2. You don’t really know what SPF means.
SPF stands for Sun Protection Factor. Basically it’s a measurement of how long you can expose your skin to sunlight before burning. Without sunscreen, a person with a medium complexion can begin to burn after only 10 minutes of exposure. With an SPF 30, you would multiply 10 minutes by 30, extending your time before burning to 300 minutes. Those with fair skin or previous sun damage will have a much shorter exposure time.

3. You’re forgetting about your hands.
You should use sunscreen all over—particularly on your face. But don’t forget about your hands which often get the most daily sun exposure. Nothing ages you like wrinkled hands . So if you don’t want to see grandma’s hands coming out of your sleeves, lather on the sunscreen.

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