Fabric Performance during (IR) Heat Radiation Exposure

Workers exposed to outdoor solar heat radiation in hot and dry climates are often at increased risk of heat related disorders. Exposure to heat radiation from the sun is a major contributor to heat stress. Protective clothing can be used to reduce such exposures. However, the attenuation of infrared heat by a garment can be offset by an increase in garment temperature build-up due to the retention of metabolic heat. This can "counteract" the IR attenuation benefits offered by the clothing. An accurate understanding of this "trade-off" relationship is needed to optimize the selection of fabrics in managing heat stress resulting from exposure to solar IR heat radiation. Laboratory experiments were performed on multiple layers of Cotton, Nylon, Wool and Polyester fabric samples to evaluate their heat insulation characteristics and IR heat attenuation properties. The relationship between fabric layers and IR attenuation properties was examined under controlled laboratory temperature conditions. The results of this study showed that fabric insulation heat gain and corresponding IR radiation attenuation was proportional to the number of fabric layers used. However, the IR heat radiation attenuation was significantly greater with each additional fabric layer than the heat gain "penalty" associated with fabric insulation. This suggests that multiple fabric layers can significantly reduce the risk of IR heat radiation overexposure while limiting the metabolic heat build-up inside protective clothing. The study confirms that by selecting the appropriate number of fabric layers, it is possible to optimize the IR heat radiation protection while limiting metabolic heat build-up inside the clothing.