The sun, which radiates ultraviolet (UV) rays, sends out UVA and UVB rays. UVA rays are the weakest rays, and cause long-term damage to the skin, like wrinkles. However, 95% of UV radiation from the sun that reaches the earth is UVA rays. UVB rays, which are stronger, cause sunburn, and most skin cancers. UV radiation is linked to developing skin cancer, and the following conditions influence the risk of UV radiation.
Conditions that Determine the Degree of Exposure from the Sun
- Time of day – Seventy-five percent (75%) of UV rays come down to the earth in the 8-hour period between 9 am and 5 pm. However, the especially dangerous period is the 4-hour period between 10 am and 2 pm, when one-third of all UV rays come down.
- Season of the year – UV rays are strongest during the summer.
- Clouds – While the extent to which UV rays get through the clouds varies, even on cloudy days, up to 80% of the sun’s harmful UV rays can penetrate your skin.
- Altitude – People who reside or work at higher elevations get sunburn more easily because they are exposed to more UV rays.
- Reflection from some surfaces – UV rays bounce off such surfaces as water, sand and snow, causing increased exposure to UV rays.
Link Between UV Radiation and Cancer
Most skin cancers result from exposure to the UV rays in the sunlight, and it is estimated that about 1 in 5 Americans develops skin cancer. The two most common types of skin cancer are basal cell cancer, and squamous cell cancer, both of which usually occur in parts of the body that are exposed to the sun. A third kind of skin cancer related to sun exposure is melanoma.
1. Although there is an increased risk of skin cancer among fair skinned persons with freckles, even persons with dark skin get skin cancer from excess exposure to sun rays.
2. In addition to sun exposure, UV rays can do great damage from tanning beds or booths.
Other UV Radiation Health Problems
UV rays can also cause eye problems by inflamed or burned corneas, the front of the eye. UV rays can also weaken the immune system, thus increasing the risk of infection.
Ways to Protect the Skin from the Sun
- Spend most of your outdoor time in the shade
- Sunscreen needs to be reapplied every 2 hours, and more often after swimming, heavy sweating, and toweling off.
- When you are in the sun, protect your skin with clothing and/or sunscreen on uncovered skin areas
- Wear a wide brim hat and sunglasses
- About sunscreens: Sunscreens are creams, lotions and sprays with high sun protection factor (SPF)ratings. While many products have labels with very high SPF ratings, most are little or no better than a product with an SPF of 30. That’s because an SPF product of 30 already blocks 97% of UVB rays.
The American Academy of Dermatology (AAD) gives the following recommendations about sunscreens:
Everyone should use sunscreen that offers the following:
- Broad-spectrum protection (protects against UVA and UVB rays)
- Sun Protection Factor (SPF) 30 or higher
- Water resistance
A sunscreen that offers the above helps to protect your skin from sunburn, early skin aging3 and skin cancer.
Other American Academy of Dermatology Recommendations for Skin Protection and Health
- Seek shade when appropriate, remembering that the sun’s rays are strongest between 10 a.m. and 2 p.m. If your shadow is shorter than you are, seek shade.
- Wear protective clothing, such as a long-sleeved shirt, pants, a wide-brimmed hat and sunglasses, when possible.
- Use extra caution near water, sand and snow, as they reflect the damaging rays of the sun, which can increase your chance of sunburn.
- Get vitamin D safely through a healthy diet that may include vitamin supplements. Don’t seek the sun.
- Avoid tanning beds Ultraviolet light from the sun and tanning beds can cause skin cancer and wrinkling. If you want to look tan, you may wish to use a self-tanning product, but continue to use sunscreen with it.6
- Check your birthday suit on your birthday. If you notice anything changing, itching or bleeding on your skin, see a board-certified dermatologist. Skin cancer is very treatable when caught early.
Enjoy your summer and other outdoor time, and check out our other Summer Tip Sheets including:
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