Sunscreen

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Exposure to ultraviolet light, UVA or UVB, from sunlight accounts for 90% of the symptoms of premature skin aging including wrinkles.[1] Sunscreens work by absorbing, reflecting, or scattering the sun's rays on the skin. They are available in many forms, including ointments, creams, gels, lotions, sprays, and wax sticks. All are labeled with SPF numbers. The higher the SPF, the greater the protection from sunburn caused mostly by UVB rays, but this does not increase the length of time for sun exposure. Broad-spectrum sunscreens protect against both UVA and UVB rays. They do a better job of protecting skin from other effects of the sun including photo damage, photodermatitis, and rashes from the sun.[2]

Contents

UVA, UVB, and UVC

The sun gives off ultraviolet (UV) radiation that we divide into categories based on the wavelength. UVC radiation is absorbed by the atmosphere and does not cause skin damage. UVB radiation affects the outer layer of skin, the epidermis, and is the primary agent responsible for sunburns. UVB does not penetrate glass, and the intensity of UVB radiation depends on the time of day and the season. UVA radiation penetrates deeper into the skin and works more efficiently. The intensity of UVA radiation is more constant than UVB without the variations during the day and throughout the year. UVA is also not filtered by glass. [1]

UVB rays cause sunburn and skin cancer; UVA rays cause aging and likely skin cancer.[3]

Stay out of the midday sun (from 10 in the morning to 4 in the afternoon), which is the strongest sunlight.[3]

Picking the Right Sunscreen

The SPF (sun protection factor) measures the amount of UVB absorption, but there is no method of reporting the UVA absorption. The only way to determine if a sunscreen protects against UVA and UVB radiation is to look at the ingredients. A good broad-spectrum sunscreen should have an SPF of at least 15 and contain avobenzone, titanium dioxide, or zinc oxide.[1]

Here are SPF ratings for some garments:

  • Nylon Stockings - SPF 2
  • Hats - SPF 3-6
  • Summer-weight clothing - SPF 6.5
  • Sun-protective clothing - up to SPF 30

[1]

  • Read product labels. Look for a waterproof brand if you will be sweating or swimming. Buy a nonstinging product or one specifically formulated for your face.
  • Buy a brand that does not contain para-aminobenzoic acid (PABA) if you are sensitive to that ingredient.
  • Try a sunscreen with different chemicals if your skin reacts badly to the one that you are using. Not all sunscreens have the same ingredients.
  • Use a water-based sunscreen if you have oily skin or are prone to acne.
  • Be aware that more expensive does not mean better. Although a costly brand might feel or smell better, it is not necessarily more effective than a cheaper product.
  • Be aware of the expiration date because some sunscreen ingredients might degrade over time.

[4]

Proper Application

  • Apply sunscreen approximately 30 minutes before being in the sun (for best results) so that it can be absorbed by the skin and less likely to wash off when you perspire.
  • Remember to reapply sunscreen after swimming or strenuous exercise. A common instruction is to reapply sunscreen after 2-4 hours in the sun.[1]
  • Apply sunscreen often throughout the day if you work outdoors, and wear hats and protective clothing.
  • Shake well before use to mix particles that might be clumped up in the container.
  • Sunscreen should be applied liberally enough to all sun-exposed areas that it forms a film when initially applied. It takes 20-30 minutes for sunscreen to be absorbed by the skin.[1] As a rule of thumb, use at least an ounce (a handful) to cover your entire body. Alternatively, fill a standard sized shot glass (ounce-and-a-half) with sunscreen to see exactly how much you should use on your body. Apply the sunscreen from the shot glass until it is empty.[5]
  • Use on all parts of your skin exposed to the sun, including the ears, back, shoulders, and the back of the knees and legs.
  • For the face, you should use about a teaspoon of sunscreen. Dot the sunscreen on your forehead, nose, cheeks, and chine. Blend the lotion out to your hairline, jaw, and ears and down your neck. Gently pat the sunscreen around your eyes.[5]
  • Regular sunscreen should be applied before eye cream; mineral sunscreen after it.[6]

All references in this section (except where noted):[4]

References

  1. ↑ 1.0 1.1 1.2 1.3 1.4 1.5 http://dermatology.about.com/cs/beauty/a/sunscreen_wrink.htm
  2. ↑ http://www.aad.org/public/publications/pamphlets/sun_sunscreens.html
  3. ↑ 3.0 3.1 http://www.webmd.com/skin-beauty/news/20080708/8-burning-questions-about-sunscreens
  4. ↑ 4.0 4.1 http://www.webmd.com/parenting/sunscreen-use-correctly
  5. ↑ 5.0 5.1 “Beauty 101: Sunscreen.” Allure. Pg 48. July 2009.
  6. ↑ "Younger Eyes." Allure. April 2010: Page76.
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