What is SPF and how do I pick a sunscreen?
SPF means Sun Protection Factor. It is a measure of how long a sunscreen will protect you from ultraviolet (UV) B rays. The chief cause of reddening and sunburn, UVB rays damage the epidermis, skin’s outer layers, where the most common skin cancers occur.
How do I choose the sunscreen that is right for me?
- Choose a sunscreen with “broad spectrum” protection. Sunscreens with this label protect against both UVA and UVB rays. All sunscreen products protect against UVB rays, which are the main cause of sunburn and skin cancers. But UVA rays also contribute to skin cancer and premature aging. Only products that pass a certain test can be labeled “broad spectrum.” Products that aren’t broad spectrum must carry a warning that they only protect against sunburn, not skin cancer or skin aging.
- Make sure your sunscreen has a sun protection factor (SPF) 30 or higher. The SPF number is the level of protection the sunscreen provides against UVB rays. Higher SPF numbers do mean more protection, but the higher you go, the smaller the difference becomes. SPF 15 sunscreens filter out about 93% of UVB rays, while SPF 30 sunscreens filter out about 97%, SPF 50 sunscreens about 98%, and SPF 100 about 99%. No sunscreen protects you completely. The FDA requires any sunscreen with SPF below 15 to carry a warning that it only protects against sunburn, not skin cancer or skin aging.
- “Water resistant” does not mean “waterproof.” No sunscreens are waterproof or “sweatproof,” and manufacturers are not allowed to claim that they are. If a product’s front label makes claims of being water resistant, it must specify whether it lasts for 40 minutes or 80 minutes while swimming or sweating. For best results, reapply sunscreen at least every 2 hours and even more often if you are swimming or sweating. Sunscreen usually rubs off when you towel yourself dry, so you will need to put more on.