Environmental Engineering Reference
In-Depth Information
Phoenix is located in a shallow river valley where frequent temperature inversions during
the cooler winter months trap and concentrate industrial and transportation-generated
pollutants over the city. Unlike other Southwestern cities, Phoenix lacks consistent
background atmospheric circulation contributing to the buildup of air pollutants.*
Industrial and transportation related emissions are compounded by high particulate lev-
els that derive from the dry conditions and dust produced by construction, gravel pit
operations, agriculture, and unpaved roads on the urban periphery. While concerns over
criteria air pollutants and Phoenix's frequent “brown cloud” looming over the city are
frequently voiced by residents,
†
for environmental justice movements in the city, the great-
est concerns are with the location of industrial polluters in minority neighborhoods.
20
Recent research suggests these concerns are justified.21
21
17.4 Phoenix's Riskscape
While most environmental justice research considers the geographic distribution of a
single hazard such as hazardous waste handlers (treatment, storage, and disposal facilities
or TSDFs), our research investigates the distributions of four types of hazards
‡
in the
Phoenix metropolitan area. These include industrial facilities emitting toxic substances
regulated under the EPA's TRI, manufacturing facilities that produce hazardous wastes
(large-quantity generators or LQGs), TSDFs, and toxic contamination sites listed by the
federal government under provisions of CERCLA and the national priority list (NPL or
Superfund). We document the spatial concentration and compounding of potential risks
produced by the agglomeration of these four common types of point-source hazards in
neighborhoods with racially and economically marginalized residents. Table 17.1 presents
an overview of the number of hazard sites by category included in this study of Phoenix.
To calculate relative hazard burdens of each tract in the metro area, we utilize an approach
that assesses the cumulative hazard burdens in census tracts based on .62 mile (1 km)
radius buffer zones around each hazard site for each of the four types of hazards. These
multiple overlapping hazard zones are summed for each census tract they overlay and the
value standardized by the total area of each tract. The resulting cumulative hazard density
index (CHDI) calculates the accumulation of all hazard buffers that overlap a given census
tract.
§
The index provides an aggregate hazard score for each tract which is then correlated
with demographic data in order to measure levels of environmental inequity in Phoenix.
*
Ellis.
17
See also Grineski et al.
18
†
See, for example, PASS.
19
‡
The annual TRI provides release data on industrial polluters, including information on the volume, chemical
composition, and location of the polluting facilities. Reporting industries must employ at least 10 workers and
it manufactures or CERCLA—the Comprehensive Environmental Response, Compensation, and Liability Act
processes over 25,000 lb of at least one of the currently listed 600 TRI chemicals, or uses more than 10,000 lb of
at least one TRI chemical. See http://www.epa.gov/year2000/toxic.html (accessed August 12, 2011) provides
the legal mandates for the investigation and regulation of a wide range of toxic contamination sites. CERCLIS,
the Information System maintained under the act, lists heavily contaminated sites (toxic waste dumps,
abandoned industrial sites, mines, contaminated federal facilities etc.). See http://rtk.net/cerclissearch.html
(accessed August 12, 2011). Large Quantity Generator designations include facilities that produce or accumu-
late at least 2200 lb of RCRA regulated hazardous waste on a monthly basis. TSDFs comprise a subset of LQGs
that treat, store, or dispose of hazardous wastes. See http://d1.rtknet.org/brs/ (accessed August 12, 2011).
§
For a full discussion on this topic, see Bolin et al.
22
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