UV transmission of vehicle windows

Status:

completed 06/2016

Aims:

The exposure of a vehicle's driver to ultraviolet radiation is dependent upon factors that include its transmission by the vehicle's windows. Vehicle windows exist in a range of configurations. Whereas up to the early 1990s, conventional full-glass windows were fitted, laminated products have been used since then, at least for windscreens. The plastic film used in these products absorbs a considerable proportion of the ultraviolet radiation. Besides the windows used in normal road vehicles, windows and tarpaulin canopies manufactured from plastic have also been and continue to be used in some agricultural vehicles. For investigations into cases of occupational disease, knowledge is required of the UV transmission of the vehicle windows used over the last four to five decades. As yet, no database of such data exists.

The aim of this project is to produce a register of the UV transmission properties of windows fitted to various vehicles over recent decades. This register will then be used during procedures for investigations into cases of occupational disease, and in the case history software.

Activities/Methods:

Apparatus was developed and used for measurement of the UV transmission of vehicle windows. Above all, this apparatus must not be sensitive to diffuse light entering from the side, and must permit adaptation to windows of different curvature. With the aid of the accident insurance institutions cooperating in the FB 181 large-scale research project and the scientific collection of defence engineering specimens (WTS) of the German armed forces, a large body of highly diverse vehicles was studied. In order to assure the reliability and reproducibility of the data, measurements were taken at several points on each window and repeatedly at one point. Following processing of the data, they were entered in a register.

Results:

The UV transmission of vehicle windows was measured at a number of sites, namely the scientific collection of defence engineering specimens (WTS) in Koblenz, the museum of postal vehicles in Heusenstamm, and in Ulm and Tönisforst. The multiadaptive test apparatus developed in this project was used for this purpose. The apparatus permits reproducible measurement on windows of different curvature. Three different basic window types were identified and confirmed in terms of their spectral transmission of UV radiation: laminated glass, normal glass and plastic. In order for the data to be used in prevention measures and during investigations into cases of occupational disease, a total coefficient for the UV range had to be determined from the spectral transmission that also took account of the impact of the radiation upon the skin. It was found that between five and 10% of the radiation is transmitted by full-glass windows. Laminated and plastic window products exhibited similar transmission rates of between 0.1 and 2 %.

The results are being used further in the context of prevention measures in direct conjunction with GENESIS-UV measurement results (GENeration and Extraction System for Individual expoSure). For the purpose of investigations into cases of occupational disease, these results were able to close a gap in the procedure at the statutory accident insurance institutions: time spent in vehicles had previously been assessed very inconsistently. In accordance with the current consensus, procedures were agreed based upon the data for the treatment of time spent in enclosed cabs, open cabs, and other forms of vehicle operators' stations (e. g. weather-protection canopies). They will also be considered as appropriate in the evaluation of cases of occupational disease in accordance with the Wittlich formula and radiation case history software.

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