Sun Safety

The following information and resources can help you and your family learn how to enjoy the outdoors while practicing sun safe habits.



About Sun Safety

The amount of exposure you get from ultraviolet (UV) radiation depends on several factors:

  • Time of Day: Maximum exposure to UV radiation occurs between 10 am and 4 pm.
  • Season: Intensity of UV radiation is much greater during the summer months.
  • Altitude: UV radiation increases by 4% per 1000 feet elevation. For example, there is 20% more UV radiation at 5000 feet (most ski resorts) than at sea level.
  • Cloud Cover: A thin cloud cover reduces UV radiation by only 20-40%.
  • Reflection: Reflected UV radiation is just as damaging as direct UV radiation.
    • Sand/concrete reflects 25% of UV radiation.
    • Water reflects up to 100% of UV radiation.
    • Snow reflects 85% of UV radiation.
  • Protection: It is the best way to reduce your risk of skin cancer and photoaging.
    • Sunscreen
      • At least 15 SPF
      • Applied 20 minutes before sun exposure
      • Reapplied as needed, especially while swimming or sweating
    • Hat
      • A 4-inch brimmed hat reduces sun exposure by 70% to your head, neck, and face
    • Sunglasses
      • Select sunglasses and eyewear that block 99% to 100% of UVA and UVB radiation
      • Children need smaller versions of real, protective adult sunglasses - not toy sunglasses
    • Clothing
      • A white, dry cotton shirt provides an SPF of about 8
      • The SPF increases if the fabric is dyed or is thicker
      • Wet clothing allows about 50% transmission of UV radiation
    • Sun Exposure
      • Limit your time in the sun between 10 am and 4 pm when the UV rays are strongest
  • UVA vs. UVB Radiation:
    • UVA rays have longer wavelengths and are recognized as a deep-penetrating radiation. Long-term exposure can damage the skin's connective tissues, leading to premature aging and playing a role in the development of skin cancer. This type of ray is used in tanning salons. UVA rays pass through window glass.
    • UVB rays have shorter wavelengths and are primarily responsible for sunburn (think B=burning rays) and skin cancer. UVB rays are blocked by window glass.

Take Cover: A Sunscreen Primer

Use the following information as a guide to help you make a quick and affordable choice for the right sunscreen for you.

  • Choosing an SPF
    Sun Protection Factor, or SPF, refers to a sunscreen's ability to protect against the burning effects of UVB radiation. The higher the SPF, the longer you can be in the sun before you burn. Hence, if you normally burn after 10 minutes, a sunscreen of SPF 15 will allow you to remain in the sun 15 times longer before burning, or 150 minutes. It is important to know that special conditions such as high altitude, tropical climates and reflective surfaces such as water, sand and snow may substantially decrease this time. For routine, daily protection, a sunscreen with SPF 15 is adequate. You may want to use a higher SPF if you are very sun-sensitive or are taking a drug that makes you burn more readily, such as tetracycline, a sulfonamide or a thiazide diuretic. Children need an SPF value of 30 to 45, since they spend more of their time in the sun. It is estimated that 80% of one's lifetime sun exposure occurs in childhood.
  • "Broad Spectrum" Sunscreens
    While UVB is responsible for the burning effects from the sun, both UVB and UVA radiation can cause skin cancer. Furthermore, UVA rays penetrate more deeply into the skin and are responsible for prematurely wrinkled, aged skin, and photosensitivity. Most products with SPF 15 or higher, and those labeled "broad spectrum," help protect against both UVA and UVB radiation. Sunblocks, which contain zinc oxide, titanium dioxide, or Parsol 1789 (methoydibenzoylmethane, also called avobenzone) reflect sunlight and also protect against both UVA and UVB rays. UVA-protective sunscreens or sun blocks are particularly important if you are in the sun for long periods of time on a daily basis, or are using a photosensitizing medication.
  • "Water-Resistant" or "Waterproof" Sunscreens
    Water is not a barrier to the sun's rays. As much as 60-80% of UV radiation is transmitted through the first 12 inches of water in a pool. Currently, the law requires products labeled waterproof need only remain on water-immersed skin for 80 minutes, while water-resistant products need to be reapplied after as little as 40 minutes. There are some products on the market that live up to their claim of all-day protection in water, but for most waterproof products, it is best to reapply them every 90 minutes if you are swimming or sweating. Reapplying sunscreen will only restore, not extend, its protection.
  • How To Use Sunscreen
    The American Academy of Dermatology suggests that, regardless of skin type, a sunscreen with SPF of at least 15 should be used year-round. Apply sunscreen generously and evenly, at least 30 minutes before going into the sun. Don't forget areas that are under sheer clothing or clothing that will be getting wet, since these conditions allow damaging rays to penetrate to the skin underneath. Sunscreen can be applied under make-up or over other medicated skin products. Avoid use of products containing Para Amino Benzoic Acid -derivatives (PABA) and discontinue use of your sunscreen if it causes redness, itching or rash; ask your pharmacist to recommend another product.

Sunglasses - For Your Eyes Only

Besides being fashionable, sunglasses serve a true function - protecting your eyes from harmful rays produced by the sun. It is as important to provide sun protection for your eyes as it is for your skin. UVB rays burn the skin and can also damage the eyes. Some research suggests that daily exposure to UVB rays over a period of many years may cause cataracts, which is a gradual clouding of the lens of the eye. UVA rays are primarily absorbed within the lens of the eye.

To best protect your eyes, look for sunglasses that provide at least 98% protection from both UVA and UVB rays. Some of the higher-priced sunglasses made with polycarbonate, glass, or plastic (CR-39) lenses can claim to block 100% of the UV rays. UV protection is transparent and completely independent of both color and color density of the lens. In other words, a darker sunglass lens does not mean more UV protection. Look for sunglasses that are labeled "UV 400," "100% UV protection," or "meets ANSI UV Requirements" (American National Standards Institute).

Related Services at Tang Center

For Students:

  • Advice Nurse: (510) 643-7197
  • Appointments: (510) 642-2000
  • Self Care Resource Center: (510) 642-7202

For Faculty and Staff:

  • Please refer questions to your health plan or primary care provider.

Additional Online Resources

Sun Safety Information

  • American Academy of Dermatology
    The American Academy of Dermatology is the largest, most influential and most representative of all dermatologic associations. With a membership of over 13,700, it represents virtually all practicing dermatologists in the United States. This website provides up-to-date patient education about UV protection at any age.
  • The Skin Cancer Foundation
    This site provides up-to-date patient information about sun safety, as well as information about prevention, diagnoses, and treatment of skin cancer.
  • kidshealth.org
    Comprehensive website for parents on how to protect your children from the damaging effects of the sun, yet still enjoy the outdoors and activities of summer.
  • American Academy of Opthalmology
    This website offers information on the ocular effects of UV exposure as well as important facts and tips on finding the right pair of sunglasses for optimum protection.
  • UV Weather Index
    This website shows the daily UV index. The UV Index is a forecast of the amount of ultraviolet expected to reach the Earth's surface when the sun is highest in the sky.

Sun Protective Clothing

Related Topics

Disclaimer: The information provided here is not intended to diagnose, treat or provide a second opinion on any health problem or disease. It is meant to support, not replace, the relationship that exists between an individual and his/her clinician.

Last reviewed: April 2005

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