Protective Vest for Reducing Occupational Exposure to Solar Heat Radiation

Vollständiger Abstract

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Occupational exposure to solar heat radiation is a major contributor to heat stress among outdoor workers, particularly in agriculture, where physically demanding tasks are performed under high ambient temperatures and direct sunlight. Infrared (IR) radiation represents a significant external heat load that can impair thermoregulation even when convective and evaporative cooling are present. A key research gap addressed in this paper is the limited understanding of how garment materials simultaneously influence both infrared (IR) transmission and IR absorption, and how these competing mechanisms affect net heat stress. This study evaluated garment materials and a prototype protective vest designed to reduce heat stress from solar IR exposure. Phase I measured IR penetration and IR absorption for cotton, polyester, paper, and Mylar using controlled radiant heat exposure and thermocouple measurements. Results showed that conventional fabrics reduced IR transmission but absorbed substantial radiant energy, leading to net heat gains of approximately 39–40%. In contrast, Mylar reduced IR penetration by 50% and offered a net heat loss of 15%. Phase II integrated the optimal material into a prototype vest incorporating the reflective Mylar foil and an 8.5 mm ventilation gap, which was evaluated using an inflatable thermal mannequin. Under IR exposure, the results showed that the prototype vest reduced the mannequin’s skin temperature by 26.4% and total body heat gain by 63.9% compared with a nude control and a standard polyester vest. These findings demonstrate that separating IR attenuation from absorption is critical in garment design. The results support the use of reflective, ventilated vest systems as a strategy for reducing occupational solar heat exposure.