There are several things to keep in mind when choosing which sunscreen to use and specifically which SPF (or Sun Protection Factor) is right for you. The FDA says SPF is related to the amount of solar exposure you get. Therefore the ideal SPF may differ depending on skin tone, the time of day, the amount of sunscreen you put on, and the amount of times you reapply.

A lighter skin tone means you absorb more sun and need more protection.

The hours in the middle of the day (typically 10am-4pm) have a more intense solar exposure so this is when you will need more protection compared to the early morning or evening hours.

The FDA says the higher the SPF values the better protection you will receive. Many sources, including the CDC and the FDA, recommend applying SPF 15 or above. The American Academy of Dermatology recommends SPF 30 or above.

According to the CDC most people apply less sunscreen than recommended -- about a quarter to half of what is needed.

A study was conducted in a controlled environment by the CDC that showed higher SPF levels only showed a difference of 2-4 percent of additional protection. A Mayo Clinic study suggested the difference between SPF 15 and 30 is not double the protection, but rather it is just slightly better.

SPF values below 15 has only been shown to prevent sun burns, not necessarily fight against early skin aging or skin cancer. They do not protect against both UVB and UVA rays.

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