Air dispersion modeling using the CALPUFF model for a chemical manufacturing facility

Community Exposure Air Modeling

Following mass toxic tort litigation, a chemical manufacturing facility along the Ohio River in northwest West Virginia asked our team to compile emissions information from 1976 to 2012. We also performed air dispersion modeling using the CALPUFF model: a multi-layer, multi-species, non-steady-state puff dispersion model that simulates the effects of time-and-space-varying conditions on pollution transport, transformation, and removal. The purpose of the air dispersion modeling was to provide input into an exposure assessment of the neighboring residents.

Our scientists reviewed thousands of pages of engineering and air emission documents for the facility in order to estimate historical emissions of 44 different chemicals that were known to have been released from the facility. The CALPUFF model was selected because of the potential for valley effects for the facility that was located along a flat in the midst of complex terrain. As a screening level evaluation, the estimated air concentrations were compared to the U.S. Environmental Protection Agency risk-based screening levels (RSLs) for ambient air, and only four chemicals were identified that had estimated air concentrations above the RSLs for any of the receptor locations.

This successful analysis helped the community focus future exposure assessment activities on the chemicals of interest.