Ambient Air Pollution and Cardiorespiratory Events in High-Risk Infants Using Home Monitors

Abstract

TM6-O-01 Session Title: Air Pollution: Short-term Cardiovascular Effects Introduction: Identifying populations that are susceptible to the acute adverse health effects of ambient pollutants is a priority in air pollution research. The few studies that have examined infants suggest that ambient air pollution levels are associated with cardiorespiratory outcomes in this age group, but the studies have been generally limited in power and in health outcome information. The associations of daily ambient air pollution levels with apnea and bradycardia were examined in infants prescribed home cardiorespiratory monitors from 1998 through 2002, followed at one of the largest referral centers for home monitoring in the country. This is a novel population for air pollution studies and allows for examination of a potentially susceptible group. Methods: The monitors record the electrocardiogram, heart rate, and impedence for detected events. Collected data include type, date, time, and duration of each event, gender, date of birth, gestational age at birth, and birth weight. We assessed these events in relation to speciated particulate matter levels as well as gaseous air pollution levels, using a 2-day average of air pollution lagged zero and one day. Odds ratios (OR) and confidence intervals (CI) were calculated per standard deviation increase in pollution levels. Results: In preliminary analyses, 4277 infants had 8960 apnea event-days and 29,450 bradycardia event-days in over 179,000 days of follow-up. Our analysis used generalized estimating equations, controlling for time trends, temperature, age of the infant, weekends, and federal holidays as well as residual correlation within subject. Preliminary results show associations between bradycardia and ozone (OR, 1.049 per 25 ppb; 95% CI, 1.021–1.078) and nitrogen dioxide (OR, 1.025 per 20 ppb; 95% CI, 1.000–1.050). The association with ozone was robust to various methods of control for time trend and specified correlation structure. Associations with other pollutants, as well as associations for apnea events, were consistent with a null association. In secondary analyses, apnea events in full term and normal birth weight infants were associated with increased levels of the organic carbon component of fine particulate matter (OR = 1.091 per 2 μg/m3, 95% CI, 1.002–1.186); associations for preterm and low birth weight infants were consistent with a null association. Discussion: These results suggest that infants who are at high risk for apnea and bradycardia may be susceptible to the adverse health effects of ambient air pollution.