The Science of UV Rays
We’ve talked a lot about the importance of sunscreen to protect your skin from harmful UV rays, but how much do you know about UV rays? UV stands for ultraviolet, and ultraviolet light falls on the light spectrum between visible light and x-rays. You’ve likely heard about the damaging effects of UV rays such as sunburns and skin cancer, but did you know there are some benefits to UV light? For example, exposure to sunlight triggers the production of vitamin D in the human body, which helps “strengthen bones, muscles, and the body’s immune system.” UV rays can also be used to treat certain skin conditions such as psoriasis and to boost your mood. Additionally, “UV can effectively ‘kill’ (deactivate or destroy) microorganisms such as viruses and bacteria, for example, when hanging cloth nappies, underwear and tea-towels outside on the clothesline. To destroy the microorganisms, UV rays penetrate the cell's membrane, destroying the DNA, and so stops its ability to reproduce and multiply. This destructive effect explains why we can use UV antibacterial lamps for disinfection and sterilisation.”
However, this doesn’t mean you should completely forgo your sunscreen and stay outside until your skin turns into shoe leather. UV rays can cause sunburns and lead to skin cancer. In fact, “there is very strong evidence that each of the three main types of skin cancer (basal cell carcinoma, squamous cell carcinoma and melanoma) is caused by sun exposure. Research shows that as many as 90% of skin cancers are due to UV radiation.” Ultraviolet light can also damage the delicate tissue of the eyes and can cause a suppressing effect on the immune system. “Scientists believe that sunburn can change the distribution and function of disease-fighting white blood cells in humans for up to 24 hours after exposure to the sun. Repeated overexposure to UV radiation can cause even more damage to the body's immune system. The immune system defends the body against bacteria, microbes, viruses, toxins and parasites.” Overexposure to the sun can also prematurely age skin, making it harmful both inside and out.
All of this information might seem contradictory, but the true lesson is moderation. Basically, it’s important to leave your house once in a while because vitamin D is important, but make sure you limit your sun exposure and be sure to wear adequate sunscreen (and reapply often). You’re not a vampire, you need some sunlight, but you don’t want to go so far that you end up redder than a lobster. The American Academy of Dermatology recommends wearing broad-spectrum sunscreen that protects against UVA and UVB rays of at least SPF 30 and preferably waterproof. It’s okay to enjoy the sun,
 “Positive and Negative Effects of UV.” Science Learning Hub, www.sciencelearn.org.nz/resources/1304-positive-and-negative-effects-of-uv.
 "Sunscreen FAQs." American Academy of Dermatology. American Academy of Dermatologists, n.d. Web. <https://www.aad.org/media/stats/prevention-and-care/sunscreen-faqs>.