Liberally-applied sunscreen is the prescription for protection against the sun’s UV rays. Medical experts caution that exposure to UVA and UVB radiation may cause skin cancer. Some medical experts are adamant that sunscreen and adequate clothing coverage are paramount for protecting skin, but other healthcare professionals teach the importance of getting just enough sun.

Ultraviolet radiation travels in waves, like those of a lake or an ocean. Some waves are long and can penetrate deeply, while others are short and less likely to travel as far. In “Understanding UVA and UVB,” the Skin Cancer Foundation explains that, while UVB radiation is more intense, up to 95 percent of the radiation reaching the Earth’s surface is UVA.


UVA Radiation

The skin usually reacts in two different ways to the sun: tanning and burning. UVA rays penetrate the skin more deeply causing the skin cells to react by producing more melanin, a pigment that causes the brown coloration. This produces a tan. Repeated tanning can stress the skin and promote wrinkling and aging.

Melanin production is a defense mechanism against the sun’s raise. Cells in black skin produce more melanin on a regular basis, which is why the skin is dark. It also protects against UV radiation more effectively than white skin. This is why it is less susceptible to developing skin cancer that is caused by sun exposure (there are other causes of skin cancer).

UVB Radiation

UVB radiation’s intensity causes the skin to sunburn. The Skin Cancer Foundation warns, “Its intensity varies by season, location, and time of day. The most significant amount of UVB hits the U.S. between 10 a.m. and 4 p.m. from April to October.”

UVB radiation is not without its benefits, however! According to the study, “Sunlight, UV-radiation, vitamin D and skin cancer: how much sunlight do we need?” by M.F. Holick, UVB radiation breaks down provitamin D₃ so that the body can further convert it to vitamin D₃, also known as cholecalciferol. Vitamin D deficiency has been linked with the development of many diseases such as multiple sclerosis.

UVC radiation never reaches the Earth’s surface because it is completely absorbed by the Earth’s atmosphere.

Sunlight Exposure for Vitamin D₃ Production

In spite of health alerts that sunlight can damage skin and cause cancer, many people prefer to get some sun exposure for vitamin D₃ production. Many physicians and health advocates recognize the benefit of the sun, and believe that appropriate sun exposure is best for one’s health, usually less than 20 minutes at a time. To stimulate vitamin D₃ production, you must spend time in the sun without wearing sunscreen.

“You can tell you’ve reached your optimal exposure for the day when your skin turns a very light shade of pink,” Dr. Mercola said in his article, “How Much Sunshine Does it Take to Make Enough Vitamin D? Perhaps More Than You Think!” “After that you’re only increasing your chances of getting burned, which is something you definitely want to avoid. There is NO additional benefit to staying in the sun any longer.”

Ola Engelsen of the Norwegian Institute for Air Research published an online calculator, “Calculated Ultraviolet Exposure Levels for a Healthy Vitamin D Status,” which determines how much sunlight you need to maintain healthy vitamin D₃ levels. The calculator asks for information that affects the intensity of the sunlight, such as location, elevation, skin color, etc. You may find elevation by searching for your zip code at the National Weather Service website. The NWS also gives the elevation in feet. This must be converted to kilometers. This can be easily done by going to Google and typing in the search box: “convert [your elevation goes here] feet to kilometers. Press enter and Google will return the answer above the search results.

Some might say that sun exposure is a necessary evil. Some diseases are more prevalent in areas of less sun exposure, further from the equator, supporting the idea that some sun exposure is good sun exposure.

Tweet