Sunscreen sun protection factor (SPF): Is higher better?

The harmful properties of sunlight are well known. Actinic keratoses occur nearly exclusively in chronically sun exposed skin. Nonmelanoma skin cancer, especially squamous cell carcinoma, is strongly linked to sun exposure. The International Agency for Research on Cancer (IARC) of the World Health Organization classifies sunlight as a Group I carcinogen.1 Sun exposure is also strongly associated with photoaging. It is estimated that 80% or more of the changes in the skin that occur over time are due to the extrinsic effects of sunlight.