This information comes from dummies.com (it will help us understand the differences between chemical and physical sunscreens)!

Sorting Out Sunscreens for Healthy Sun Protection

The only thing more blinding than the sun is the number of sunscreens on the market. Trying to make sense of sun protection factors, UVA and UVB blocks, waterproof versus regular, and so on can leave your head spinning.

But if you take a few minutes to sort out the facts about sunscreens now, you’ll be able to pick a product that will do the best job of protecting your skin from the sun’s powerful rays — along with reducing the potential for deadly skin cancers.

Sunscreens keep damage away so you can go outside and play

Sunscreens contain ingredients that keep the sun’s ultraviolet rays (UVA and UVB) from penetrating your skin. Too much exposure to UVA and UVB rays will cause your skin to burn, age prematurely, and develop cancer.

UVAs penetrate the skin more deeply than UVB rays. UVAs give your skin that weathered, wrinkled, leathery look. UVBs burn your skin. Both types cause skin cancer.

The SPF (sun protection factor) number you see on a bottle of sunscreen tells you how effectively that product will block UVB rays, not how many hours you can stay in the sun without getting burned. For instance, an SPF 15 sunscreen will filter out 93 percent of UVBs. An SPF 30 sunscreen means you’ll be protected from 97 percent of these rays. If you have very light skin you might benefit a bit more from a higher SPF, but no sunscreen will block 100 percent of UVB rays.

Interestingly, the SPF doesn’t address wrinkle-causing UVA protection at all. As a matter of fact, some sunscreens only filter UVB rays. To make sure the sunscreen you’re buying will block UVA rays too, look for the words “broad spectrum” on the bottle.

If you know most of your day will be spent in the office except for a short parking-lot commute, a sunscreen with an SPF 15 may be all the protection you need. Then, when Saturday rolls around and you’re ready to golf or enjoy an outdoor concert, slather on a broad spectrum sunscreen of SPF 30 or higher.

Pick toiletries that perform double duty. Some aftershaves and many foundations and moisturizers already contain sunscreen. Using one product instead of two can save you time and money.

Let’s get physical, or chemical, for sun protection

Sunscreens work by providing either physical or chemical protection from UV rays. The ingredients and properties of these two types of sunscreens differ and you may discover you prefer one kind over the other.

Physical types have ingredients such as zinc oxide and titanium dioxide that shield your skin from damaging rays. In the past, these were the thick, white creams you’d see on the noses of lifeguards. Newer formulations are more transparent and some even come in bright colors that kids enjoy wearing.

If you’re very sensitive to ultraviolet radiation, physical sunscreens might work better for you since they sit on the skin and deflect rays before your skin can absorb them.

Chemical sunscreens filter out UV rays as they begin to penetrate your skin. Unlike physical sunscreens, chemical formulations are thin and colorless. Look for ingredients such as avobenzone and oxybenzone if you want to make sure you’re getting the chemical type.

Apply sunscreen 30 minutes before going outside so your skin has time to absorb its protective properties. Reapply every two hours to ensure continued effectiveness. If you’re sweating a lot or in and out of the water, reapply as soon as you’ve dried off.

Special sunscreen rules for water and little waders

There’s no such thing as a waterproof sunscreen. However, If you go for a swim or work up a sweat, a water resistant sunscreen won’t wash off (or drip in your face) as easily as another type of sun protection. However, you’ll still need to reapply a water resistant sunscreen every couple of hours, or as soon as you come out of the water or towel off.

All children older than 6 months should wear a broad-spectrum sunscreen with an SPF of at least 30 every time they’re outdoors. Babies have particularly delicate skin and need extra protection from the sun. Keep them out of direct sunlight and make sure their skin is covered with a hat and clothes. Ask your doctor before applying sunscreen to any baby younger than 6 months.