Center for Research in Energy Systems Transformation (CREST)

Ventilation duct serves as a potential target for bioterrorist attack. Understanding the dynamics ofaerosolized harmful agents in the ventilation ducts provides the fundamentals for effective control andmanagement, e.g., risk assessment. In this work, new models for predicting the concentration dynam-ics in the ventilation duct after a particle resuspension (representing the case that harmful agents aredosed when the ventilation is off and subsequently being turned on) or puff injection (representing thecase that harmful agents are dosed when the ventilation is running) event were derived based on themass balance model. The models were validated by a series of wind tunnel experiments. Indoor airborneparticle concentration models were derived by incorporating the proposed ventilation duct models forresuspension and injection cases. The effects of resuspension and injection in the duct on indoor airborneparticle concentration were examined by two hypothetical cases of Bacillus anthracis dosage using thederived models. For the same amount of BW agent dosage in the ventilation duct, the resuspension typerelease prolongs the exposure of harmful agents whereas the injection type release produces a higherpeak concentration.