To examine during what behaviors people apply sunscreen and to assess the relationship to UV exposure monitored by personal dosimetry and diaries.
Open prospective observational study.
A convenience sample of 340 Danish volunteers: children, adolescents, indoor workers, sun worshippers, golfers, and gardeners (age range, 4-68 years).
Subjects recorded sunscreen use and sun-exposure behavior in diaries and carried personal, electronic UV dosimeters, measuring time-stamped UV doses continuously, during a median of 119 days covering 346 sun-years (1 sun-year equals 1 subject participating during 1 summer season).
Main Outcome Measures
Associations between sunscreen use and age, sex, skin type, occupation, sunburn, UV exposure doses, and behavior; and adequate application density and sun protection factor required to prevent sunburn.
There were great variations in sunscreen use, which was highly correlated with risk behavior (sunbathing or exposing the upper body) (r = 0.39; P<.001). Sunscreens were used on a median of 5 days per sun-year (range, 1 day for gardeners to 16 days for sun worshippers). Ten percent of females and 41% of males never used sunscreens. Females used sunscreens more but also had more unprotected risk behavior than males (8 days vs 4 days; P<.001). Sunscreen use was not correlated with age, and children had as much unprotected risk behavior as adults. Sunscreens were used on 86% of the days with risk behavior in southern Europe vs 20% in northern Europe (P<.001). The UV doses were significantly higher on days with sunscreen (P≤.03) and on sunburn days (P<.001). The median sun protection factor was 10.5. The sun-protecting effect corresponded to an application density of 0.5 mg/cm2.
Days with sunscreen correlated not with days without risk behavior, but with days “sunbathing with the intention to tan,” indicating that sunscreens were used as tanning aids to avoid sunburn.