As summer begins and people spend more time outdoors, the Skin Cancer Foundation reminds everyone how to use sunscreen safely and effectively as part of a sun protection routine. Although no single sun protection method is foolproof, research has shown that not only does daily sunscreen use reduce skin cancer risk, but it also helps prevent premature skin aging caused by ultraviolet (UV) rays from the sun.

Selecting a sunscreen can seem overwhelming. There are many different formulations, and language on product packaging may be unfamiliar. Deciphering a sunscreen's label is the first step to choosing the perfect product.

The first thing to consider is the sunscreen's sun protection factor (SPF). One way to think about SPF is in terms of percentages. SPF 15 filters out approximately 93% of all incoming ultraviolet B (UVB) rays. SPF 30 keeps out 97%, and SPF 50 keeps out 98%. A sunscreen with a minimum of SPF 15 may be fine for days that a person is mostly inside, but those who are planning to spend an extended amount of time outdoors should pick a water-resistant formula with an SPF of at least 30.

The second thing to check for on a label is the term "broad spectrum." It's vital that a sunscreen offers broad-spectrum protection, which means the product protects against both ultraviolet A (UVA) and UVB rays. Both types of UV rays penetrate the skin and cause damage that can lead to skin cancer.

Once a person has decided on his or her SPF and checked that a product has broad-spectrum protection, he or she can decide on other qualities based on personal preference and lifestyle. For example, check the list of active ingredients on the bottle. For those with sensitive skin, look for a physical filter like zinc oxide or titanium dioxide. These substances are less likely to cause skin reactions than chemical ingredients. Many sunscreens combine both chemical and physical filters.

People can also look for the formulation and product "feel" that is right for them. There are quality sunscreen options available in lotions, gels, sticks and sprays. Many offer tinting, antiaging ingredients, dry "sports" feel or benefits for acne-prone skin. There are now many skin care items like serums and moisturizers that include UV filters as well. The most important thing is using the product correctly.

After selecting an appropriate SPF and choosing a broad-spectrum formula, understanding application is a must. Use one ounce of sunscreen, about the amount that would fit into a shot glass, to cover the entire body. For the face, a nickel-sized dollop works. Slathering on sunscreen in the morning is not enough to protect a person all day, though. The Skin Cancer Foundation recommends applying sunscreen 30 minutes before going outside, then reapplying every two hours and immediately after swimming or sweating. Water-resistant sunscreens typically offer 40 minutes or 80 minutes of protection when in the water. No sunscreen is truly waterproof, however, so in these situations, be aware of how long the product claims to protect against moisture, and keep an eye on the clock. With reapplication, a person should use up one four-ounce bottle of sunscreen during a full day outdoors.

To find products that have earned the Skin Cancer Foundation's Seal of Recommendation for safe and effective sun protection, visit http://www.SkinCancer.org/recommended-products.

No single sun protection method can protect someone completely. The Skin Cancer Foundation has always recommended a multi-pronged approach to sun safety. While using sunscreen is a crucial part of any sun protection routine, it is also important to seek shade and cover up with clothing, including a wide-brimmed hat and UV-blocking sunglasses.