Risk Assessment Using EUSES; Refinement Options to Estimate Atmospheric Transportation by its Operational Priority Substances Model (OPS)

The Operational Priority Substances (OPS) model is part of the European Union System for the Evaluation of Substances (EUSES) and is used to estimate air concentrations and atmospheric depositions for risk assessment of chemicals. Traditionally, EUSES assesses environmental exposure using a standardized scenario based on explicit assumptions and default parameter settings. Under the new European Union REACH legislation—which stands for Registration, Evaluation, Authorisation, and restriction of Chemicals—industry is responsible for the risk assessment of chemicals. The current work investigates the potential impact and importance of source parameter refinement on the emission distribution and environmental fate of chemicals as modelled by OPS. In total, 60 scenarios with different combinations of (non) default values for emission heat content, emission source height, and emission source radius, were run for a typical particle-bound substance. Increasing heat content and emission source height reduced the modelled air concentrations and depositions and caused maximum air concentrations to occur further away from the emission source. Results show that estimated air concentrations and total depositions used for risk assessment can become more realistic by using more site-specific emission source parameters. This article proposes risk assessment refinement options and provides recommendations on future updates of EUSES.