A small but measurable component of some indoor lighting is ultraviolet radiation (UVR); whether it is sufficient to modify the indoor worker's risk for chronic skin changes is not directly answerable with available technology. A first approach to this question involves a) estimating a range of annual background solar exposure for indoor workers currently at risk; b) determining whether, and at what levels, UVR exposure is a part of specified indoor lighting; and c) calculating the increment in risk implied by a and b. This algorithm predicts that some lighting conditions that meet NIOSH recommended standards would still result in significant increases in the risk of cumulative UVR damage, including skin cancer. More information concerning actual exposure conditions, the relation of spectral effectiveness for luminosity and UVR production, and dose-time reciprocity are required to improve our predictions of long-term cutaneous effects of indoor lighting.