Making Sense of Sunscreen Products

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Most people are understandably confused when it comes to choosing a sunscreen because of the baffling array of available choices. Common questions about sunscreens include the following:

  • What is SPF? How high should the SPF be?
  • Should a sunscreen block UVA or UVB radiation?
  • Does it matter whether it is a gel, cream, or spray?
  • Should it be water-resistant?

SPF stands for sun protection factor. These numbers refer to the product's ability to screen or block out the sun's burning rays. The SPF rating is calculated by comparing the amount of time needed to produce sunburn on protected skin to the amount of time needed to cause a sunburn on unprotected skin. The higher the SPF, the greater the sun protection. The U.S. FDA recommends that the maximum SPF value on sunscreen labels be "50 +" because many scientists believe that there is insufficient evidence to show that products with SPF values higher than 50 provide greater protection for users than products with SPF values of 50.

However, it is a common mistake to assume that the duration of effectiveness of a sunscreen can be calculated simply by multiplying the SPF by the length of time it takes for him or her to suffer a burn without sunscreen, because the amount of sun exposure a person receives is dependent upon more than just the length of time spent in the sun. The amount of sun exposure depends upon a number of factors, including the length of exposure, time of day, season, geographic location, and weather conditions.