The Sunscreen Breakdown: What's Really in the Bottle?
The sun protection factor (SPF) number on sunscreen bottles reflects the amount of protection from ultraviolet B (UVB) rays. The sunlight that reaches us is made up of two types of harmful rays: long wave UVA and short wave UVB. According to the US Food and Drug Administration (FDA), UVA rays penetrate deep into the skin’s thickest layer. Unprotected exposure can lead to premature skin aging and suppression of the immune system. And when your skin’s defenses are down, you’re at risk for skin cancer. On the other hand, UVB rays will usually penetrate the top layers of the skin, causing burning and skin cancer. UVA ray protection is not always configured into SPF ratings, but some broad-spectrum sunscreens may protect against them. According to the FDA, only sunscreens with an SPF of 15 or higher can claim protection against the skin cancer and premature aging risks that UVA rays increase. Products with less than an SPF 15 rating have only been shown to protect against sunburn (UVB rays).
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