Why is sunscreen important?

Fri, 06/10/2022 - 2:30pm
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As the summer returns and we start spending more time outdoors, this is your annual reminder to wear sunscreen! Using sunscreen to protect your skin is necessary year-round, but with more hours of sunlight and warmer weather, using appropriate sunscreen and skin protection becomes extra important in the summer. While we imagine this is not your first time hearing about sunscreen, we’ll be going through some of the basics of how sunscreen works and why it’s so essential in staying healthy long term.
Sunscreen’s job is simple, to protect the skin from ultraviolet light generated by the sun from penetrating our skin. UV radiation makes up approximately 10 percent of the light produced by the sun and can be further broken down into the three subbands of UV-A, UV-B, and UV-C light.
Now, some things can be good in moderation. The human body needs UV-B light to reach the skin to produce Vitamin D. Ten to 15 minutes of sun exposure, two to three times a week is enough to meet your bodily needs of Vitamin D. Luckily, sunscreen does not interfere with this process.
On the other hand, too much UV-B causes an inflammatory response resulting in what we know as “sunburn” and death of skin cells. By protecting skin from UV light, sunscreen helps prevent sunburn. More importantly, sunscreen also helps prevent skin cancer, which is a result of accumulated damage to the DNA caused by too much UV-B penetration. Through a similar process, UV-A reaches a deeper skin layer, called the dermis. Changes to the cells in this skin layer lead to visible skin changes such as irritation, changes in color, fine lines, wrinkles, sagging through loss of skin elasticity, and eventually the development of skin cancer.
These various changes in your skin can appear immediately after too much sun exposure in the form of sunburns or blisters, or they can appear years later as signs of early aging or skin cancer. Many other factors such as family history and exposure to additional toxins play a role in the development of skin cancer but protecting yourself from UV light is a highly effective way to take skin cancer prevention into your own hands.

Did you know…?

• UV radiation increases by six to eight percent per every 1000-meter increase in altitude.
• Fresh snow reflects up to 80 percent of UV rays. You can get sunburnt in the snow.
• Sand reflects up to 25 percent of UV radiation, increasing one’s UV exposure at the beach.
• 95 percent of UV radiation penetrates water with up to 50 percent traveling three meters below the surface. UV rays also reflect off of water. Wear water resistant sunscreen.
• UV rays shine through light clouds and glass. Wear sunscreen even on cloudy days and when indoors.

Selecting your sunscreen

The two primary types of sunscreen are mineral and chemical sunscreens with the most effective forms of sunscreen using active ingredients from one or both of these categories.
Mineral sunscreen works as a protection barrier. Mineral sunscreen contains titanium dioxide and/or zinc oxide that sit on top of your skin and block UV radiation from entering the epidermis. Because these sunscreens work as a barrier, they are effective immediately but may leave more of a white cast than chemical sunscreen.
Chemical sunscreens absorb UV light, then transform and release the absorbed UV light as non-damaging heat. Active ingredients in this category of sunscreen include oxybenzone, avobenzone, octisalate, octocrylene, homosalate, and octinoxate. Chemical sunscreens are absorbed by skin so they leave less of a white cast; however, they become effective 15 to 20 minutes after application because of the time needed for skin to absorb it.
SPF is a measurement that reflects the percentage of UV light that a given sunscreen protects against. A SPF 15 sunscreen blocks 93 percent of UV-B light and SPF 30 blocks 97 percent. After that, the difference in protection is small. SPF 50 blocks 98 percent, and SPF 100 blocks 99 percent of UV-B light. Any sunscreen SPF 30 or above is a great option. What is more important than the highest SPF available is consistently using and reapplying sunscreen every two hours while in the sun.
“Broad Spectrum” sunscreen refers to a sunscreen’s ability to protect against both UV-A and UV-B light. When selecting your chemical or mineral sunscreens, be sure to select broad spectrum options.

Our recommendations:

• Choose a physical and/or chemical sunscreen that is broad-spectrum and SPF 30 or above.
• Reapply sunscreen every two to three hours and remember to apply on highly- exposed areas (ears, hands, tops of feet, back of the neck, exposed scalp, and lips).
• Be sure to reapply after contact with water, for example, swimming or excessive sweating.
• Using sun-protective clothing and hats can provide additional sun protection.

Juli Brown and Idara Ndon are medical students from Brown University working at the Block Island Medical Center.