  Viral spread has been intermittently threatening human life over time.
Characterizing the viral concentration and modelling the viral transmission
are, therefore, considered major milestones for enhancing viral detection
capabilities. This paper addresses the problem of viral aerosol detection based
on the exhaled breath in a bounded environment, e.g., a bounded room. The paper
models the exhaled breath as a cloud which is emitted through the room
continuously, and analyzes the temporal-spatial virus concentration by
accounting for partial absorption and reflection at each side of the room. The
paper first derives a closed form expression of the temporal-spatial virus
concentration. It then considers the deployment of a receiver composed of an
air sampler and a bio-sensor to detect the viral existence of a specific virus.
We, therefore, assess the detection capabilities of the proposed system via
evaluating the viral miss-detection probability as a function of the sampling
volume and the detection time-instance at the receiver side. Our numerical
simulations verify the validity of the analytical results, and illustrate the
ability of the proposed system to detect viruses in indoor environments. The
results further characterize the impacts of several system parameters on the
miss-detection probability.
