Sunscreen is one of the most effective ways to protect yourself from the sun. Applying sunscreen is important due to the risk of sun damage and skin cancer. Exposure to the sun causes most of the blemishes we seek to avoid, and can lead to much more serious consequences, including skin cancer.
Skin cancer is the most common form of cancer in the US primarily caused by the ultraviolet (UV) radiation from the sun. There are three main types of skin cancer: basal cell carcinoma, squamous cell carcinoma and melanoma. Basal cell and squamous cell cancers are less serious types and make up 95% of all skin cancers. Melanoma is the most serious form of skin cancer and causes 75% of all skin cancer deaths.
A broad-spectrum sunscreen protects against ultraviolet A (UVA) and ultraviolet B (UVB). UVA where A stands for aging causes damage below the skin surface and UVB where B stands for burning protection. UVA rays can prematurely age your skin, causing wrinkling and age spots. UVB rays can burn your skin. Too much exposure to UVA or UVB rays can cause skin cancer.
SPF is a measure of how well sunscreen protects against the UVB rays. SPF is calculated based on how long it takes to sunburn skin treated with the sunscreen compared to skin with no sunscreen. For example, if someone would normally burn in 5 minutes, an SPF of 10 would extend the time they would burn to 50 minutes. However, since the intensity of sun varies during the day, the sunscreen will not last for more than a couple of hours. The American Academy of Dermatology (AAD) recommends a minimum SPF of 30.