1991). A second approach utilizes the concept of entropy, where
monitors are located to maximize the entropy in the data collected
by the monitors (Ainslie et al., 2009; Caselton and Zidek, 1984).
Another approach is to define and minimize or maximize an
objective function. An example includes maximizing the number of
monitored violations (Modak and Lohani, 1985). Adams and
Kanaroglou (2015) leveraged historical monitoring data to estimate
the error for mobile monitoring networks that collect
incomplete time-series data. All of these approaches rely on potential
realizations of the air pollution field, which may be obtained
with a temporary monitoring network or from historical data. The
criticality index we propose in this paper is based on the same
principles and utilizes historical data from a monitoring network
for its calculation.