Analysis of a series of urban-scale chlorine dispersion experiments and implications on indoor health consequences.

In the United States, industrial compounds are routinely transported by rail in pressurized vessels, often near urban areas. A rupture of a vessel, for example due to a derailment, can result in the rapid release of a liquid-aerosol-gas mixture. The health consequences of such a release, especially close to population centers, are not well understood. To address this question, a series of controlled experimental releases of pressurized chlorine (Cl 2) was conducted at the Dugway Proving Ground (Dugway, Utah). Each trial consisted of the sudden breach of a tank containing at least 4,500 kg (kg) of pressurized liquid Cl 2. In this paper, we report on measured Cl 2 concentrations in three test structures downwind of the release. Based on these data, we estimate the indoor-outdoor exchange, transport through a multi-room structure, and the first-order loss rate due to reaction or sorption. This loss rate is particularly important for consequence assessment. For example, in a mobile office with a ventilation rate of about three air changes per hour, the reaction loss rate was approximately 2.5 h−1. This accounts for a nearly 20 percent reduction in toxic load to indoor occupants. Finally, the paper discusses the modeling and analysis of a typical urban hazard assessment. • In 2015 and 2016, a series of controlled release experiments of pressurized chlorine (Cl 2) was conducted. • An experiment consisted of the sudden breaching of a tank containing greater than 4,500 kg (kg) of pressurized liquid Cl 2. • The measurement of the Cl 2 plume's transport through an array of downwind structures. • This paper reports the results of an experiment that is unlikely to be conducted often. • The reaction between the gas and indoor surfaces is important for hazard and consequence assessment. • The current study found that total Cl 2 gas loss was faster than the trailer's air change rate. [ABSTRACT FROM AUTHOR]