Ultraviolet (UV) rays are a part of sunlight that is an invisible form of radiation. UV rays can penetrate and change the structure of skin cells. There are three types of UV rays: ultraviolet A (UVA), ultraviolet B (UVB) and ultraviolet C (UVC). Scientists believe UVA radiation can damage connective tissue and increase a person’s risk for developing skin cancer. UVB rays penetrate less deeply into skin, but can still cause some forms of skin cancer. Natural UVC rays are absorbed by the Earth’s atmosphere and do not pose a risk to workers.
Sunlight exposure is highest during the summer and between 10 a.m. and 4 p.m. Snow and light-colored sand reflect UV light and increase the risk of sunburn. At work sites with these conditions, UV rays may reach workers’ exposed skin from both above and below.