Case Study: Air Toxic Releases in New Jersey
(from Mennis, J. and Jordan, L., 2005.
of environmental equity: exploring spatial nonstationarity in
multivariate models of air toxic releases. Annals of the
Association of American Geographers, 95(2): 249-268)
Geographic information systems (GIS) and multivariate regression are
used to analyze socioeconomic inequity in the spatial distribution
of New Jersey air toxic release facilities listed in the
Environmental Protection Agency's (EPA) Toxic Release Inventory
(TRI). The map below shows New Jersey and the locations of TRI
facilities with air releases.
Data and Methods
TRI facility data for 2000 were acquired from the EPA.
Socioeconomic data (population density, percent black, percent
Hispanic, percent living below the poverty line, and percent
employed in manufacturing) were acquired from the U.S. Bureau of the
Census for the year 2000 at the tract level. Land cover data
were acquired from the U.S. Geological Survey's National Land Cover
Data (NLCD) program. Land cover data were used to calculate
the percentage of each tract classified as
industrial/commercial/transportation. A TRI point density
surface was calculated using a bandwidth of 5 km. The mean
point density was then summarized for each tract. Maps of
these variables are given below.
Kendall's tau-b correlation and multivariate regression were used to
assess the relationship of the socioeconomic and land cover
variables with TRI density.
The table below reports the correlation of TRI density with the