Association of short-term exposure to ground-level ozone and respiratory outpatient clinic visits in a rural location - Sublette County, Wyoming, 2008-2011.

OBJECTIVE Short-term exposure to ground-level ozone has been linked to adverse respiratory and other health effects; previous studies typically have focused on summer ground-level ozone in urban areas. During 2008-2011, Sublette County, Wyoming (population: ~10,000 persons), experienced periods of elevated ground-level ozone concentrations during the winter. This study sought to evaluate the association of daily ground-level ozone concentrations and health clinic visits for respiratory disease in this rural county. METHODS Clinic visits for respiratory disease were ascertained from electronic billing records of the two clinics in Sublette County for January 1, 2008-December 31, 2011. A time-stratified case-crossover design, adjusted for temperature and humidity, was used to investigate associations between ground-level ozone concentrations measured at one station and clinic visits for a respiratory health concern by using an unconstrained distributed lag of 0-3 days and single-day lags of 0 day, 1 day, 2 days, and 3 days. RESULTS The data set included 12,742 case-days and 43,285 selected control-days. The mean ground-level ozone observed was 47 ± 8 ppb. The unconstrained distributed lag of 0-3 days was consistent with a null association (adjusted odds ratio [aOR]: 1.001; 95% confidence interval [CI]: 0.990-1.012); results for lags 0, 2, and 3 days were consistent with the null. However, the results for lag 1 were indicative of a positive association; for every 10-ppb increase in the 8-h maximum average ground-level ozone, a 3.0% increase in respiratory clinic visits the following day was observed (aOR: 1.031; 95% CI: 0.994-1.069). Season modified the adverse respiratory effects: ground-level ozone was significantly associated with respiratory clinic visits during the winter months. The patterns of results from all sensitivity analyzes were consistent with the a priori model. CONCLUSIONS The results demonstrate an association of increasing ground-level ozone with an increase in clinic visits for adverse respiratory-related effects in the following day (lag day 1) in Sublette County; the magnitude was strongest during the winter months; this association during the winter months in a rural location warrants further investigation.

[1]  H. Frumkin,et al.  Ambient Air Pollution and Respiratory Emergency Department Visits , 2005, Epidemiology.

[2]  A. Rimm,et al.  Air pollution and emergency department visits for asthma among Ohio Medicaid recipients, 1991-1996. , 2003, Environmental research.

[3]  Allen B. White,et al.  Rapid photochemical production of ozone at high concentrations in a rural site during winter , 2009 .

[4]  Antonella Zanobetti,et al.  The effect of ozone and PM10 on hospital admissions for pneumonia and chronic obstructive pulmonary disease: a national multicity study. , 2006, American journal of epidemiology.

[5]  Relationships between Visits to Emergency Departments for Asthma and Ozone Exposure in Greater Seattle. , 2009, ATS 2009.

[6]  M. Bell,et al.  Meta-analysis of the association between short-term exposure to ambient ozone and respiratory hospital admissions , 2011, Environmental research letters : ERL [Web site].

[7]  M. Amann,et al.  Estimating long-term population exposure to ozone in urban areas of Europe. , 2001, Environmental pollution.

[8]  Modifying Effect of Age on the Association between Ambient Ozone and Nighttime Primary Care Visits Due to Asthma Attack , 2009, Journal of epidemiology.

[9]  A. Biggeri,et al.  Susceptibility factors to ozone-related mortality: a population-based case-crossover analysis. , 2010, American journal of respiratory and critical care medicine.

[10]  A. Tobías,et al.  Case-Crossover Analysis of Air Pollution Health Effects: A Systematic Review of Methodology and Application , 2010, Environmental health perspectives.

[11]  J. Jaakkola,et al.  Case-crossover design in air pollution epidemiology , 2003, European Respiratory Journal.

[12]  Scott L Zeger,et al.  On the equivalence of case-crossover and time series methods in environmental epidemiology. , 2007, Biostatistics.

[13]  P. Villeneuve,et al.  Outdoor air pollution and emergency department visits for asthma among children and adults: A case-crossover study in northern Alberta, Canada , 2007, Environmental health : a global access science source.

[14]  Brian H Rowe,et al.  Air pollution and emergency department visits for cardiac and respiratory conditions: a multi-city time-series analysis , 2009, Environmental health : a global access science source.

[15]  C. Paulu,et al.  Tracking associations between ambient ozone and asthma-related emergency department visits using case-crossover analysis. , 2008, Journal of public health management and practice : JPHMP.

[16]  J. Koenig,et al.  Relationship between visits to emergency departments for asthma and ozone exposure in greater Seattle, Washington. , 2009, Annals of allergy, asthma & immunology : official publication of the American College of Allergy, Asthma, & Immunology.

[17]  R. Burnett,et al.  Association Between Ozone and Respiratory Admissions Among Children and the Elderly in Vancouver, Canada , 2003, Inhalation toxicology.