A Risk Assessment Approach for Evaluating the Impact of Toxic Contaminants Released Indoors by Considering Various Emergency Ventilation and Evacuation Strategies

Abstract

The release of toxic airborne contaminants resulting from terrorist attacks on buildings can lead to disastrous consequences. To evaluate and reduce the effects of these emergencies, various methods and models have been developed in the past few years. Such work has provided effective tools for the building management system to do risk assessment of the contaminated areas. Although risk analysis methods to describe the contaminant dispersion scenarios made significant progress, these approaches did not generally consider the releasing scenario occurring in the ventilation system and the effect of human behavior during the developing process of an emergency event. Emergency strategies chosen by the decisionmaker are not always associated with the early-warning system, such as the sensor monitoring network and the source identification system inside the building. This study aims to provide a risk assessment model considering both the variation of contaminant concentration and occupant distribution after the release of toxic agents to obtain the exposure risk for people indoors. The contaminant dispersion is simulated using computational fluid dynamics. The evacuation process for people is modeled using Pathfinder, and the exposure risk for occupants under various emergency strategies is calculated using the efficiency factor of the contaminant source. The results of the exposure risk for 40 basic cases are discussed, and the optimal ventilation mode for these specific cases is recommended. Next, the impact of the variation of human behavior, contaminant detection time needed by sensors, and source identification time needed by inverse modeling on the exposure risk for people indoor is studied. The uncertainty and reproducibility of the numerical simulations are emphatically discussed in the Supporting Information.

A Simulation Analyzing Approach to Estimating the Probability of Airborne Infection Risks in Railway Station Platform Coupling with the Wells-Riley Model and Pathfinder Model

“…Coupling building science model and the Wells-Riley model can be a promising means to simulate a confined environment that accomplishes the goals of improving the accuracy of risk results by further optimising a spatial analysis. In this study, Pathfinder was selected because it can track the routes of each occupant and define his or her response to the incident by considering typical behaviours [ 16 ].…”

The Mechanism of Crowd Stampede Based on Case Statistics through SNA Method

“…Existing research on crowd stampede generally prioritizes analysis of crowd-level behaviour errors in risk events and is insufficient in discussion on organizational-level management factors. Insufficient attention has been paid to the interaction between risk factors, particularly the lack of in-depth research on the causality and mechanism of risk factors [11,12]. This study screens out the risk factors of accidents from multiple perspectives such as pedestrian, equipment, environment and management, analyzes the network correlation mode and effectiveness between different influencing factors, determines the path of risk transmission in the system, and explores the mechanism of accident occurrence, providing practical guiding significance for the reduction of stampede risk.…”