Shedding some light on Sunscreens: FAQs about UV Protection

The topic of sunscreens and ultraviolet (UV) radiation protection can be very confusing.

The bottom line is we should all be using some sort of topical protection from UV radiation exposure.

  • Skin cancer accounts for over 50 % of cancers annually in the US, and there has been startling increases in skin cancers such as melanoma.
  • UV radiation plays a role in skin cancer and is considered a carcinogen.
  • UV radiation can lead to premature skin aging, wrinkles and skin pigment changes.

Sunscreens and sunblocks do help to protect against the harmful effects of UV radiation, but there are so many products and terms out there, choosing UV protection can be confusing and difficult. Here are some frequently asked questions (FAQs):

What is UV radiation? Ultraviolet radiation is harmful light energy dispersed by the sun. It has two forms UVB and UVA.

  • UVB has a wavelengths of 290 to 320 nm and are the causative energy that cause sunburns. These have been linked to skin cancer formation
  • UVA has a wavelength of 340 to 400 nm are longer wavelengths which can penetrate glass and can lead to deeper skin damage without a superficial burn. UVA has been linked to malignant melanoma.

These two types of UV radiation are important when considering sunscreens which protect only variable wavelengths.

  • Sun blocks do a great job of blocking both.

What is SPF? SPF or the Sun Protection Factor, is calculated by the minimum erythema dose (or the amount of energy exposure to cause redness) in sunscreen protected skin to that of unprotected skin.

Sun Protection Factor (SPF) =  Minimum erythema dose for sunscreen protected skin / Minimum erythema dose for sunscreen unprotected skin

  • This could be translated into sunscreens ability to increase the time that can be safely spent in the sun before redness.

What is the difference between sunscreen and sunblock?

  • Sunscreens contain active agents which absorb, reflect or scatter UV radiation and convert it to heat.
  • Sunblocks provide a physical barrier to the radiation, but also can convert it to heat.

Does a sunblock have to be white? Sunblocks provide a physical barrier to UV radiation and classically were opaque and hard to use. Sun blocks have been micronized and the Zinc Oxide or Titanium Dioxide particles are now very small. When applied onto the skin they appear clear, but still provide the same protection.

How do I apply sun protection? Sunscreens should be applied in a proper amount on dry skin. About one half to a full teaspoon on each body part. It should be reapplied every one to two hours depending on activity, moisture and sweat. The calculation for SPF was very standardized, and this is hard to replicate at the pool or before a sporting event.

  • Proper amount and re-application are the best ways to maintain the protection of the products listed SPF.

What do I do if I my sunscreen causes me to break out? Active chemicals and inactive emollients can cause irritation, break-outs, and sensitivities. This can happen after the sunscreen is exposed to light on the skin. If irritation does occur, you may consider to change products.

  • Sunblocks typically have a low potential for irritation

Can I use my sun protection with other products? Sun protection can be combined with moisturizers for daily use, or with antioxidants to help increase protection against the harmful damage caused by the sun.

Dr. Andrew P. Trussler at his plastic surgery office in Austin Texas can help to determine what sunscreen product is right for you and your skin. The plastic surgery office in Austin has a full line of EltaMD sun care products for all skin types, including face and body protection.


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