Sun Protection Simplified
Published by Contra Costa Times
Posted on Wed., June 17, 2009
By Sonika Shah, M.D.
MRS. BIRDIE, an avid golfer, was shocked to learn that the rough patches on her face and arms were not only pre-cancerous but also the result of decades of sun exposure. She, like many, believed her darker skin tone protected her.
Sun exposure is the most preventable risk factor for all skin cancers, including the most deadly form: malignant melanoma. However, you can still have fun in the sun while lowering your risk of skin cancer.
Sunlight contains two types of harmful ultraviolet rays: UVA and UVB. UVA rays, which pass through window glass, comprise 98.7% of the ultraviolet radiation that reaches Earth's surface. Thought of as the sun's aging rays, UVA rays cause wrinkling and age spots as well as weaken the immune system. UVB rays, the sun's burning rays, which are blocked by window glass, are the primary cause of sunburns. Both UVA and UVB radiation can cause skin cancer. A tan is the skin's response to injury caused by UV radiation, both natural and artificial. Unfortunately, there is no safe way to tan.
Clothes are your best form of protection from the sun. Wear light-colored, long-sleeved clothing, a wide-brimmed hat and UV light-blocking sunglasses, ideally, ones that wrap around the sides of the eyes. Most fabrics that are not see-through provide reasonable protection, but the new microfiber nylons are very sun protective.
Sun Protection Factor (SPF) is a rating based on UVB blocking ability. The higher the SPF, the greater the protection from UVB rays, but not proportionately. For example, SPF 15 screens 93% of UVB rays, while SPF 30 screens 97% of UVB rays. Think of SPF as a time multiplier; i.e. if a person typically burns in 10 minutes, using an SPF of 15 means that it would take 15 times longer to burn, in this case 150 minutes. Dermatologists recommend a sunscreen and lip balm with SPF 30 or higher.
Most people only apply 20-60% of the amount of sunscreen required to obtain the labeled SPF rating. It takes at least 1 ounce (about the amount to fill a shot glass) to cover an average adult.
To achieve the SPF factor labeled, you will need:
Remember the word "BLOCKED" to be sun smart:
Dr. Shah is a board-certified internist affiliated with Contra Costa Regional Medical Center in Martinez. Healthy Outlook is written by the professional staff of Contra Costa Health Services, the county health department. Send questions to series coordinator Dr. David Pepper at email@example.com. For more health information, go to www.cchealth.org.