All About Sunscreen
Written By: Natalia Loomis
Contrary to popular belief, sunscreen for your face should be incorporated into your skin regimen every day, not just in the summer but also when you are going to the beach and pool. The sun gives off radiation which can be harmful to the skin and lead to sunburn and eventually skin cancer (melanoma and squamous cell carcinoma just to name a few). The sun gives off both UVA and UVB rays; proper sun protectant should block both. UVA consist of 95% of solar radiation and suppresses the immune system by affecting primary and memory t cell function. UVB is only 5 % of solar radiation, however it is responsible for most skin damage and is more intense during the summer and mid-day. Another misconception is that sunscreen and sunblock are the same products, and the word is often used interchangeably. However, sunscreen and sunblock are two different things. Sunscreen is a chemical defense which forms a film or coating on the surface of the stratum corneum which absorbs the UV rays before they reach and damage the dermal layers. Some sunscreens include avobenzone, oxybenzone, and Para-aminobenzoic acid (PABA). Sunblocks are agents which scatter radiation, these are opaque particles of inorganic materials. Typically, sunblock includes zinc oxide or titanium oxide. Sunblocks are often opaque and noticeable when applied to the skin.
According to the Skin Cancer Foundation, for those with sensitive skin, sunblocks are better tolerated and provide less irritants than sunscreen. Those who might have certain skin conditions such as rosacea or psoriasis should avoid sunscreen as the active ingredients, oxybenzone, and PABA, could cause a reaction. Also, these patients should only purchase fragrance free, and if possible preservative free sun protectants. Additionally, for infants (6 months and older) and small children sunblock is preferred over sunscreen. When searching for a sun protectant it should be at least an SPF of 30, but an SPF of more than 70 will not really provide additional benefit. Furthermore, it should be broad spectrum protection (protection against both UVA and UVB rays) and water resistant. SPF stands for Sun protection factor, which indicates how well a product will protect you from the suns UV rays. The SPF number tells you the amount of time it takes for the skin to burn upon exposure to the sun with protection as opposed to non-protection. For example, if a person normally burns in 10 minutes and applies SPF 30, now they can stay in the sun for 10 x 30 = 300minutes before burning. If used exactly as directed, a product with SPF 30 will take the sun 30 times longer to burn the skin than skin directly exposed without protection. A product with SPF 50 will take 50 times longer.
Finally, when using and applying sunscreen, proper application is more important than SPF number. Apply the product 15- 30 minutes prior to sun exposure to allow absorption through the skin. Reapply every 2 hours if tanning/ sunbathing, and every 40-80 minutes if swimming. Additionally, avoid the direct sun from 10:00 A.M. – 3:00 P.M; when the sun is the strongest, wear sunglasses that filter UV light, and wear protective clothing such as opaque long sleeve shirts, pants, and a hat.
(1) Elchaar, Gladys. Sunprotection: Clinical application. Lecture presented at St. John's University. September 2019. Queens, NY
(2) Tamminga MA, Lipoff JB. Understanding sunscreen and photoprotection misinformation on parenting blogs: A mixed-method study. Pediatr Dermatol. 2021;38(1):88-91.