Los Angeles International Airport Air Quality and Source Apportionment Study

摘要

The study included four core stations and 13 satellite and gradient stations to measure ambient air pollutant concentrations during the study period. Considering unique local weather conditions and aircraft traffic patterns, two six-week sampling seasons: "Winter Season" (January 31 to March 13, 2012) and "Summer Season" (July 18 to August 28,2012) were conducted. The field measurements at four "core sites" included continuous monitors and time-integrated (24-hour) samplers for various air pollutants. Integrated satellite sites and gradient monitoring sites contained a combination of time-integrated samplers and passive samplers. Additionally, a mobile survey was conducted in the beginning of the study to facilitate the selection of the monitoring sites. A supplementary study was also conducted to further investigate the potential sources of UFPs. At the four core sites, the maximum concentrations of criteria air pollutants during the study were all below existing National and California Ambient Air Quality Standards and levels of selected air toxic compounds were comparable or lower than the levels measured at other urban monitoring sites in the South Coast Air Basin. Higher pollutant levels were measured close to sources, such as near airport airfields and busy roadways. The pollutant levels were observed to decrease rapidly downwind in a manner consistent with the pollutant gradient measurements made prior to the ambient monitoring during the mobile survey. The contributions of airport-related emissions can vary by hour of the day, day of the week, and by season. Factors such as airport activity levels, wind direction, wind speed, ambient temperature, and other meteorological parameters, affect the contribution of airport-related emissions to local ambient air quality. From the emissions inventory conducted, the results showed that approximately 23 to 36 percent of the emissions within the Study Area were related to the airport. Aircraft and ground support equipment were the largest airport-related emission sources. The airport-related traffic emissions (both on- and off-airport) were approximately 12 percent of the total traffic-related carbon monoxide (CO), volatile organic compounds (VOC), oxides of nitrogen (NO_x), and sulfur oxides (SO_x) and approximately 36 percent of the particulate matter (PM) with a diameters less than 10 micron and 2.5 micron (PM_(10) and PM_(2.5)). Main sources of NO_x, CO, and black carbon (BC) in the Study Area were motor vehicles in local traffic near the 1-105 and 1-405 freeway. Additionally, 90 percent of the ambient particulate matter was from non-airport related sources and regional background including secondary aerosols. Main sources areas for sulfur dioxide (SO_2) were around the Central Terminal Area and the north and south airfields. From supplemental studies of UFPs, it was determined that larger size UFP was associated with vehicle emissions while smaller size UFP was from jet exhausts and possibly secondary aerosols.