Protection to thermal impact of solar radiation: evaluation of selected reflective fabrics

Prolonged exposure to solar radiation can cause considerable heat stress. The application of reflective materials in garments or sunscreens is generally considered as an appropriate protective strategy. In this study, we aimed to compare a range of reflective and control fabrics on their ability to reduce the thermal impact of solar radiation. We evaluated 16 reflective and 5 control fabrics, varying in applicability for garments and/or sunscreens. Transmission of ultraviolet, visible light and infrared radiation was studied using artificial solar light. Thermal impact reduction was first studied using artificial infrared light and secondly using natural sunlight, measuring temperature right at the back and 10 cm behind the fabric after a 10-minute exposure. Most samples showed comparably low radiation transmission (<10%). However, substantially higher transmission was observed in perforated and mesh-like reflective fabrics, as well as light-colored controls and coldblack® treated fabric. This resulted in larger temperature increases at 10 cm behind the fabric (+1-4°C in sunlight). Contact temperature at the back of the black fabrics ended up higher than at the back of the reflective and white control fabrics (T: 5-10°C in sunlight), the latter two showing minor mutual differences (T<3°C). In conclusion, the reflective fabrics (excluding perforated, mesh and coldblack®) showed minor mutual differences, lower heat absorption than the black control fabrics and lower heat transmission than the white ones. The results suggest that reflective or white fabrics are preferable for most garment applications, while reflective or possibly black fabrics are preferable for sunscreen applications.