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Outdoor air pollution and uncontrolled asthma in the San Joaquin Valley, California
  1. Ying-Ying Meng1,
  2. Rudolph P Rull2,3,
  3. Michelle Wilhelm4,
  4. Christina Lombardi1,
  5. John Balmes5,6,
  6. Beate Ritz4
  1. 1UCLA Center for Health Policy Research, Los Angeles, California, USA
  2. 2Northern California Cancer Center, Berkeley, California, USA
  3. 3Department of Health Research and Policy, Stanford University School of Medicine, Stanford, California, USA
  4. 4Department of Epidemiology and Center for Occupational and Environmental Health, School of Public Health, University of California, Los Angeles, California, USA
  5. 5Department of Medicine, University of California, San Francisco, California, USA
  6. 6Division of Environmental Health Sciences, School of Public Health, University of California, Berkeley, California, USA
  1. Correspondence to Dr Ying-Ying Meng, 10960 Wilshire Blvd, Suite 1550, Los Angeles, CA 90024, USA; yymeng{at}


Background The San Joaquin Valley (SJV) in California ranks among the worst in the USA in terms of air quality, and its residents report some of the highest rates of asthma symptoms and asthma-related emergency department (ED) visits and hospitalisations in California. Using California Health Interview Survey data, the authors examined associations between air pollution and asthma morbidity in this region.

Methods Eligible subjects were SJV residents (2001 California Health Interview Survey) who reported physician-diagnosed asthma (n=1502, 14.6%). The authors considered two outcomes indicative of uncontrolled asthma: (1) daily or weekly asthma symptoms and (2) asthma-related ED visits or hospitalisation in the past year. Based on residential zip code, subjects were assigned annual average concentrations of ozone, PM10 and PM2.5 for the 1-year period prior to the interview date from their closest government air monitoring station within an 8 km (5 miles) radius.

Results Adjusting for age, gender, race/ethnicity, poverty level and insurance status, the authors observed increased odds of experiencing daily or weekly asthma symptoms for ozone, PM10 and PM2.5 (ORozone 1.23, 95% CI 0.94 to 1.60 per 10 ppb; ORPM10 1.29, 95% CI 1.05 to 1.57 per 10 μg/m3; and ORPM2.5 1.82; 95% CI 1.11 to 2.98 per 10 μg/m3). The authors also observed increased odds of asthma-related ED visits or hospitalisations for ozone (OR 1.49, 95% CI 1.05 to 2.11 per 10 ppb) and a 29% increase in odds for PM10 (OR 1.29, 95% CI 0.99 to 1.69 per 10 μg/m3).

Conclusions Overall, these findings suggest that individuals with asthma living in areas of the SJV with high ozone and particulate pollution levels are more likely to have frequent asthma symptoms and asthma-related ED visits and hospitalisations.

  • Air pollution
  • asthma
  • environmental public health tracking
  • ozone
  • particulate matter

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  • Funding This study was supported by the Centers for Disease Control and Prevention as part of the University of California, Berkeley Center of Environmental Public Health Tracking Center.

  • Competing interests None.

  • Ethics approval Ethics approval was provided by the University of California, Los Angeles Institutional Review Board.

  • Provenance and peer review Not commissioned; externally peer reviewed.

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