A study to monitor and model ultrafine particles (UFP) and black carbon was performed at and in the vicinity of Los Angeles International Airport. The study was designed to capture the highly time-varying nature of ultrafine particle emission from aircraft by using near real time instruments. Three field studies were performed in Los Angeles during 2005-2006. Field studies used near real time instruments to measure the number concentrations of UFP with high temporal resolution. Size distributions of ultrafine particles collected immediately downwind of aircraft take off showed very high number concentrations of UFP, with the highest numbers found at a particle size of approximately 14 nm (dN/dlogDp = 1.4 x 106). The highest spikes in the time profile of UFP number concentrations were clearly correlated with aircraft take off events. Total UFP counts exceeded 107/cm3 during some monitored take offs . Time averaged concentrations of PM2.5 mass and two carbonyl compounds, formaldehyde and acrolein, were elevated at the airport site relative to a background reference site. Other volatile organic compound concentrations were unremarkable. 15 nm particles can be detected 600 m east of LAX, and spikes of particle number were again associated temporally with aircraft activity. Farther downwind, number concentrations of UFP collected in a residential community approximately 2-3 km east of LAX were intermediate in concentration between the airport runway and the background reference site. The curve shape of the UFP size distribution at the community sites was similar to that of the runway site, with peak particle numbers occurring between 10 and 20 nm. While number concentrations of very small particles were high at the community locations studied, the mass-based measures of particulate matter exposure used in this study, black carbon and PM2.5concentration, did not indicate elevated exposures in the community. The results of the project demonstrate that in-use commercial aircraft at LAX emit large quantities of UFP at the lower end of currently measurable particle size ranges. 10-20 nm particles emitted from aircraft are also present at relatively high number concentrations in an adjacent community but an expanded and more in-depth study is needed to determine whether aircraft are indeed the source. In addition, toxicological research on aircraft emitted particulate matter is needed to characterize the potential public health impacts, and a complete chemical characterization of aircraft emitted PM is important to enhance understanding of exposure and public health implications.
For questions regarding this research project, including available data and progress status, contact: Research Division staff at (916) 445-0753
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