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Understanding sunscreen: The As and Bs of UV skin damage

Everyone knows that daily sunscreen use is a great way to minimize skin-cancer risk and fight the signs of aging. But with so many choices out there, what is the “right” sunscreen? With some knowledge about how the sun can damage your skin and how sunscreen protects it, you’ll have an easier time finding the best products for you.

Two types of harmful rays reach your skin: ultraviolet A (UVA) and ultraviolet B (UVB).

UVA rays cause “age” spots and wrinkles, as well as skin-cancer risk. With a wavelength of 320-400 nanometers (nm), they are less intense than UVB rays but penetrate more deeply into the skin.

UVB rays cause that painful sunburn and, with repeated exposure, can lead to the development of skin cancer. They have a wavelength of 290-320 nm.

An easy way to remember the difference between UVA and UVB rays is that “A” is for “aging” and “B” is for “burning.” In order to protect your skin from both, it is important to use a sunscreen that is “broad spectrum,” coming as close as possible to covering the full UVA/UVB spectrum of 290-400 nm.

Get Physical with Your 

Sunscreens come in two types: chemical and physical.

Chemical sunscreens, such as oxybenzone (290-350 nm) and avobenzone (300-380 nm), absorb UV rays, then chemically break them down before they can cause damage.

Physical sunscreens last longer than chemical sunscreens. They are literally physical blocks, like a little wall on your skin, bouncing back the sun’s rays. Common physical sunblocks are titanium dioxide (290-370 nm) and zinc oxide (290-390 nm).

Not only does zinc oxide offer the broadest range of protection from UVA and UVB rays, but it is available in an improved, “micronized” form. Now products with zinc can be lightweight and invisible, unlike the thick, white, sticky ones of the past.

Aim High with Your SPF

Once you have found a sunscreen that offers the broadest spectrum of protection, you need to decide on level of sun protection factor (SPF). An SPF value compares the amount of time it would take to burn your skin without sunblock versus with sunblock.

An SPF 30 sunscreen blocks 97% of UVB rays, while — an SPF 50 blocks 98%! The American Academy of Dermatology recommends that everyone use a sunscreen with SPF 30 or higher daily.

What to do about that 2-5% of UVB light that gets through? Add an antioxidant to your skin, such as green tea polyphenols, resveratrol, or vitamin C. It’s your second line of defense to neutralize the harmful free radicals that are unleashed by sunlight.

Your Final Defense Strategy

Overall, your best bet against UV damage is to use a sunscreen with micronized zinc oxide and SPF of 30-50, combined with an antioxidant.

At California Skin Institute, we offer an outstanding line of sunscreens along with a comprehensive skin care program, including skin cancer screening, Mohs surgery for the advanced treatment of skin cancer and skin rejuvenation services.

Learn more about how we can help you protect your skin and keep Father Time at bay. Call us at (760) 633-1000 or visit our office at 700 Garden View Court, Suite 100, in Encinitas.

1 comment

Marc June 29, 2018 at 4:16 pm

The sun is not the enemy, but sunscreen may be; in fact, non-burning sun exposure is vital to human health. The research shows unequivocally that sun deprivation among children leads to myopia, rickets, and vitamin D deficiency. It is a mistake to advocate sun avoidance for our babies, children, or any other age group. Don’t take away sun exposure, just avoid sunburning. Much of the world is now vitamin D deficient, and for every death in the U.S. caused by diseases that are associated with sun exposure, there are about 328 deaths caused by diseases that are associated with sun deprivation. In the U.S, sun exposure has decreased by 90% since 1935. During that time the risk of melanoma has increased by 3,000%! Isn’t it interesting that each year the use of sunscreen increases, and each year the risk of contracting melanoma increases? It is not sun exposure that causes health problems; it is sun deprivation. And, it is leading to 336,000 deaths yearly in the U.S. There has also been an 8,300% increase in vitamin D deficiency in children since 2000, which is likely due to insufficient time playing outdoors and/or sunscreen use. So you see, all of this “protection” may be fatal. In addition, the Environmental Working Group (EWG) has released information that 73% of sunscreens don’t work and some may be counterproductive. A 20-year Swedish study demonstrated a 23% reduced risk of all-cause death among those women who used sunbeds (tanning beds).
•Seventy-five percent of melanoma occurs on areas of the body that are seldom or never exposed to sun
•Women who sunbathe regularly have half the risk of death during a 20-year period compared to those who stay indoors.
•A Spanish study shows that women who seek the sun have one-eleventh the hip-fracture risk as those who avoid sun.
•Men who work outdoors have half the risk of melanoma as those who work indoors.
•Women who avoid the sun have 10-times the risk of breast cancer as those who embrace the sun.
•Women who sunbathe regularly have half the risk of death during a 20-year period compared to those who avoid the sun.
•Sun exposure increases nitric oxide production, which leads to a decrease in heart disease risk.
•Sun exposure dramatically improves mood through the production of serotonin and endorphin.
•Sun exposure increases the production of BDNF, essential to a properly functioning nervous system.
More information: Or, read Dr. Marc Sorenson’s new book, Embrace the Sun, available at Amazon

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