August 23, 2016
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Sunburn and Sun Poisoning (cont.)

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What is SPF?

SPF, or Sun Protection Factor, is the measurement of how well an agent may protect against sunburn. SPF can be calculated from the amount of time it takes to develop mild redness or burning in an unprotected person. For example, if someone develops mild sunburn-related redness in 20 minutes, he or she may develop the same degree of redness in 300 minutes (5 hours) with an SPF 15 sunscreen (15 multiplied by 20 minutes) when properly applied.

Traditionally, the SPF is rated for sun damage by UVB rays only. A regulation by the Food and Drug Administration (FDA) in 2012 required the industry to change their labels to also include "broad spectrum" label information on protective potential against UVA radiation. This change is very important because UVA is responsible for a significant portion of sun damage to people. The labeling provisions include:

  • Sunscreen products that are not "broad spectrum" with SPF values from 2 to 14 will be labeled with a warning that reads: "Skin Cancer/Skin Aging Alert."
  • Water resistant sunscreen claims must have information in regard to how much time a person can expect to have the declared SPF level of protection while sweating or swimming.. Two times will be permitted on the labels: 40 or 80 minutes.
  • Manufactures can no longer make claims that sunscreens are "waterproof" or "sweatproof" or identify their products as "sunblocks."
  • Sunscreens cannot claim protection immediately on application (for example, "instant protection") or protection for more than two hours without reapplication.

What is the best way to apply sunscreen?

Apply sunscreen 15 to 30 minutes before expected sun exposure. Reapplication of sunscreen every 1 to 2 hours is also advised. Some experts encourage more frequent reapplication, especially shortly after initial exposure. It is also important to apply sunscreen liberally; spreading the product too thin may not achieve the desired degree of protection. A general recommendation is to apply an amount similar to the size of a golf ball for a person of average build.

Sunscreen sprays also are becoming more available and popular. They are generally effective; however, some questions have been raised in regard to the amount of spray that actually adheres to the body once applied. The spray can be dispersed by wind, an insufficient amount may be sprayed, or the sunscreen may be sprayed too far from the body. It is recommended that sunscreen sprays be used in conjunction with other more traditional topical sunscreens for the best sun protection. There also are concerns about the amount of sunscreen that may be inhaled unintentionally, and if that poses any health risks.

SPF 15 sunscreen is the minimum requirement for most individuals. Stronger sunscreens are recommended for people who easily burn in the sun and have longer exposure time in the sun. Water exposure may wash off the sunscreen so it should be reapplied after the body dries up.

Medically Reviewed by a Doctor on 6/17/2015


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