High Levels of Ultraviolet B Exposure Increase the Risk of Non-Melanoma Skin Cancer in Psoralen and Ultraviolet A-Treated Patients  Jean Lee Lim, Robert S. Stern  Journal of Investigative Dermatology  Volume 124, Issue 3, Pages 505-513 (March 2005) DOI: 10.1111/j.0022-202X.2005.23618.x Copyright © 2005 The Society for Investigative Dermatology, Inc Terms and Conditions

Figure 1 Ultraviolet B (UVB) use among cohort members over time. The histogram shows the total number of UVB treatments ever received (bars) as a function of calendar year (x-axis). The values above the bars represent the number of cohort members in that year who had a history of ever using UVB. Journal of Investigative Dermatology 2005 124, 505-513DOI: (10.1111/j.0022-202X.2005.23618.x) Copyright © 2005 The Society for Investigative Dermatology, Inc Terms and Conditions