Your Health: A little sun protection goes a long way

Summer is here, and many of us are exposed to an abundance of sunshine. I’d like to explain how we can best avoid the harmful effects of the sun.
We all know the sun provides visible light to our earth, but it also produces invisible light called ultraviolet rays, of which there are two types. Ultraviolet A causes skin aging and skin cancer, not visual sunburn. Ultraviolet B is what causes the traditional sunburn. The sun’s rays are strongest between 10 a.m. and 4 p.m.
Some people are more sensitive to the damaging effects of the sun. Those who have blond or red hair, light-colored skin and light-colored eyes will get sunburn more quickly than those with darker skin and eyes.
Sunlight damages the skin in the same manner as a heat burn, causing symptoms ranging from a first-degree red, hot, painful burn to a second-degree burn that causes blisters and deeper damage to the skin. Unprotected long-term exposure to sunlight will cause wrinkling of the skin, with the appearance of premature aging. The most serious result of sun damage is the increased chance of developing a deadly skin cancer called melanoma.
The best protection against damage caused by the sun is to keep your skin covered by clothing to the greatest extent possible. Wear light-colored, tightly woven clothing. If this is impractical, then a sunscreen lotion is necessary.
Sunscreens are rated by a code called SPF, sun protection factor, which you will see on the label of all sunscreens. It rates how long a person can be in the sun without being burned. There is no proof that SPF ratings higher than 30 give any measurable benefit. Most sunscreens now protect against both UVA and UVB, but check the label before you buy a sunscreen lotion.
I also recommend buying new sunscreen at the beginning of each summer, as last year’s might have lost its potency.
Proper application is the key to success. Apply sunscreen at least 20 minutes before you go out into the sun. Use about 1 teaspoon per body part, such as the face, an arm or a leg. Use a total of about 2 tablespoons (comparable to what would fill a shot glass) to cover the body when wearing a bathing suit.
Most sunscreen lotions are labeled either “waterproof” or “water-resistant.” Even these must be reapplied after swimming, towel drying or heavy sweating. Read the directions on the label.
Apply the sunscreen to all exposed body parts, especially those often overlooked, such as tops of ears and feet, the back of the neck, the face and bald spots.
In summary, remember the following recommendations:
**Avoid sun exposure, especially between the hours of 10 a.m. and 4 p.m.
**Always wear sunscreen, and reapply frequently — every two to three hours, or more often if your skin gets wet from swimming or sweating. One application in the morning will not protect you through the whole day.
**Keep yourself covered with light-colored, tightly knit clothing as much as possible.
**Avoid tanning salons.
**See your doctor if you have a sunburn and experience unbearable pain or significant blistering.
**Check your skin (all areas) regularly for any unusual dark lesions.
**Protect your eyes with UV-rated sunglasses.
Have a healthy, happy summer!
Terry Hollenbeck, M.D., is an urgent-care physician at the Palo Alto Medical Foundation Santa Cruz in Scotts Valley.  A doctor with 36 years’ experience, he invites readers to view his previous columns at his website, valleydoctor.wordpress.com, or e-mail him at va**********@sb*******.net. Information in this column is not intended to replace advice from your own health care professional.  For any medical concern, consult your own doctor.