Assessment of an irritant gas plume model for epidemiologic study

Abstract

Previously, we reported the development of a Hazard Prediction and Assessment Capability plume dispersion model of the 2005 Graniteville, South Carolina, USA accidental release of chlorine. Here, we assess this model by spatial and statistical comparison with post-incident observed environmental indicators of exposure and other types of observations. Spatial agreement was found when the model was compared to phytotoxic bleaching and corrosion events observed in 2 km radius around the release site. When spatially compared to locations of injured or killed animals, model predictions of the plume footprint were in relatively good agreement. Model-predicted human casualties differed from observed casualty counts primarily due to the shielding effect of buildings. A statistical comparison of observed dog health outcome-derived exposure vs. model predicted exposure showed relatively good agreement, particularly when a subcohort of indoor dogs was excluded. Evaluation and assessment of the building infiltration effect would further improve the model prior to application in epidemiologic study.

Keywords:

• Epidemiology
• atmospheric
• risk

Acknowledgments

The authors acknowledge the contributions of several colleagues and organizations who have assisted with this work. We acknowledge David Reed, Anja Schultze, Andrew Lawson, Mary Anne Duncan, and Lisa Detter- Hoskin for their instrumental and foundational work as part of this study. Further, we thank the Defense Threat Reduction Agency (DTRA) for access to the HPAC modeling system and the South Carolina Department of Health and Environmental Control (SC DHEC) for the vegetation and human impact data. We also graciously acknowledge the valiant efforts of local emergency responders and public health personnel who helped respond and minimize the adverse health impacts of this disaster on the Graniteville community.