Products which are applied by spraying (e.g. pesticides, paints and varnishes) are often associated with high inhalation burden. On the other hand, mechanistic model approaches are available to predict the inhalable exposure from spraying activities. However, these model approach have some limitations.

This report presents an overall model for estimating inhalation exposure caused by spray applications. Three already existing model approaches - developed in earlier BAuA projects - are combined into a 2-level tiered approach. A simple generic 2-box model, as well as SprayExpo and SprayEva, have been reanalysed on plausibility and suitability and if necessary refined. The description of these models including an analysis of the input parameters, and their scope and limitations, resulted in a concept for the overall model. This is followed by the programming of all models in R, and a testing phase using available workplace data, and exemplary situations.

The generic 2-box model does not take into account overspray formation and droplet maturation and settling. This results in the most conservative model estimates and is thus appropriate for a screening approach. The values can be refined if information on release fraction is available based on experiments. As an alternative, with only a few additional information (size class, vapour pressure class) the values can be refined and lowered using correction factors. This refined generic 2-box model still produces more conservative, but partly also similar exposure estimates compared to the higher tier tools. Considering all workplace data, SprayEva usually results close to measured values. Using the higher tier models, the estimates could be made more accurate, but significantly more input information are required.

Overall, the results of the evaluation phase verify the applicability of the tiered approach and the concept of the overall tool.