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

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• 作者：Jason G. Su ; Ying-Ying Meng ; Melissa Pickett ; Edmund Seto ; Beate Ritz ; Michael Jerrett
• 刊名：Environmental Science & Technology
• 出版年：2016
• 出版时间：August 16, 2016
• 年：2016
• 卷：50
• 期：16
• 页码：8687-8696
• 全文大小：443K
• 年卷期：0
• ISSN：1520-5851

文摘

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 (NO_X) 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 NO_X 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 NO_X 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 NO_X 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.