CalEnviroscreen Version 1.1 - OEHHA - State of California

CalEnviroScreen 1.1
disadvantaged areas (Szasz and Meuser, 1997). Additionally, race and
ethnicity have been correlated with the presence of toxic release
facilities. People of color in studied regions of southern California were
found to have a greater likelihood of living in areas with higher toxic
releases (Morello-Frosch et al., 2002; Sadd et al., 1999).
Method o Data on the location and toxicity-weighted emissions for facilities in
California, or within one kilometer of California, were extracted
from TRI using the TRI.NET program for 2008, 2009, and 2010.
(http://www.epa.gov/tri/tridotnet/index.html)
o Toxicity-weighted on-site emissions to air and water were selected.
(Releases to land and off-site transfers were excluded.)
o Facility locations with a valid latitude and longitude were mapped.
Facility locations with address only were geocoded (ArcMap).
o A 1 kilometer (km) circular buffer (~3.14 km 2 ) was placed around
each facility.
o ZIP codes were scored by summing the toxicity-weighted pounds of
emissions for all facilities within the ZIP code or within one kilometer
of the ZIP code, using an area-apportionment method:
• If the 1 km buffer of a facility was fully located within a ZIP
code, the toxicity-weighted pounds were fully applied to the ZIP
code.
• If the 1 km buffer crossed adjacent ZIP code(s), a portion of the
toxicity-weighted pounds was applied to the ZIP codes based on
the portion of the buffer located in each ZIP code area. For
example, if the measured area of a facility’s buffer was half in
one ZIP code and half in another, 50 percent of the toxicityweighted
pounds was assigned to each ZIP code.
o Facilities that do not fall within the boundaries of census ZIP codes
(or within the 1 km buffer) were added to the toxicity-weighted
pounds of the census ZIP code that corresponds to the facility’s ZIP
code reported in the TRI database.
o For a three-year average, toxicity-weighted emissions by ZIP code
were calculated for the years 2008 to 2010, individually, and then
averaged.
• ZIP codes were assigned a percentile based on their position in
the distribution of ZIP codes with a facility located within it or
within 1 km of the ZIP code. (If facilities are located within a ZIP
code but all had no reported emissions for 2008-2010, the ZIP
code is assigned the lowest percentile value.)
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