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Layout of fire shelter field test. PHOTO CREDIT: John Williams, NCSU

As humans continue to encroach into wildlands, fire risks to property and health can result. This is especially true in the Western United States, where drought, high winds, and lightning strikes often lead to these disastrous fires. In 2022, .

Wildland firefighters serve on the front lines in a never-ending battle to preserve life and natural resources. This is an arduous job, with demanding physical and psychological fitness requirements. Long hours struggling through and over difficult terrain during fire season is a major challenge, making teamwork and good, rapid communications necessary. Add to these uncertainties due to weather changes, and firefighter safety can be threatened in a matter of minutes.

Layout of fire shelter field test. PHOTO CREDIT: John Williams, NCSU

Shelter from Danger

During a wildfire, firefighters identify locations that may offer some form of temporary safety, and directions leading to possible escape routes. But fast-changing conditions can sometimes close off these options. As a last resort, when cut off by the fire, these first responders must rely on their portable fire shelters for protection.Modern fire shelter development started in 1958. Each firefighter has a shelter, adding about five pounds to the weight they carry.

While the effectively reflects most of the radiative heat, other issues remain. After the disastrous , researchers studied ways to improve these shelters’ performance. Convective heat generated by direct flame contact leads to delamination of the adhesive (at 260 °C) used to bind the aluminum foil to woven silica fabric in the shelter’s inner and outer layers. The aluminized layer fails completely when the temperature exceeds 660 °C and the aluminum melts. In addition, additional convective heat-blocking layers and thermal insulation materials were lacking.

New Shelters

Layout of fire shelter field test. PHOTO CREDIT: John Williams, NCSU

In a recent article entitled (International Journal of Wildland Fire, 2022, 519—528. DOI: 10.1071/WF21102), researchers at North Carolina State University (NCSU) evaluated the performance of new fire shelter designs against the M2002 standard shelter, and compared results from the lab with those from field studies.

, professor in the College of Natural Resources at NCSU, and , professor and director of the Textile Protection and Comfort Center (TPACC) in the Wilson College of Textiles, NCSU, were the lead scientists involved in this work.

“[There are] a lot of differences [between structural and wildland firefighters’ gear]. Wildland firefighters are out for days and weeks performing very strenuous work. Gear must be lighter and more breathable,” says Barker. “TPACC’s broad research focus is on finding the balance between comfortable gear and protection from radiant heat in PPE worn by firefighters.”

Complicating matters are the growth of the so-called as human development into the wilderness blurs the distinction between structural and wildland firefighting.

PyroDome setup for laboratory fire shelter testing. PHOTO CREDIT: TPACC, NCSU

To study fire shelter performance, new fire shelter prototypes were developed at NCSU that featured new seam design, inclusion of new heat-blocking materials behind the outer layer, and use of compressible batting material as thermal insulation. They also developed new laboratory tests to evaluate their fire protection in controlled simulations of actual wildfire burn-over scenarios.

For full-scale lab testing, a test chamber called was used. To study how the lab tests translate to wildland fire exposures, field tests were conducted at different sites across North America. Several field test locations were selected based on the types of combustible plant materials present, the topography, and weather conditions. This proved to be somewhat of a challenge due to the many variables (e.g., heat and flame exposure, and unpredictability of winds) involved, but comparisons of relative performance among field tests were possible.

The PyroDome heat intensity used in the lab tests was similar to that measured in the field tests performed in a chaparral setting, although this intensity was on the low end compared to other field results. In general, the lab testing protocol for determining fire shelter performance provided the most reliable conditions for evaluation.

The Future of Wildland Fire Protection

Aftermath of fire shelter field test. PHOTO CREDIT: John Williams, NCSU

Work continues to improve fire shelter designs and advance the state-of-the-art in test methods for evaluating fire shelters used by wildland firefighters. Studies that help understand how the shelters perform in fire exposures are key to making progress in these technologies.

is a science editor, retired in 2021 from AATCC. He was primarily responsible for editing peer-reviewed articles for the ��ɫֱ��Journal of Research. His current interests are writing about industrial uses of new technologies, potential applications of emergent research, sustainability, and biomimicry.