Ultraviolet radiation can cause photochemical and photobiological damage in plants, animals, and humans. As a consequence of ozone depletion, an increase in solar ultraviolet radiation is expected in outdoor environments. However, there is very little quantitative data on it. We measured solar ultraviolet-B and ultraviolet-A irradiances in typical outdoor environments (concrete, grass, sand, soil, and snow) at a height of 150cm (the average height of a Japanese adult's face) at various local standard times with solar elevations ranging from about 30deg; to 75deg; from the horizon. In each environment, measurements were taken for six directions relative to the sun: direct, overhead, front, side, back, and downward. Solar UV-B and UV-A irradiances in four of the outdoor environments (concrete, grass, sand, and soil) showed similar distribution patterns in each of the six directions, although snow gave extremely large reflection. In addition, solar UV-B and UV-A irradiances were measured in and near the shade of a tree, and on a person's cap or hat. In all cases, we found that solar elevation and direction to the sun are major factors in protection from solar ultraviolet radiation.
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