General Plan Update - City of Inglewood

5.6 Air Quality
The most congested roadway segments in the City of Inglewood—those that experience
very high traffic volumes and low levels of service during peak hours—could potentially
create CO “hotspots” where the ambient air quality standards for CO are temporarily
exceeded. Any hotspots would have the potential to adversely affect nearby sensitive uses.
CO concentrations were estimated at various roadway segments throughout the City that
currently contain high traffic volumes. CO concentration estimates were based on
existing Year 2005 traffic volumes. The protocol recommended by the California
Department of Transportation (Caltrans) and published in the Transportation Project-Level
Carbon Monoxide Protocol (1997) were used when estimating CO concentrations. It is also
consistent with procedures identified through the SCAQMD’s CO modeling protocol in
the CEQA Air Quality Handbook. Traffic CO contributions were estimated using the
Caltrans CALINE4 dispersion model.
Existing CO concentrations at the analyzed roadway segments are shown in Table 5.6-3.
Presently, none of the roadway segments analyzed exceed the State one-hour and eighthour
CO standards of 20.0 ppm and 9.0 ppm, respectively. The State one-hour and eighthour
CO standards are more stringent than the National one-hour and eight-hour CO
standards.
In addition to surface streets, existing CO concentrations generated by traffic traveling on
Interstate 405 and Interstate 105 were estimated at residences nearest to the respective
freeway. Traffic volumes were obtained from the California Department of
Transportation. 88 As shown in Table 5.6-3, one-hour and eight-hour CO concentrations
along Interstate 405 are approximately 11.6 and 8.2, respectively. One-hour and eighthour
CO concentrations along Interstate 105 are approximately 10.9 and 7.7, respectively.
CO levels generated by traffic traveling Interstate 405 and Interstate 105 do not exceed
the State one-hour and eight-hour CO standards of 20.0 ppm and 9.0 ppm, respectively,
at the nearest sensitive receptor.
Existing Toxic Air Contaminants
Toxic air contaminants are airborne substances that are capable of causing chronic and
acute adverse effects on human health. They include both organic and inorganic chemical
substances that may be emitted from a variety of common sources, including gasoline
stations, motor vehicles, dry cleaners, industrial operations, painting operations, and
research and teaching facilities. TACs are different than the “criteria pollutants“
previously discussed in that ambient air quality standards have not been established for
them; this is primarily due to the large number of air toxics and the localized nature of the
adverse health impacts caused by TAC emissions. TACs are typically of greatest concern
near facilities that store or use toxic compounds. Mostly, sources such as those described
above are generated from manufacturing and industrial uses.
88 The most recent freeway counts from the California Department of Transportation were for Year 2004.
A three percent growth rate was added to the freeway traffic volumes to obtain Year 2005 traffic volumes.
City of Inglewood General Plan Update Technical Background Report
5.6-11