By Alice || Edited by Go Ask Alice Editorial Team || Last edited Jun 23, 2023
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Alice! Health Promotion. "Shining light on sun protection products." Go Ask Alice!, Columbia University, 23 Jun. 2023, Accessed 15, Jul. 2024.

Alice! Health Promotion. (2023, June 23). Shining light on sun protection products. Go Ask Alice!,

Dear Alice,

I find choosing among all of the available sunscreens and sunblocks to be very confusing. Of the following three products I am currently using, which one is giving my skin the most protection: sunscreen SPF 30 with UVA, UVB, and IR sun protection; sunblock SPF 17 with UVA, UVB, and IR sun protection; or, sunblock SPF 50 with UVA and UVB sun protection? By the way, what is the difference between a sunSCREEN and a sunBLOCK?

Desperately Seeking Protection

Dear Desperately Seeking Protection, 

Walk into any pharmacy, and you’ll likely find a dizzying array of sun protection products and a sea of marketing claims. It can be difficult to know which products offer the best defense, so a bit of information on sun protection basics may help clear up some of the confusion: 

  • Ultraviolet (UV) rays: UV rays are invisible to your eyes and come in three types—A, B, and C. Only ultraviolet A (UVA) and ultraviolet B (UVB) rays reach your skin, and both pose some skin cancer risk. UVA impairs your skin’s ability to produce new skin cells, and lots of unprotected UVA exposure can lead to age spots, wrinkles, and cancer. UVB on the other hand is responsible for those harsh burns you can get after a day at the beach. UVB damages the outer layer of skin which inflames the blood vessels. Frequent UVB exposure can lead to skin cancer as well (but some UVB exposure—about 5 to 15 minutes a day—does a body good by producing vitamin D). 
  • Visible light: Visible light rays (the ones that help us see the world) are far less harmful than UV rays, but unprotected exposure can lead to the development of free radicals, or reactive molecules that damage cells and increase cancer risk. Visible light can also darken skin pigment or worsen melasma—dark brown or grey skin patches. 
  • Infrared radiation (IR): Just like UV rays, IR comes in three types—A, B, and C. Infrared-A (IRA) can penetrate the human skin. It has similar consequences as UV and visible light, including cell damage from free radicals and skin cancer, but there isn’t as much known about IR rays’ long-term effects as of now. What is known, however, is that presently, sun protection products don’t shield the skin from infrared rays. 

So, what do those mysterious SPF numbers mean? SPF stands for ‘sun protection factor’ and measures the proportion of UVB rays that the product filters out (there’s no system for measuring UVA protection quite yet). The Food and Drug Administration (FDA) recommend using at least SPF 15, which shields you from about 93 percent of UVB rays. The American Academy of Dermatology and the American Cancer Society on the other hand, recommend using SPF 30—especially for those with lighter skin—which filters out 97 percent of UVB rays. It’s been noted that SPF above 30 doesn’t provide much more protection.  A common misconception is that the higher the SPF, the longer you can stay in the sun. This simply isn’t true, and all sun protection products work best if reapplied every two hours. It’s also a misnomer that sunscreen is only for sunny days. Applying sun protection even when you’re outside on a cloudy day or in the wintertime is highly recommended. Last, but not least, make sure to check the expiration date to ensure that your product of choice is still at its original strength. 

Since sunscreen labels can be confusing, the FDA has established labeling requirements. The main restriction being the use of the term “sunblock” because no product can actually block the suns rays—they only filter or reflect some of the rays. The FDA has also banned use of the term, “waterproof” because sunscreens are only ever water resistant and must be reapplied after taking a dip or sweating excessively. A key phrase to look for when searching for a protective product is “broad spectrum,” which means that it protects against UVA and UVB (rather than just one). A sunscreen can only claim to reduce sunburn, skin cancer, and premature skin aging if it’s both broad spectrum and at least SPF 15. You might also see labels that say “physical” or “chemical” sunscreens, which just refer to the way the sunscreen protects your skin: 

  • Physical or “inorganic”: These products scatter both UVA and UVB rays away from the skin using zinc oxide or titanium dioxide. 
  • Chemical or “organic”: These products contain active ingredients or UV filters such as avobenzone or oxybenzone and absorb the UV rays before they can penetrate your skin. One thing to note is exposure to these sunscreen chemicals continues to raise concerns. Oxybenzone, for instance, has been linked to hormone abnormalities. 

All that said, choosing a sunscreen that protects against both UVA and UVB can be important when trying to avoid any long-term skin damage. In addition to using a broad-spectrum sunscreen that’s at least SPF 15, consider employing other protective measures to stay safe and protected from the sun's harsh rays such as: 

  • Avoiding or minimizing sun exposure from 10 a.m. to 2 p.m. 
  • Wearing clothing to cover exposed skin while in the sun 
  • Investing in a solid pair of sunglasses to protect your eyes 

As the science of sun protection advances, keep an eye out for information on new products, especially for those IR rays. If you’re looking for a fun way to remember some of this, check out the FDA’s ABCs of Sun Protection. Props to you for wanting to learn everything under the sun about sunscreens! 

Additional Relevant Topics:

General Health
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