  Crowd models can be used for the simulation of people movement in the built
environment. Crowd model outputs have been used for evaluating safety and
comfort of pedestrians, inform crowd management and perform forensic
investigations. Microscopic crowd models allow the representation of each
person and the obtainment of information concerning their location over time
and interactions with the physical space/other people. Pandemics such as
COVID-19 have posed several questions on safe building usage, given the risk of
disease transmission among building occupants. Here we show how crowd modelling
can be used to assess occupant exposure in confined spaces. The policies
adopted concerning building usage and social distancing during a pandemic can
vary greatly, and they are mostly based on the macroscopic analysis of the
spread of disease rather than a safety assessment performed at a building
level. The proposed model allows the investigation of occupant exposure in
buildings based on the analysis of microscopic people movement. Risk assessment
is performed by retrofitting crowd models with a universal model for exposure
assessment which can account for different types of disease transmissions. This
work allows policy makers to perform informed decisions concerning building
usage during a pandemic.
