• Project number: F 2492
• Institution: Federal Institute for Occupational Safety and Health (BAuA)
• Status: Completed Project

Description:

According to European regulations on chemical safety, the health risks of employees working with chemical substances and products must be evaluated. An important part of this assessment is the reliable estimation of exposure at the workplace. Often workers are exposed to these substances via the respiratory tract. High inhalation exposures occur, for example, when paints, disinfectants or other chemicals are sprayed.

This project therefore aims to develop an overall model for estimating inhalation exposure during spraying tasks at the workplace. Three existing model approaches were combined into a two-tier overall model: a simple, generic 2-box model, SprayExpo and SprayEva. The development of the individual models and the corresponding programme code had already taken place in earlier BAuA projects. They were analysed for plausibility and suitability and were revised where necessary. Subsequently, the concept for the overall model was developed, taking into account the scopes and limitations of the individual models. In order to be able to publish the overall model as software, the entire model code was implemented in R, a statistical programming language. It was then tested and partially evaluated using available workplace data and example exposure situations.

The comparison of the modelling with measurement data collected at real workplaces showed, that the generic 2-box model delivered the most conservative model estimates and is therefore appropriate for a screening approach. Conservative estimates take safety margins into account when estimating exposure levels and are beneficial, in cases where details about the exposure situation are unknown. In such cases, the actual exposure level is often overestimated. The quality of the predictive values of the generic 2-box model could be improved by introducing correction factors based on two relevant parameters: the droplet size and the solvents vapour pressure. Further refinement is attainable by employing experimentally determined sprayer-specific release fractions while spraying the product into the air. Using SprayExpo and SprayEva provides even more precise estimates, however significantly more input data is required. Comparing all workplace data, the values estimated with SprayEva are usually the closest to the measured values. Overall, the results of the evaluation confirm the applicability of the tiered approach and the concept of the combined model.