Air quality in a given region is determined by the concentration of various pollutants in the atmosphere as well as the size and topography of the basin, and its meteorological conditions. The South Coast Air Basin has low mixing heights and light winds - this combination is conducive to the accumulation of air pollutants.

Air quality is measured by comparing contaminant levels in ambient air samples to national and state standards. These standards are set by the United States Environmental Protection Agency (EPA) and California Air Resources Board (CARB) at levels to protect public health and welfare, with an adequate margin of safety to protect the most sensitive individuals in the population. Air quality standards specify the upper limits of concentrations and duration in the ambient air, consistent with the management goal of preventing specific harmful effects.

The EPA establishes the National Ambient Air Quality Standards (NAAQS); maximum pollutant concentrations generally may not exceed these annual standards. CARB establishes the state California Ambient Air Quality Standards (CAAQS); maximum pollutant concentrations may not equal or exceed the CAAQS. Pollutants that have established national or state ambient air quality standards are referred to as criteria pollutants. The criteria pollutants considered in this air quality section include ozone (O3), carbon monoxide (CO), nitrogen dioxide (NO2), sulfur dioxide (SO2), and particulate matter less than 10 microns in diameter (PM10). Although there are no ambient standards for reactive organic gases (ROGs) or nitrogen oxides (NOx), they are considered important precursors to O3 and are included in this evaluation.

Baseline Air Quality
The SCAB has been in non attainment for the state and federal O3, and PM10 for some time. The SCAB has recently reached attainment for CO. The basin is classified as attainment for the state and federal NO2 and SO2 standards.

Table 1-2 summarizes federal and state attainment and non attainment status for considered pollutants.

Table 1-2
Attainment Status of Ambient Air Quality Standards

Maximum pollutant concentrations over the past 3 years at this station are presented in Table 1-3. In addition, Table 1-3 presents a comparison of monitoring station results to the federal and state ambient air quality standards and shows that existing ambient air quality at this station exceeded state ambient air quality standards within the past three years for O3, PM10, and PM2.5.

Table 1-3
Ambient Air Quality Monitoring Data from North Long Beach Monitoring Station

Table 1-3 (2000-03)

Table 1-3 (2004-06)

The monitoring data provided above is from a location in North Long Beach. Recently, POLA has initiated ambient monitoring in the harbor area. The monitoring results can be found in the following report online: Caap Reports. Figure 1-1 summarizes preliminary results from these monitoring efforts at the Wilmington station. Additional information is available at the POLA website.

Figure 1-1
Ambient Air Quality Monitoring Data from

Toxic Air Contaminants
Toxic Air Contaminants (TACs) have no established ambient standards, but are known or suspected to cause acute and/or chronic (carcinogenic or non-carcinogenic) health effects. The SCAB TAC sources include fossil fuel combustion, industrial processes, paint and solvent operations, gasoline stations, etc.

To date, the most comprehensive study on air toxics in the SCAB is the Multiple Air Toxics Exposure Study (MATES II), conducted by the SCAQMD. The monitoring program measured more than 30 air pollutants, including both gaseous emissions and particulates. The monitoring study was accompanied by a computer modeling study in which SCAQMD estimated the risk of cancer throughout the region, based on emissions and weather data.

MATES II found that the average cancer risk in the region from carcinogenic air pollutants ranges from about 1,100 in a million to 1,750 in a million, with an average regional risk of about 1,400 in a million. The higher risk levels were found in the urban core areas in south central Los Angeles County, in Wilmington adjacent to the Port, and near freeways.

The study showed that airborne Diesel Particulate Matter (DPM) contributes about 70 percent of the cancer risk. Mobile sources account for about 90 percent of this DPM cancer risk, and industries and other stationary sources account for the remaining 10 percent. Due to the prevalence of diesel-powered sources associated with operations at the San Pedro Bay Ports, MATES II identified that this area has some of the highest ambient cancer risks due to air emissions of any area within the SCAB.