Constituents of the stratosphere and troposphere that serve to define the solar ultraviolet spectral energy distribution that is important to the outdoor deterioration of polymer-based materials are reviewed. Particular attention is devoted to the influence of ozone ⋯ both from an historical sense, and on the basis of the latest information available on the relationship between ozone depletion and the spectral energy distribution in the so-called ozone cut-off region of the solar radiation spectrum. The significance of the historically accepted solar ultraviolet spectrum, as well as that predicted on the basis of, for example, 10 and 20% decreases in total column ozone, are discussed in terms of [1] correctly measuring ultraviolet radiation in the spectral region of importance to materials, [2] assessing the effects of solar ultraviolet radiation on such materials, and [3] simulating the spectral energy distribution of solar ultraviolet radiation in indoor exposure test scenarios.