Assessing Dynamic Exposure to Air Pollution - Space-Time Integration in Geography and GIScience - page 292

factors, results of the study do not necessarily mean that people's daily movement
does not affect their exposure to air pollution in general.
Also important in leading to the results is the lack of an adequate geographic
coverage of the mobile and minor pollution sources of particulate matter in the
study area. These sources include vehicular traffic, restaurants, auto body shops,
gas stations, dry cleaners and home heating systems. Generally speaking, the only
way to account for pollution generated by these sources is to rely on local monitors
that collect samples at varying temporal resolutions. Ideally, a dense monitoring
network that represents urban, suburban and rural areas within the study area would
capture the impact of these sources on the quality of surrounding air. This in turn
would allow people's dynamic exposure to be assessment more accurately. There
are, however, only three local monitors in the study area which are all located in the
north of and within 6 km from downtown Columbus. This extreme lack of monitored
data made it difficult to accurately represent particulate matter emissions from the
mobile and minor pollution sources in the study area. Further, location of these
monitors also means that the pollution sampling was only representative of areas
fairly close to the city center. As a result, although emission data from the three
local monitors were incorporated into the pollution estimates in the study, they did
not seem to have effectively captured people's dynamic exposures (in light of the
fact that many trips were made to the urban opportunities located in the northern
suburbs which have no local pollution monitors). Thus to more accurately assessed
people's dynamic exposure to air pollution, many more monitoring sites would be
necessary for this type of analysis in the future.
While the results are less promising than what were expected, this study still
contributes to air pollution assessment methods in important ways. It proposed the
notion of dynamic exposure, and developed and implemented a GIS-based method
for evaluating people's exposure to air pollution that takes into account of the
location of their out-of-home activities and trips. The method will be especially
relevant for future studies on environmental health because high-resolution space-
time data on human movement are becoming increasingly available through the use
of new survey methodologies and advance geospatial technologies (e.g., accurate
route data can now be collected using GPS). To be able to assess people's dynamic
exposures more accurately, however, not only a dense monitoring network is needed
to capture particulate concentrations, local monitors should also provide pollution
data at higher temporal resolution (e.g., for every hour or 30-min intervals).
References
Bartonova, A., Clench-Aas, J., Gram, F., Gronskei, K. E., Guerreiro, C., & Larssen, S. (1999). Air
pollution exposure monitoring and estimation. Part V. Traffic exposure in adults. Journal of
Environmental Monitoring, 1 , 337-340.
Bell, M. L. (2006). The use of ambient air quality modeling to estimate individual and population
exposure for human health research: A case study of ozone in the Northern Georgia Region of
the United States. Environmental International, 32 , 586-593.