CONCLUSIONS: These results suggest that higher air pollution concentrations may increase the occurrence of apnea and bradycardia in high-risk infants.
The monitors use preset parameters to recognize apnea and bradycardia events; an audible alarm sounds when an event is detected.
The probability of both apnea and bradycardia decreases with increasing age, so a quadratic term for chronologic age was included in the model.
We also stratified the subjects by gestational age and birth weight to evaluate heterogeneity of the estimated associations of air pollution and apnea and bradycardia: infants with gestational age [less than or equal to] 37 weeks and birth weight [less than or equal to] 2,500 g [premature/ low birth weight (LBW)] versus infants with gestational age [greater than or equal to] 37 weeks and birth weight [greater than or equal to] 2,500 g infants [term/normal birth weight (NBW)j.
The number of apnea and bradycardia events per the number of subjects monitored each day as well as the number of infants monitored each day was stable over the study period (data not shown).
ORs and 95% CIs per SD increase in pollution concentration from the primary GEE unconditional logistic regression analyses for apnea and bradycardia using a moving average of pollution lagged 0 and 1 day are presented in Table 4.
In stratified analyses, the associations of air pollution and both apnea and bradycardia among premature/LBW infants (n = 1,367 for apnea; n = 2,289 for bradycardia) were generally weaker than the results from the primary analyses and generally consistent with little or no association [Figures 1 and 2; full numerical results are presented in Supplemental Material, Table 2 (http://dx.doi.org/10.1289/ ehp.
In this study we observed some evidence of acute associations of ambient air pollution with apnea and bradycardia events in infants using home monitors.
This is the first study to examine apnea and bradycardia events in infants in relation to ambient air pollution.
Prolonged apnea and bradycardia in the short term could lead to hypoxic-ischemic injury to the infant's brain; long-term consequences of recurrent events may include neurodevclopmental impairment, although evidence is limited (Stokowski 2005).