Software tools are increasingly used to assess the exposure of workers to hazardous substances. The absorbed dose is estimated on the basis of diverse models. For inhalation exposure and dermal exposure to non-evaporating substances applied by means of spraying processes, the deterministic model SprayExpo was revised, thoroughly tested, and compared to the existing models ConsExpo and BG-Spray in this research work. To this end, SprayExpo was validated with measurement results from real workplaces in the fields of antifouling and stored product protection. An improved droplet impaction module for calculating the overspray during spraying onto a surface was incorporated into the SprayExpo model. Furthermore, it is no longer necessary to directly enter primary droplet distributions. Instead, for common spraying techniques these are stored in a database from which they can be retrieved by specifying the spraying technique and simple process parameters such as the spraying pressure. The sensitivity analysis revealed that besides the active substance release rate, the droplet spectrum is the decisive process parameter for the exposure. In contrast, the vapor pressure of the solvent only plays a secondary role for the exposure concentration of the active ingredient within the relevant range of values. To validate the SprayExpo model, exposure concentrations of the active substances used were determined at workplaces in the area of antifouling treatment and in several scenarios in stored product protection by personal sampling and subsequent chemical analysis. For both room spraying and spraying onto walls, comparisons between the model and experiments revealed that spray applications can generally be reproduced with an uncertainty factor of less than 4. As regards the dermal exposure, the model can only take into account the sedimentation flow of the airborne droplets, but not accidentally occurring splashes. Therefore, the dermal exposure at the workplace is underestimated by SprayExpo in the majority of cases. However, the dermal exposure is represented quite well in the case of room spraying. Based on the measured scenarios, three standard exposure scenarios were defined and documented in corresponding 'fact sheets'. All in all, SprayExpo is an appropriate system for assessing exposure during indoor spraying processes. However, the fact that all models have their advantages and disadvantages should be taken into consideration. Therefore, the models have to be used reasonably and with the required expert knowledge
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