What are sunscreens?
Sunscreens protect the skin. They play an important role in blocking ultraviolet (UV) radiation from being absorbed by the skin. UV radiation damages the skin. It can also lead to sunburns and skin cancer. But no sunscreen blocks UV radiation 100%. Sunscreens allow you to be outdoors for a longer time before your skin begins to redden. But they don't give you total protection. Using sunscreen doesn't mean you can stay out in the sun for an unlimited amount of time. Damage to your skin cells is still occurring.
What does the sun protection factor (SPF) mean?
The sun protection factor (SPF) on a sunscreen label is a measure of how well the sunscreen protects against ultraviolet B (UVB) rays. UVB rays are the main cause of sunburns. But like ultraviolet A (UVA) rays they can also contribute to skin cancer. The SPF on a label does not say anything about a sunscreen's ability to block UVA rays.
Higher SPF numbers mean greater protection from UVB rays. But no sunscreen can block all UVB rays. For example, a sunscreen with an SPF of 30 blocks about 97% of UVB rays. A sunscreen with an SPF of 50 blocks about 98% of UVB rays.
How to select a sunscreen
A sunscreen protects from sunburn and minimizes suntan by reflecting UV rays. Selecting a good sunscreen is important in protecting the skin. Choose a sunscreen that offers:
Broad-spectrum protection. This protects against both UVA and UVB rays.
An SPF of 30 or higher
Water resistance or is waterproof. This means the sunscreen provides protection while swimming or sweating for a certain amount of time—either 40 or 80 minutes, depending on the label.
The best type of sunscreen is the one you will use again and again. As long as it offers the benefits above, the type you use is your choice. Sunscreen is available in lotions, creams, gels, ointments, wax sticks, and sprays. Just be aware that different sunscreens contain different ingredients. Avoid products that have ingredients that can irritate your skin.
How to apply sunscreen
Even when they use sunscreen, most people do not apply enough of it or apply it properly, which limits how useful it is. Follow these guidelines:
Apply sunscreen to all areas of skin that will not be covered by clothing.
Use at least 1 ounce of sunscreen (enough to fill a shot glass) to cover exposed areas. An ounce should cover the whole body. But you might need to adjust the amount depending on your body size.
Apply the sunscreen to dry skin about 15 to 30 minutes before going outdoors. This gives it time to be absorbed.
Reapply sunscreen at least every 2 hours, or more often after swimming or sweating.
Protect your lips by applying a lip balm or lipstick that contains sunscreen with an SPF of 30 or higher.
Remember that children need protection from the sun, too. Sunscreens are recommended for everyone over 6 months of age. For babies younger than 6 months, the American Academy of Pediatrics approves of the use of sunscreen only if adequate clothing and shade are not available. Parents should still try to avoid sun exposure. Dress a baby in lightweight clothing that covers most surface areas of skin. But parents also may apply a small amount of sunscreen to exposed areas. These include the baby’s face and back of the hands.
Don't rely on sunscreen alone
Using sunscreen when you are going out in the sun is important. But it is only 1 part of an overall plan of protecting your skin from harmful UV rays. Other important ways to protect your skin include:
Seeking shade when appropriate. Limit your sun exposure between 10 a.m. and 4 p.m., when UV rays are the strongest.
Wearing a hat with a wide brim and tightly woven clothing that covers most of your skin, as well as sunglasses.
Avoiding tanning beds and sunlamps.