You can find some useful information about ultraviolet radiation here: How Sunlight And Ultraviolet Radiation Affect Us The Angle Of The Sun And Vitamin D Production But UVA rays cannot stimulate Vitamin D production. Similarly, UVA rays penetrate glass and will still damage your skin while you are behind a window-such as during your daily commute or while you sit next to a window in your office. So even in the absence of UVB rays–like during the winter for much of North America, and when it is overcast–UVA rays are still present at high levels and still aging your skin. And UVA rays damage skin just like UVB rays. UVA Rays And Sun DamageĬonversely, UVA rays pass relatively unfiltered through the atmosphere, so regardless of the angle of the sun or cloud cover, a high percentage of UVA rays are still reaching the surface of the earth. Sunscreen lotion also blocks the production of Vitamin D. UVB rays have to strike your exposed skin to make Vitamin D creation possible.
If you are in your car or behind a glass window Vitamin D production isn’t possible. In some cities excessive pollution can be enough to severely limit the amount of UVB rays reaching the ground and, therefore, the potential to make Vitamin D.Īs a side note, UVB rays also don’t penetrate glass (or clothing). Similarly, UVB rays are also blocked by ozone and pollution. In addition to the atmosphere, clouds also block UVB rays, so if it is cloudy or overcast you probably aren’t going to produce any Vitamin D. If the sun is low enough, UVB rays are completely blocked by the atmosphere before they even reach you, and Vitamin D production is not possible. The more atmosphere UVB rays have to travel through, the more UVB rays are prevented from reaching the surface of the earth and the lower the sun is in the sky, the more atmosphere these UVB rays travel through. Yet UVB is reflected and blocked by the atmosphere. The reason is that UVB rays-and only UVB rays-catalyze the production of Vitamin D. But most significantly, the sun cannot stimulate your production of Vitamin D if the sun isn’t high enough in the sky.
There are many reasons why you won’t make Vitamin D in the sun-even during the middle of the day. People commonly think that if the sun is up and they are outside in the sun, they are going to produce Vitamin D.
There’s a lot of confusion surrounding sunlight and the production of Vitamin D.
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