Identification of Effects of Regulatory Actions on Air Quality in Goods Movement Corridors in California

Abstract

Few studies have assessed the impact of regulatory actions on air quality improvement through a comprehensive monitoring effort. In this study, we designed saturation sampling of nitrogen oxides (NOX) for the counties of Los Angeles and Alameda (San Francisco Bay) before (2003-2007) and after (2008-2013) implementation of goods movement actions in California. We further separated the research regions into three location categories, including goods movement corridors (GMCs), nongoods movement corridors (NGMCs), and control areas (CTRLs). Linear mixed models were developed to identify whether reductions in NOX were greater in GMCs than in other areas, after controlling for potential confounding, including weather conditions (e.g., wind speed and temperature) and season of sampling. We also considered factors that might confound the relationship, including traffic and cargo volumes that may have changed due to economic downturn impacts. Compared to the pre-policy period, we found reductions of average pollutant concentrations for nitrogen dioxide (NO2) and NOX in GMCs of 6.4 and 21.7 ppb. The reductions were smaller in NGMCs (5.9 and 16.3 ppb, respectively) and in CTRLs (4.6 and 12.1 ppb, respectively). After controlling for potential confounding from weather conditions, season of sampling, and the economic downturn in 2008, the linear mixed models demonstrated that reductions in NO2 and NOX were significantly greater in GMCs compared to reductions observed in CTRLs; there were no statistically significant differences between NGMCs and CTRLs. These results indicate that policies regulating goods movement are achieving the desired outcome of improving air quality for the state, particularly in goods movement corridors where most disadvantaged communities live.

Examining air pollution exposure dynamics in disadvantaged communities through high-resolution mapping

“…It is confirmed not only by this research but also by other studies (57-59) that the unequal distribution of air pollution exacerbates health disparities, perpetuating environmental injustice. The disadvantaged communities, being in close proximity to air pollution emissions sources, have likely experienced notable improvements in air quality, thus benefiting most from the regulatory efforts aimed at reducing air pollution (60). These improvements underscore the progress made toward environmental justice due to these regulatory actions.…”

Modeling the Health Benefits of Superblocks across the City of Los Angeles

“…The City of LA is the second-largest city in the United States and well known for its sprawling metropolitan area, traffic congestion and traffic related air pollution (TRAP) [10]. In addition, the presence of two major seaports and the associated goods movement infrastructure creates additional emissions from diesel vehicles [11][12][13]. To counter the adverse health impacts of air pollution, the City of LA has explored the use of transit malls, people-first streets and superblocks to reduce gasoline-powered automobiles and diesel freight vehicles passing through neighborhoods, TRAP, noise and the urban heat island effect [14].…”