Before you park yourself poolside, how much do you really know about sun exposure? Let's find out with a quick True or False quiz: First, True or False: You get 80 percent of your lifetime sun exposure before you're 18. That's FALSE. According to the Skin Cancer Foundation, by age 18 you get less than one-quarter of your lifetime sun exposure. In fact, you accumulate about half of it between ages 20 and 40 - more than any other time of your life. Five minutes of sun here and there adds up - increasing your risk of skin cancer and wrinkles. Next, True or False: You use a moisturizer with an SPF, so you don't need sunscreen. That's also FALSE. SPF measures only the protection you get from UVB rays - not UVA, which penetrate your skin more deeply. A lot of moisturizers don't effectively block UVA rays. In fact, in a study of moisturizers containing SPF, only one in five protect you from UVA rays. True or False: A sunscreen with SPF 100 gives you complete protection compared to say a sunscreen with SPF 30. That's FALSE. The difference between an SPF rating of 30 and an SPF rating of 100 is very small. SPF stands for Sun Protection Factor and it represents the difference in time it takes a person to burn with sunscreen, compared to the time it would take for them to burn without it. In other words: A higher SPF isn't like adding another layer of clothing to give you more protection. It's simply giving you the same protection for a longer amount of time. One final True or False: Tanning beds are safer than the sun. That's FALSE. Studies show that tanning bed bulbs emit up to 10 times more wrinkle and cancer-causing UVA rays than the sun. So 20 minutes of indoor tanning is three times as bad as an hour outdoors. To be clear - anything, the sun or a machine, that gives you a tan, changes your DNA, which can lead to skin cancer.