Low-Level Ozone Exposure and Respiratory Symptoms in Infants

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Children's Health

by EHP

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Low-Level Ozone Exposure and Respiratory Symptoms in Infants

W. Triche,1 Janneane F. Gent,1 Theodore R. Holford,1

Kathleen Belanger,1 B. Bracken,1,2 S. Beckett,3 Luke

Naeher,4 Jean-ellen McSharry,1 and P. Leaderer1

1Yale 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]