Sun Protection Factor

• SPF stands for "Sun Protection Factor" and is the universal measurement of how long a product will protect the skin from UVB rays. According to Dr. Charles Booras at Jexmed, UVB rays "are considered the main cause of basal and squamous cell carcinomas as well as a significant cause of melanoma." Suntan lotions with larger SPF numbers will protect the skin from UVB for a longer duration.
  
  

UVA Ray Protection

• UVA rays, according to Dr. Booras, are "considered the chief culprit behind wrinkling [and] leathering" and "increase UVB's cancer causing effects." Consumers looking to protect themselves from UVA as well as UVB rays need to look beyond the SPF measurement to the ingredients list on a tube of sunscreen. Avobenzone, Mexoryl and zinc oxide are all FDA-approved ingredients that protect the skin from UVA rays.
  
  

Activity

• When deciding on a suntan lotion, it's important to determine what activities you will engage in while wearing it. If you will be swimming in salt or fresh water or participating in vigorous activity causing you to sweat, choose a sunscreen that is waterproof or water-resistant. Water-resistant sunscreens typically last up to 40 minutes in the water, while waterproof versions last about twice as long.
  
  

Considerations

• According to Amy Gates, mother and health and enviroment activist, in 2008, the Center for Disease Control released a study concluding that a common suncreen ingredient, "a chemical called oxybenzone has been linked to allergies, hormone disruption, and cell damage" and may cause cancer. Though many suntan lotions still contain this ingredient, savvy consumers may choose to avoid brands that include it.