Study May Lead to Safer Clothes for Firefighters

Firefighters call it the “sting of the bees”--the moment an inferno begins to eat into human flesh.

If the protective thermal clothing worn by the firefighter isn’t up to the task, the heat can literally melt the flesh onto the inner layer of the clothing.

“You know whenever you feel the sting of the bees that you are getting burned,” said James Randall Lawson, a research scientist with the National Institute of Standards and Technology, but even the firefighter rarely knows the extent of the injuries he or she is experiencing.

“When you come out of the fire and take off the gear, that’s when you find out,” said Lawson, who is heading a new study of fire protective clothing. “You find that you’ve got a much larger area that’s been burned, or you’ve actually left flesh in your garment.”

Firefighting is a very dangerous occupation--a fact underscored this month by the tragic warehouse fire in Worchester, Mass., that claimed the lives of six firefighters. It is so stressful that, according to the International Assn. of Fire Chiefs, more than half the firefighter fatalities are from heart attacks.

In the last two decades, a lot of improvements have been made in the protective clothing that firefighters wear, and that should have taken some of the hazard out of the profession. But when Lawson and his colleagues at the National Fire Protection Assn. took a hard look at the statistics, they were in for a surprise.

“Even though there have been significant changes in the protective quality of the clothing and equipment that firefighters are wearing today, the rate of burn injury has remained basically constant over about a two-decade period,” Lawson said.

That finding intrigued Lawson and his colleagues at the National Institute of Standards and Technology, a non-regulatory arm of the Department of Commerce that works with industry to establish standards.

The result is a new approach to evaluating protective clothing, and it has already turned up some surprises. For example, research has shown that burn injuries require much less heat than had been thought, Lawson said.

Protective clothing consists of three layers--an outer shell, a moisture barrier and a thermal liner. Traditionally, the effectiveness of the material has been determined by measuring the amount of heat transmitted through all three layers.

Scientists at the institute decided to take a different approach and measure the effectiveness of each layer independent of the others. Tiny thermal couplers are placed throughout a 1-foot-square sample of the fabric.

“So we look at the components and basically instrument each level,” thus measuring the heat transfer as it moves through the garment, he said.

The research has shed more light on the role that water plays in producing injuries. Firefighters are frequently drenched by fire hoses, and they produce a lot of perspiration as they lug their equipment around and fight the blaze.

That moisture, trapped next to the firefighter’s body, can flash to steam, producing severe burns. So if the moisture barrier is not up to par, the garment will fail.

Previous systems measured only one level of heat--roughly equal to that produced by an average fire. But the new system can measure the effect of temperatures ranging from ordinary sunlight to intense heat produced by a blistering blast called a “post flashover fire environment.”

“One of the things we have learned is that the temperatures inside the clothing can produce burn injury even if they are much lower than had been thought,” Lawson said.

That, he said, is apparently due to more moisture getting through the protective clothing than had been anticipated.

It doesn’t feel as hot as it is inside the clothing, he said, “so you know you’ve been burned, but you don’t know how seriously.”

The institute hopes the research will lead to higher standards by the National Fire Protection Assn. and the U.S. Fire Administration. Representatives from the half-dozen or so companies that manufacture fire protective clothing are participating in the study, as are a number of firefighters.

At the very least, Lawson said, the research should lead to a better understanding of the limitations of the protective clothing. That, coupled with additional training, could bring down the number of burn injuries and possibly even lower the number of deaths among firefighters in this country every year. That number now stands at about 100.

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Lee Dye can be reached by e-mail at leedye@ptialaska.net.