The authors address two research questions: (1) Are populations with lower
socioeconomic status, compared with people of higher socioeconomic status,
more likely to be exposed to higher levels of particulate air pollution in
Hamilton, Ontario, Canada? (2) How sensitive is the association between lev
els of particulate air pollution and socioeconomic status to specification
of exposure estimates or statistical models? Total suspended particulate (T
SP) data from the twenty-three monitoring stations in Hamilton (1985-94) we
re interpolated with a universal kriging procedure to develop an estimate o
f likely pollution values across the city based on annual geometric means a
nd extreme events. Comparing the highest with the lowest exposure zones, th
e interpolated surfaces showed more than a twofold increase in TSP concentr
ations and more than a twentyfold difference in the probability of exposure
to extreme events. Exposure estimates were related to socioeconomic and de
mographic data from census tract areas by using ordinary least squares and
simultaneous autoregressive (SAR) models. Control for spatial autocorrelati
on in the SAR models allowed for tests of how robust specific socioeconomic
variables were for predicting pollution exposure. Dwelling values were sig
nificantly and negatively associated with pollution exposure, a result robu
st to the method of statistical analysis. Low income and unemployment were
also significant predictors of exposure, although results varied depending
on the method of analysis. Relatively minor changes in the statistical mode
ls altered the significant variables. This result emphasizes the value of g
eographical information systems (GIS) and spatial statistical techniques in
modelling exposure. The result also shows the importance of taking spatial
autocorrelation into account in future justice-health studies.