Background: The San Joaquin Valley (SJV) in California ranks among the worst in the United States in terms of air quality, and its residents report some of the highest rates of asthma symptoms and asthma-related emergency department (ED) visits or hospitalizations in California. Using California Health Interview Survey (CHIS) data, we examined associations between asthma morbidity and air pollution in this region.
Methods: Eligible subjects were SJV residents (CHIS 2001) who reported physician-diagnosed asthma (n=1,502, 14.6%). We considered two outcomes indicative of uncontrolled asthma: (1) daily or weekly asthma symptoms, and (2) asthma-related ED visits or hospitalization in the past year. Based on residential zip code, subjects were assigned annual average concentrations of ozone, PM10 and PM2.5 for the one-year period prior to the interview date from their closest government air monitoring station within a 5-mile radius.
Results: Adjusting for age, gender, race/ethnicity, poverty level, and insurance status, we observed increased odds of experiencing daily or weekly asthma symptoms for ozone, PM10 and PM2.5 (ORozone: 1.23, 95% CI: 0.94, 1.60 per 10 ppb; ORPM10: 1.29, 95% CI: 1.05, 1.57 per 10 μg/m3; and ORPM2.5: 1.82; 95% CI: 1.11, 2.98 per 10 μg/m3) We also observed a 49% increase in asthma-related ED visits or hospitalizations for ozone (OR: 1.49, 95% CI: 1.05, 2.11 per 10 ppb) and a 29% increase in odds for PM10 (OR: 1.29, 95% CI: 0.99, 1.69 per 10 μg/m3).
Conclusions: Overall, these findings suggest that asthmatic individuals 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 hospitalizations.