Article contributed by: Holly McCoppin, MD, dermatologist with College Park Family Care Center


We all see this on our sunscreen labels but what does it actually mean? SPF stands for Sun Protection Factor. SPF represents the amount of protection the sunscreen provides from UVB rays. So the number indicates the strength of protection. For instance, using an SPF 30 sunscreen theoretically prevents reddening/sunburn 30 times longer.

UVA rays (aging rays) can prematurely age your skin, causing wrinkles and age spots. They can pass through window glass. UVB rays (burning rays) are the primary cause of sunburn. They are blocked by window glass.

The sun emits harmful UV rays year-round. Even on cloudy days, UV rays can penetrate the skin. Broad-Spectrum indicates that the sunscreen provides protections from both UVA and UVB rays.

What to Look for in a Sunscreen

The US Food and Drug Administration (FDA) requires sunscreen labels to provide consumers with information about whether a sunscreen will protect against skin cancer in addition to sunburn. Labels also indicate whether the product is water-resistant.

The best sunscreen is one you will use again and again. The kind of sunscreen selected is a matter of personal choice and may vary depending on the area of the body to be protected. Some sunscreen products are also available in moisturizers and cosmetics. While these products are convenient, they also need to be reapplied in order to achieve the best sun protection.

Sunscreen also may be available in combination with an insect repellant. I recommend these products be purchased and used separately.

I always recommend to my patients a broad-spectrum, water-resistant sunscreen with a Sun Protection Factor (SPF) of at least 30 to all exposed skin every day.

How to Use Sunscreen

  • Use enough sunscreen to generously coat all skin that will not be covered by clothing.
  • Apply sunscreen to dry skin 15 minutes prior to going outdoors.
  • 1 ounce, enough to fill a shot glass, is considered the amount needed to cover the exposed areas of the average adult body.  Adjust the amount of sunscreen applied depending on body size.
  • Skin cancer can form on the lips, as well, so apply a lip balm or lipstick that contains sunscreen with an SPF of 30 or higher.

Skin Cancer & the Sun

One in five Americans will develop some form of skin cancer during their lifetime. Sun exposure is the most preventable risk factor for skin cancer, including melanoma, the deadliest form of skin cancer. To protect your skin from the sun, seek shade, wear protective clothing and apply sunscreen. Check your skin and see a dermatologist if you notice anything changing, itching or bleeding.