The long days of summer mean hot weather and the need for more sun protection. Sunscreen protects our skin by either physically deflecting UV rays' active ingredients or chemically with carbon-based compounds. When choosing a sunscreen we must compare application method, the SPF, and the active ingredients.

In TED-Ed's latest video, "Which Sunscreen Should You Choose?", host Mary Poffenroth explains the many forms of sunscreen impact our body and the environment in their own way. For example, sprays are convenient to put on, especially when we're wet, but science has found most people don't apply a thick enough layer to get full protection. Inhaling the spray chemicals also come with several health risks.

Rather, a lotion bottle with an SPF of at least 15 is recommended, although 30 is better. SPF 15 blocks 93 percent of UVB rays, SPF 30 blocks 97 percent, and SPF 50 blocks 98 percent. This is based on the quantity of solar exposure. Genetics, when, where, and how you spend your time in the sun will determine how much time we have before we burn.

Sun protection factor measures a sunscreen's ability to filter UVB rays, linked to sunburn and skin cancer. However, SPF only measures UVB rays, and doesn't protect from UVA rays. Unlike UVB, UVA is not filtered by the ozone at all and doesn't cause sunburn, but it can lead to darkening and aging because of its ability to penetrate deeper into the skin. A way to tell if your sunscreen protects against UVA rays is if it includes the words "broad spectrum" — the most important thing to look for on a sunscreen label.

When reading a lotion label, remember SPF is in the front, and on the back are the active ingredients like zinc oxide, or titanium dioxide, or carbon-based chemicals, such as oxybenzone, butylparaben, 4MBC, and octinoxate.

Taking the time to read the label could make a difference between getting a tan and getting sunburn.