TitleReductions in NO and emergency room visits associated with California's goods movement policies: A quasi-experimental study.
Publication TypeJournal Article
Year of Publication2022
AuthorsMeng, Y-Y, Yue, D, Molitor, J, Chen, X, Su, JG, Jerrett, M
JournalEnviron Res
Date Published10/2022
KeywordsAir Pollutants, Air Pollution, Asthma, California, Emergency Service, Hospital, Humans, Nitrogen Dioxide, Policy, Pulmonary Disease, Chronic Obstructive, Retrospective Studies


  • This is the first study to assess the specific long-term and large-scale regulatory actions on air quality and health.
  • The California Goods Movement interventions was associated with substantial reductions in NO2 exposures.
  • The intervention also led to reductions in emergency room visits among Medicaid beneficiaries with respiratory diseases.
  • This paper contributed to scientific methods for assessing the health effects of regulatory actions.


INTRODUCTION: This study examines whether the "Emission Reduction Plan for Ports and Goods Movement" in California reduced air pollution exposures and emergency room visits among California Medicaid enrollees with asthma and/or chronic obstructive pulmonary disease.

METHOD: We created a retrospective cohort of 5608 Medicaid enrollees from ten counties in California with data from 2004 to 2010. We grouped the patients into two groups: those living within 500 m of goods movement corridors (ports and truck-permitted freeways), and control areas (away from the busy truck or car permitted highways). We created annual air pollution surfaces for nitrogen dioxide and assigned them to enrollees' home addresses. We used a quasi-experimental design with a difference-in-differences method to examine changes before and after the policy for cohort beneficiaries in the two groups.

RESULTS: The reductions in nitrogen dioxide exposures and emergency room visits were greater for enrollees in goods movement corridors than those in control areas in post-policy years. We found that the goods movement actions were associated with 14.8% (95% CI, -24.0% to -4.4%; P = 0.006) and 11.8% (95% CI, -21.2% to -1.2%; P = 0.030) greater reduction in emergency room visits for the beneficiaries with asthma and chronic obstructive pulmonary disease, respectively, in the third year after California's emission reduction plan.

CONCLUSION: These findings indicate remarkable health benefits via reduced emergency room visits from the significantly improved air quality due to public policy interventions for disadvantaged and susceptible populations.

Alternate JournalEnviron Res
PubMed ID35660569