Global mean erythemal UVR daily dose (J/m2) during 2011-2012, based on data from the Ozone Monitoring Instrument on the National Aeronautics and Space Administration's Aura satellite as cited in Levelt et al.6 In addition to personal behaviors such as the amount of time spent outside and use of sun-protective clothing, ambient UVR is an important consideration in estimating UVR exposure histories because of its substantial variation by geographical location. Figure created by Dr Douglas C. Morton (NASA’s Goddard Space Flight Center, Greenbelt).