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STATE OF CALIFORNIA 

SUPPLEMENTAL INFORMATION FOR 

RECOMMENDED LEAD NONATTAINMENT AREA 

SOUTH COAST AIR BASIN PORTION OF LOS ANGELES COUNTY

EXCLUDING THE CHANNEL ISLANDS 

EIGHT FACTOR ANALYSIS 

INTRODUCTION 

The Air Resources Board previously submitted justification for designating the 

South Coast portion of Los Angeles County as nonattainment for the 2008 lead 

national ambient air quality standard. This document provides the justification for 

also excluding San Clemente and Santa Catalina islands from the nonattainment 

area, using the eight factors U.S. EPA recommends for evaluating lead area 

designations. 

ANALYSIS 

 Jurisdictional Boundaries

As shown in Figure 1, the southern two-thirds of Los Angeles County, including 

San Clemente and Santa Catalina islands, is located in the South Coast Air 

Basin and falls under the jurisdiction of the South Coast Air Quality Management 

District (South Coast AQMD or District). Pollutant concentrations are 

FIGURE 1 

LOS ANGELES COUNTY 
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substantially higher in the mainland South Coast portion of the County because 

several significant lead-related stationary sources are located there, in the City of 

Commerce, the City of Industry, Santa Fe Springs, and Vernon. As a result, the 

South Coast AQMD has implemented rigorous, source-specific, emissions 

control requirements. Although the entire area is under the jurisdiction of a single 

control agency, the disparity among emissions sources justifies limiting the lead 

nonattainment area to the mainland South Coast portion of Los Angeles County. 

 Air Quality Data

Lead concentrations are monitored at a number of sites in the mainland South 

Coast portion of Los Angeles County. Some of these sites are located near 

lead-related stationary sources, while others are neighborhood scale sites. 

Based on data for the sites located near lead-related sources, the design value 

for the South Coast portion of Los Angeles County is 2.49 micrograms per cubic 

meter (μg/m3), which exceeds the 2008 federal lead standard. This value was 

measured near the Exide Technologies facility in Vernon. Values for the 

District’s other source-oriented sites surrounding the Exide facility are lower, with 

maximum 3-month averages ranging from 0.03 μg/m3 to 0.55 μg/m3. 

Concentrations at sites surrounding the other lead-related facilities also show a 

decrease in concentration with distance from the source, confirming the rapid 

drop in lead concentrations with distance. This relationship provides additional 

support for limiting the size of the nonattainment area. 

In addition to the source-related lead samplers, the District maintains a network 

of neighborhood scale sites. Lead concentrations measured at all of these sites 

are well below the federal standard, ranging from less than 0.01 μg/m3

 to 

0.03 μg/m3

. These values are based on data for 2005 through 2007, the most 

recent complete three-year period for which data are available. Although there 

are no monitoring data available for San Clemente or Santa Catalina island, we 

expect concentrations there are even lower because of the differences in 

emissions and population, as well as the distance from the mainland County area 

and the rapid drop in lead concentration with distance from a source. 

Emissions Data and Level of Emissions Control

There are significant differences between lead emissions in the mainland and 

offshore South Coast portions of Los Angeles County. The mainland portion of 

the County contains one lead-related stationary source (Exide Technologies) and 

one general aviation airport (Van Nuys Airport) that meet the 1 ton per year 

current threshold of concern for lead. Several other facilities meet the 0.5 ton per 

year threshold being considered by U.S. EPA. The closest of these facilities is 

more than 25 miles from either island. In contrast to the mainland sources, no 

stationary source or general aviation airport that comes close to meeting the 

lower threshold is found on either San Clemente Island or Santa Catalina Island. 
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Given the rapid drop in lead concentration with distance from a source, the South 

Coast mainland facilities do not have any measurable impact on island 

concentrations. 

 

In September 1992, the South Coast District adopted Rule 1420, which is 

specifically aimed at reducing lead emissions from non-vehicular sources. 

Rule 1420 (Emissions Standard for Lead) applies to all facilities that use or 

process materials containing lead, including primary or secondary lead smelters, 

foundries, lead-acid battery manufacturers or recyclers, as well as facilities that 

produce lead-oxide, brass, and bronze. The South Coast District is planning to 

update Rule 1420 to be consistent with the revised federal lead standard. 

Therefore, the Rule will continue to be effective in dealing with high, 

facility-related lead concentrations, and it forms the basis of the District’s lead 

attainment strategy. 

Population Density, Degree of Urbanization, and Expected Growth 

Similar to air quality and emissions, there are vast differences between the 

population and degree of urbanization in the mainland and offshore portions of 

South Coast Los Angeles County. Based on estimates for 2010, the highly 

urbanized South Coast mainland portion of the County has a population of more 

than 10 million. The population of Santa Catalina Island is less than 5,000, while 

San Clemente Island, owned and operated by the United States Navy, is virtually 

uninhabited. This means that more than 99 percent of the population lives in the 

South Coast mainland portion of the County. In terms of size, the South Coast 

mainland portion of Los Angeles County is close to 20 times larger than both 

islands combined. However, the population density is 3,992 people per square 

mile, compared with about 50 people per square mile on Santa Catalina. Given 

the limited size of Santa Catalina Island and the military function of 

San Clemente Island, this discrepancy in population between the mainland and 

island portions of South Coast Los Angeles County is not expected to change. 

Geography and Meteorology

Santa Catalina and San Clemente islands are isolated areas surrounded by 

water. In contrast, the mainland portion of South Coast Los Angeles County is 

part of one of the nation’s largest metropolitan areas. Although an 

onshore/offshore air flow regime impacts both areas, the distance between the 

mainland South Coast portion of the County and the islands offshore precludes 

any significant contribution to lead concentrations from the mainland to the 

islands. 
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SUMMARY AND RECOMMENDATION 

The mainland South Coast portion of Los Angeles County is distinctly different 

from the island portions of the County. The highly urbanized mainland South 

Coast portion is primarily a coastal area with a high population density and a 

concentration of several lead-related processing facilities that have the potential 

to violate the federal lead standard. In contrast, the island portions of the County 

are sparsely populated areas that lack any notable lead emissions sources. 

Because of these differences, the lead air quality problem in the South Coast 

mainland portion of the County is much more significant. Even so, lead 

concentrations exceeding the federal standard are found only near lead-related 

facilities. Lead measurements show these concentrations decrease rapidly with 

distance from the source, and the transport of lead particles or pollutants from 

the South Coast mainland portion of the County to the islands is not expected to 

occur. Although there are no physical barriers between the mainland facilities 

and the offshore portions of the County, there is a significant distance (more than 

25 miles). The heavy weight of lead particles and the quick decrease in 

concentration with distance from the source make any measurable offshore 

transport impact extremely unlikely. 

In terms of air quality regulation, the South Coast portion of Los Angeles County, 

including both the mainland and island areas, falls under the jurisdiction of the 

South Coast AQMD. The District’s primary strategy for dealing with the high lead 

concentrations in the South Coast portion of the County is their Rule 1420, which 

has been effective in reducing source-specific emissions and resulting high 

concentrations. This strategy will continue to address violations of the federal 

lead standard. 

Based on the previous analyses, the Air Resources Board recommends that 

U.S. EPA limit the extent of the federal lead nonattainment area to the mainland 

portion of Los Angeles County located in the South Coast Air Basin.