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What the AAD recommends about sunscreen, and why choosing the right sunscreen is important

Yasmin Aghajan MD

Why is sunscreen important?

Sunlight, while essential for synthesis of Vitamin D in the body, has ultraviolet (UV) radiation which causes both short- and long-term damage to skin. Skin damage ranges from sunburn and photoaging to the most feared, skin cancer. UVA rays (which are about 95% of the total UV radiation) are responsible for photoaging, skin pigment darkening, and may play a role in development of skin cancer. UVB rays, which are about 5% of the total UV radiation are responsible for sunburn, inflammation, and are known to cause skin cancer. Unlike many other types of cancer, skin cancer is preventable.

While there are some ways to avoid UV radiation exposure (such as avoiding sun at peak hours, wearing sun protective clothing), choosing and applying the right sunscreen is an essential step in protecting your skin from the sun’s damage.

What is SPF?

SPF stands for sun protection factor and it represents the sunscreen’s ability to protect against sunburn (caused by UVB rays). Technically, it is an experimental ratio obtained from applying the sunscreen to light-skinned volunteers and solar radiation (UVB) is applied while skin is monitored for a reaction. The higher the SPF of the sunscreen, a higher dose of radiation would be needed to cause a sunburn.

In simpler terms, the SPF is the strength of a particular sunscreen that protects the skin from UVB radiation. The amount of UVB radiation absorbed by SPF 15, 30, and 50 sunscreen is 93, 97, and 98 percent respectively. Products over SPF 50 do not provide much more added benefit.

What is a broad spectrum sunscreen?

Broad spectrum sunscreen must contain SPF of 15 or higher, and must pass the FDA test for protection against both UVA and UVB rays (as opposed to only UVB) rays. UVA rays which mostly cause skin aging, and UVB rays which cause sunburn are both blocked by broad spectrum sunscreen.

Official American Academy of Dermatology Recommendations

Dermatologists recommend choosing a sunscreen with SPF 30 or higher, broad-spectrum coverage, and water or sweat resistance. They recommend applying liberally and repeatedly to all sun-exposed parts of the skin. To achieve the full SPF of the sunscreen, the amount of sunscreen to cover an adult while on the beach is about 6 teaspoons, or about 1 ounce. Sunscreen should be applied 15-30 minutes before exposure to allow a protective film to form. Reapplication at least every two hours is recommended, even for products labeled as water resistant. The AAD recommends applying sunscreen even if outside on a cloudy day or in the winter, as the sun’s harmful UV rays are still present. In addition, people who got sunburned despite applying sunscreen usually didn’t use enough sunscreen and didn’t reapply it after being in the sun.

How to select a sunscreen

There are two types of sunscreens: organic (formerly called chemical) and inorganic (formerly called physical). There are pros and cons to different sunscreens. A sunscreen such as AstiVita zinc-based mineral broad spectrum sunscreen with SPF 50 and 40 minutes of water resistance meets all the criteria proposed by the AAD for sunscreen choice. Studies show that zinc based sunscreens do not significantly absorb into the bloodstream, in contrast to organic (chemical) sunscreens. In addition, choosing a sunscreen without fragrance or parabens that is also hypoallergenic without is suitable for sensitive skin, and reduces the amount of chemical exposure.


Sambandan DR, Ratner D. Sunscreens: an overview and update. J Am Acad Dermatol 2011; 64:748.



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