Low-level ozone exposure and respiratory symptoms in infants.
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.


METHODS
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.


METHODS
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.
Triche
Elizabeth W
EW
Yale Center for Perinatal, Pediatric, and Environmental Epidemiology, Department of Epidemiology and Public Health, Yale University School of Medicine, New Haven, Connecticut 06520-8034, USA. elizabeth.triche@yale.edu
Gent
Janneane F
JF
Holford
Theodore R
TR
Belanger
Kathleen
K
Bracken
Michael B
MB
Beckett
William S
WS
Naeher
Luke
L
McSharry
Jean-Ellen
JE
Leaderer
Brian P
BP
D015331:Cohort Studies; D004305:Dose-Response Relationship, Drug; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D017063:Outcome Assessment, Health Care; D010126:Ozone / Q000633:toxicity*; D012137:Respiratory System / Q000187:drug effects*
D010126:Ozone