Long-term exposure to low levels of ambient UVB are associated with a decreased risk of moderate-to-severe acne: A retrospective cohort study in college students.

BACKGROUND

As a crucial component of solar radiation, the association between exposure to ambient ultraviolet (UV) radiation and acne remains unclear.

METHODS

This was a multicenter retrospective cohort study of incoming college students in five universities of China. Previous exposure (6 years prior to enrollment) to different wavelengths of ambient UVs were obtained from public repositories by linking to individual hometown addresses. Logistic models were applied to assess the relationship between ambient UV exposure and acne. Subgroup analysis was conducted by sun protection behaviors and time of daily sun exposure. Overall effect and single effect of exposure to four different wavelengths of UVs (305, 310, 324, and 380 nm) were estimated by Bayesian kernel machine regression (BKMR).

RESULTS

A total of 19,939 participants was included for analysis. Analysis in all participants showed a significant association between log-transformation levels of exposure to UV at 305 nm (log (UV 305 nm)) and acne (OR = 0.77, p = .021). The effect size was stronger in participants reporting no sun protection habit. Both UVs at 305 nm (OR = 0.51, p = .001) and 310 nm (OR = 0.50, p = .012) were associated a decreased risk of acne in participants reporting no sun protection habit. This inverse association was also observed in those exposed to low levels of UV (<1 h/day). The BKMR indicated consistent results that low levels of exposure to UVs combination and UVs at 305 and 310 nm were associated with a lower risk of acne.

CONCLUSION

Long-term exposure to relatively low levels of ambient UVB are associated with a decreased risk of moderate-to-severe acne in college students.