WaveCel to make better helmets. Their inspiration came from observing what happens to a ball when it strikes the ground at an angle. Madey says ordinarily, the ball does more than just bounce.

MADEY: It'll hit the ground, it'll have friction, and it'll create spin.

HAMILTON: Unless the ground is made of something special.

MADEY: If you throw a ball into a sandpit, the sand gives underneath, right? It doesn't impart spin to the ball.

HAMILTON: So the company developed a helmet liner made from a special plastic honeycomb designed to act like sand.

MADEY: The honeycomb structure is a very light, breathable material that is not only good at absorbing that linear force but also breaks that spin the way sand would.

HAMILTON: The liner can be found in several big-brand sports helmets. And now WaveCel is offering its own line of hard hats. In both sports helmets and hard hats, the company faces competition from the Swedish firm MIPS. Studies show MIPS technology also reduces spin but not as well. A WaveCel hard hat costs $189, several times the price of a standard helmet. And it's not clear whether any sort of anti-spin technology will become standard on job sites. Dr. Brandon Lucke-Wold, a neurosurgeon at the University of Florida, says he has yet to see much change.

BRANDON LUCKE-WOLD: Even the construction workers I saw biking home today were wearing hard hats that are very similar to what I saw 10, 15 years ago.

HAMILTON: Lucke-Wold says that's one reason he's still treating patients who get a concussion despite wearing a hard hat. So he'd like to see more workers in helmets that help reduce the speed at which the head spins in an impact.

LUCKE-WOLD: By having this slowing process from these helmets, it's keeping the brain more stationary. And so that has a lot of potential benefit.

HAMILTON: Including keeping workers out of the hospital and on the job.

Jon Hamilton, NPR News.

(SOUNDBITE OF SIGNAL HILL'S "A SECRET SOCIETY") Transcript provided by NPR, Copyright NPR.

Jon Hamilton is a correspondent for NPR's Science Desk. Currently he focuses on neuroscience and health risks.