Air pollution exposure
disparities by race/ethnicity and socioeconomic
status have been analyzed using data aggregated at various spatial
scales. Our research question is this: To what extent does the spatial
scale of data aggregation impact the estimated exposure disparities?
We compared disparities calculated using data spatially aggregated
at five administrative scales (state, county, census tract, census
block group, census block) in the contiguous United States in 2010.
Specifically, for each of the five spatial scales, we calculated national
and intraurban disparities in exposure to fine particles (PM
2.5
) and nitrogen dioxide (NO
2
) by race/ethnicity and socioeconomic
characteristics using census demographic data and an empirical statistical
air pollution model aggregated at that scale. We found, for both pollutants,
that national disparity estimates based on state and county scale
data often substantially underestimated those estimated using tract
and finer scales; in contrast, national disparity estimates were generally
consistent using tract, block group, and block scale data. Similarly,
intraurban disparity estimates based on tract and finer scale data
were generally well correlated for both pollutants across urban areas,
although in some cases intraurban disparity estimates were substantially
different, with tract scale data more frequently leading to underestimates
of disparities compared to finer scale analyses.