Infrared rays in sunlight have a different effect on the skin than ultraviolet rays. Ultraviolet light causes photochemical and photoimmune reactions, while infrared radiation produces reactions due to molecular vibration and temperature increase. The thermal radiation caused by infrared rays penetrates the skin more than UV rays. 25% to 65% of its radiation reaches the epidermis and dermis, and 8% to 17% reaches the subcutaneous tissue. Infrared radiation through its thermal radiation effect makes the skin temperature rise, capillary dilation, congestion, increased epidermal water evaporation and other direct adverse effects on the skin. The main manifestations are red pimples, premature aging of the skin and pigmentation disorders. Elevated skin temperature, capillary expansion, congestion, increased epidermal water evaporation and other direct adverse effects on the skin.
Infrared rays also enhance the damaging effects of ultraviolet rays on the skin, accelerating the skin's aging process. Using the same sunscreen products and the same energy intensity of ultraviolet rays, outdoor natural sunlight measured SPF value (sun protection factor) is significantly lower than that measured in the laboratory under the artificial light source of sunscreen effectiveness, which is due to the natural sunlight, the skin by ultraviolet and infrared rays caused by the dual role of the cause. Infrared and UV light play the same role in accelerating tissue degeneration. Infrared also promotes the development of UV-induced skin cancer. I hope this helps you!