Many firefighting uniforms contain an insulating material trade-named Nomex, a polymer made for decades by DuPont. The company has now developed a new version of Nomex that is thin and comfortable in everyday use, but grows three to four times thicker when temperatures rise above 121 °C, providing a 20 percent boost in thermal insulation. In March, DuPont began marketing the material in North America as a liner for firefighters' jackets; the company will market it globally by year's end.

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