Fact or Myth: Sunscreen on Cloudy Days?

This is FACT.

Before we delve into why you should wear sunscreen on cloudy days, let’s first nip our fears of the sun in the bud. The best way to make sure you have enough vitamin D circulating through your body is to expose large surface areas of your skin to the sun. The trick is in the timing. For instance, if you are fair-skinned, you can produce the vitamin D you need by spending approximately 10 minutes SPF-free in the sun, preferably around noon when vitamin D from the sun is produced in the shortest amount of time. Any time past that initial 10 minutes, however, should be spent protected…even on cloudy days. Clouds filter sunlight, but not ultraviolet rays.

cloudy dayUV Rays on Cloudy Days

There are two types of UV rays: UVB rays, which inflict noticeable damage, like tan or burn, pretty immediately to your skin…and UVA rays, which damage skin under the surface, accelerating aging. UVA rays are the type to look out for on cloudy days. UV rays can seep through cloud cover, smog, and can even penetrate glass windows, putting you at risk for skin damage even if you are inside or driving. According to the American Academy of Dermatology, 80% of the sun’s UV rays pass through clouds.

There are, of course, certain factors, such as cloud thickness, type of cloud, and how much sky the cloud covers. But rest assured, if there are thin clouds in the sky, UV rays can definitely reach you at ground level. In fact, clouds can intensify UV rays, because these rays can bounce off the cloud’s edge.

Snow, ice, bodies of water, white sandy beaches, and concrete also intensify UV rays by reflecting the sun back to you, so you’re actually exposed to more sun rays. Snow reflects 80% of UV rays, while sand reflects 20%.

Your distance to the equator matters—the closer you are the more intense the UV rays, as does elevation—the higher you are, the closer you are to the sun and its rays.

What about shade? Shade isn’t the protector most people think it is. UV rays can actually bounce off air and reach you even when you are hidden in the shade.

By all means, go bask in the sun, even on cloudy days, for 10-30 minutes depending on skin tone and latitude, but protect your skin with SPF or sun-protective clothing the other 1440 minutes of the day.

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