Impact of particulate matter (PM) emissions from ships, locomotives, and freeways in the communities near the ports of Los Angeles (POLA) and Long Beach (POLB) on the air quality in the Los Angeles county

Abstract

In this study, we evaluated the emission rates of ambient fine particulate matter (PM2.5) mass, particle number (PN), and black carbon (BC) from sources at the Ports of Los Angeles (POLA) and Long Beach (POLB), including ships, cargo-handling equipment (CHE), locomotives, and heavy-duty vehicles (HDVs) operating at the ports terminal, as well as from vehicles on the nearby freeways. We also evaluated the impact of these emissions on local air quality (i.e., within the “impact zone” of POLA and POLB), and on the air quality in the Los Angeles County. The impact zone of POLA and POLB was defined as the area confined by the I-105, I-110, and I-710 freeways, and the ports’ ship terminals. At the local scale, emission rates were dominated by the sources at the ports (i.e., ships, locomotives, CHE, and HDVs operating at the ports), with overall PM2.5, PN, and BC emission rates of 97.8 ± 9.8 kg day−1, 91.6 ± 10.6 × 1019 particles day−1, and 60.3 ± 5.3 kg day−1, respectively. Emission rates from sections of the abovementioned nearby freeways were considerably lower, with corresponding values of 8.4 ± 3.8 kg day−1 for PM2.5, 2.4 ± 1.3 × 1019 particles day−1 for PN, and 2.0 ± 1.6 kg day−1 for BC. However, at the scale of Los Angeles County, the emission rates from total freeways across the Los Angeles County were significantly higher than those of the POLA and POLB, with overall values of 506.9 ± 20.3 kg day−1 for PM2.5, 1.9 ± 0.4 × 1021 particles day−1 for PN, and 119.4 ± 10.2 kg day−1 for BC. Our findings illustrate the major impact of emissions from POLA and POLB on the air quality of communities in the vicinity of the port. However, across the Los Angeles County as a whole, freeway emissions become the most important source of PM2.5, PN, and BC emissions, with emission rates 2–5 times higher than those of source categories at POLA and POLB.