Several factors of various type can influence solar UV exposure of Outdoor Workers (OWs). A significant part of the solar UV is absorbed by stratospheric ozone layer, so the reduction of the ozone layer, that is currently ongoing, is progressively increasing the amount of UV reaching the earth surface and, consequently, the worker's exposure.
Among other, main relevance have geographical factors and first of all the latitude and also the altitude. Furthermore, as UV exposure varies with the elevation angle of the Sun above the horizon, exposure depends on the season and month of the year and hour of the day, being maximal between 11 a.m. and 3 p.m. about. Meteorological factors as clouds have an obvious relevance, but a variable proportion of UV, up to the 90%, can penetrate light clouds. Atmospheric composition/pollution has a variable effect, as suspended particles can absorb or reflect/refract/diffuse UV rays.
Different working factors can significantly interfere with UV exposure in OWs, as the surfaces surrounding the area of work: e.g. fresh snow or metals, especially if polished, reflects a high proportion of UV, while green grass absorbs up to the 98–99%. Working postures can significantly modify the exposure of different parts of the body during outdoor activities. Other occupational factors include the presence of UV shelters, like roofing or vegetation. The organization of task is also important: e.g. activities avoiding direct exposure during the central hours of the day, and work breaks, as meals, in UV protected environments are highly effective to reduce exposure. Other important working factors are the use of sunglasses with adequate UV filtering lenses, brimmed hats, UV absorbing cloths and a correct use of sunscreens SPF≥30. A last individual factor that cannot be ignored is the role of personal protective behaviours of the worker, as habits to seek the sun.