The heat of the summer is upon us, and while we should be mindful of sun protection year-round, this is the season of beach vacations, backyard barbecues and other activities that can keep you in the sun for long periods of time. While the Earth’s atmosphere blocks most of the sun’s UV radiation from reaching us, the small amount that does get through is associated with a variety of health problems ranging from sunburn and premature aging to cataracts and skin cancer. Using sunscreen is an important way to protect your skin from the sun’s harmful UV rays.

What does an SPF number tell me?

SPF stands for Sun Protection Factor. It measures the level of protection from UVB rays — the type of radiation that causes sunburns and skin cancer — a product will give you. It indicates the length of time that your skin is protected from sunburn while wearing it compared to the time it takes you to burn without it.

For example, if you have very fair skin and tend to start getting burned after five minutes in the sun without any sunscreen, properly applying a sunscreen with an SPF of 30 would protect you for 30 times five minutes (or 150 minutes) before you begin to burn. Your level of sun protection can also be influenced by other factors, such as the weather conditions, your location, your skin type and if you’re swimming or sweating.

Selecting an SPF

SPF is indicated by a number that ranges from 1 to 100. Generally speaking, a higher SPF extends the amount of time you can spend in the sun while protecting your skin.

SPFs are categorized into four levels: low (4, 6, 8, 10); medium or moderate (15, 20, 25); high (30, 40, 50); and very high (50+).

Depending on your skin type, dermatologists recommend using a sunscreen with an SPF of at least 30, which blocks 97 percent of the sun’s UVB rays. Higher SPFs block a bit more of the sun’s UVB rays, but no sunscreen — not even SPF 100 products — can block all the sun’s rays.

It’s important to remember that sunscreens with high SPFs work for the same amount of time as those with lower SPFs, and do not allow you to spend additional time outdoors without reapplication. All sunscreens should be reapplied approximately every two hours when outdoors and after swimming or sweating, according to the directions on the bottle.

Take extra precautions

In addition to using sunscreen with 30 SPF or higher, the American Academy of Dermatology also advises using one with broad-spectrum protection to guard against UVB rays as well as UVA rays, which penetrate deep into the skin and cause aging and immune suppression.

However, sunscreen alone cannot fully protect you, which is why dermatologists suggest taking the following steps to further protect your skin and discover skin cancer as early as possible:

  • Wear sunglasses with both UVA and UVB protection.
  • Seek shade when the sun’s rays are the strongest — between the hours of 10 a.m. and 4 p.m.
  • Wear a wide-brim hat and sun-protective clothing.
  • Use a lip balm with SPF 30 or higher.
  • Keep infants out of the sun.
  • Perform a head-to-toe self-examination of your skin at least once a month.
  • See your physician every year for a professional skin exam.

Dr. Suneeta Walia is a native of New Orleans and completed her undergraduate studies at Louisiana State University. She earned her medical degree from Louisiana State University in New Orleans in 2001. Dr. Walia completed her internship at Georgetown University and her dermatology residency at George Washington University in Washington D.C. She also completed a Mohs Surgery fellowship at Dermatologic Surgery Specialists in Macon, Georgia. Dr. Walia is board certified by the American Board of Dermatology. She is an active member of the American Academy of Dermatology, the American Society for Dermatologic Surgery and the American College of Mohs Surgery. Her areas of interest include Mohs Micrographic Surgery, dermatologic surgery and skin cancer. Dr. Walia sees patients at Ochsner Medical Center – Jefferson Highway (1514 Jefferson Highway New Orleans, LA 70121).