Low-Level Ozone Exposure and Respiratory Symptoms in Infants
 

 

Elizabeth W. Triche,¹ Janneane F. Gent,¹ Theodore R. Holford,¹ Kathleen Belanger,¹ Michael B. Bracken,^1,2 William S. Beckett,³ Luke Naeher,⁴ Jean-ellen McSharry,¹ and Brian P. Leaderer<sup>1

1</sup>Yale Center for Perinatal, Pediatric, and Environmental Epidemiology, Department of Epidemiology and Public Health, and ²Department of Obstetrics and Gynecology, Yale University School of Medicine, New Haven, Connecticut, USA; ³Departments of Environmental Medicine and Medicine, University of Rochester School of Medicine and Dentistry, Rochester, New York, USA; ⁴Department of Environmental Health Science, College of Public Health, University of Georgia, Athens, Georgia, USA

Abstract
Objective: Recent studies indicate that the U.S. Environmental Protection Agency (EPA) ozone standards may not protect sensitive individuals. In this study we examined respiratory effects of ozone in infants who may be vulnerable, particularly if they are children of asthmatic mothers.

Design: Women delivering babies at one of five hospitals in southwestern Virginia between 1994 and 1996 were invited to participate in a cohort study ; 780 women enrolled. Ambient air quality data (ozone and particulate matter) were collected at a central monitoring site.

Participants: This analysis is of 691 infants followed for approximately 83 days between 10 June and 31 August 1995 and/or 1996 ; they contributed a total of 52,421 infant-days of follow-up. Mothers were interviewed at enrollment and approximately biweekly to report infants' daily symptoms. Repeated measures logistic regression models were run separately for wheeze, difficulty breathing, and cough. Ozone metrics included 24-hr average, peak 1-hr, and maximum 8-hr average. Analyses were repeated for the 61 infants whose mothers had asthma.

Results: For every interquartile-range increase in same-day 24-hr average ozone, likelihood of wheeze increased 37% [95% confidence interval (CI) , 2–84%]. Among infants of asthmatic mothers, same-day 24-hr average ozone increased likelihood of wheeze 59% (95% CI, 1–154%) and of difficulty breathing 83% (95% CI, 42–136%) . Maximum 8-hr ozone and peak 1-hr ozone were associated with difficulty breathing, but not wheeze, in infants of asthmatic mothers. Ozone was not associated with cough.

Conclusions: At levels of ozone exposure near or below current U.S. EPA standards, infants are at increased risk of respiratory symptoms, particularly infants whose mothers have physician-diagnosed asthma.

Key words: air pollution, difficulty breathing, infant symptoms, maternal asthma, wheeze. Environ Health Perspect 114:911–916 (2006) . doi:10.1289/ehp.8559 available via http://dx.doi.org/ [Online 29 December 2005]
http://www.ehponline.org/members/2005/8559/8559.html
 
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