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JAMA. 2003 Oct 8;290(14):1859-67.

Association of low-level ozone and fine particles with respiratory symptoms in children with asthma.

Author information

  • 1Center for Perinatal, Pediatric, and Environmental Epidemiology, Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, Conn 06510, USA. janneane.gent@yale.edu

Abstract

CONTEXT:

Exposure to ozone and particulate matter of 2.5 microm or less (PM2.5) in air at levels above current US Environmental Protection Agency (EPA) standards is a risk factor for respiratory symptoms in children with asthma.

OBJECTIVE:

To examine simultaneous effects of ozone and PM2.5 at levels below EPA standards on daily respiratory symptoms and rescue medication use among children with asthma.

DESIGN, SETTING, AND PARTICIPANTS:

Daily respiratory symptoms and medication use were examined prospectively for 271 children younger than 12 years with physician-diagnosed, active asthma residing in southern New England. Exposure to ambient concentrations of ozone and PM2.5 from April 1 through September 30, 2001, was assessed using ozone (peak 1-hour and 8-hour) and 24-hour PM2.5. Logistic regression analyses using generalized estimating equations were performed separately for maintenance medication users (n = 130) and nonusers (n = 141). Associations between pollutants (adjusted for temperature, controlling for same- and previous-day levels) and respiratory symptoms and use of rescue medication were evaluated.

MAIN OUTCOME MEASURES:

Respiratory symptoms and rescue medication use recorded on calendars by subjects' mothers.

RESULTS:

Mean (SD) levels were 59 (19) ppb (1-hour average) and 51 (16) ppb (8-hour average) for ozone and 13 (8) microg/m3 for PM2.5. In copollutant models, ozone level but not PM2.5 was significantly associated with respiratory symptoms and rescue medication use among children using maintenance medication; a 50-ppb increase in 1-hour ozone was associated with increased likelihood of wheeze (by 35%) and chest tightness (by 47%). The highest levels of ozone (1-hour or 8-hour averages) were associated with increased shortness of breath and rescue medication use. No significant, exposure-dependent associations were observed for any outcome by any pollutant among children who did not use maintenance medication.

CONCLUSION:

Asthmatic children using maintenance medication are particularly vulnerable to ozone, controlling for exposure to fine particles, at levels below EPA standards.

Comment in

PMID:
14532314
[PubMed - indexed for MEDLINE]
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