LOWER RESPIRATORY ILLNESSES IN EARLY CHILDHOOD AND EXPOSURES TO FINE PARTICULATES AND PAHs

Abstract

ISEE-153 Introduction: Ambient air pollution increases asthma severity in children, and appears to increase infant mortality, but few studies have addressed early childhood morbidity or the effects from hydrocarbons. In this study, exposures to polycyclic aromatic hydrocarbons (PAHs) and fine particulate matter (PM2.5) in two regions of the Czech Republic were evaluated in relation to incidence of lower respiratory illnesses in early childhood. Methods: A birth cohort, comprising 20% of deliveries between May 1994 and March 1999 in two districts in the Czech Republic, was enrolled. Mothers completed questionnaires about their pregnancy, socio-demographic characteristics, and home environment. Children were followed up at either three or 4.5 years of age (depending on birth year) for collection of pediatric data. Lower respiratory illnesses (LRI) were defined as physician diagnoses for one of twelve ICD (International Classification of Diseases, Tenth Revision) codes. Additionally, acute bronchitis (J20) was examined separately. Parents completed questionnaires regarding indoor air pollution sources, breastfeeding, day care, and other factors potentially related to respiratory illnesses. Analyses were conducted on 1133 children with complete data, covering 1.5 million child-days of observation. Fine and coarse particulates and PAHs were captured using a Versatile Air Pollution Sampler. Daily measurements were made during five winter months of the year, and scheduled third or sixth day measurements were taken in the remaining months. Generalized linear models were used to quantify relationships between each exposure and LRI, and to control for multiple individual risk factors. Rate ratios were estimated using GEE to adjust for repeated measures on the same child and to accommodate time-varying exposures. All associations were estimated for a 100 ng/m3 incremental increase in PAHs or a 25 μg/m3 incremental increase in PM 2.5. Results: Adjusting for multiple covariates, the incidence of LRI, especially bronchitis, increased sharply as average concentrations of PAHs or PM 2.5 over the previous 7 days rose. Between birth and two years, an increment of 100 ng/m3 PAHs and of 25 μg/m3 in PM 2.5 resulted in rate ratios (RRs) of 1.3, 95% ci=[1.2, 1.4] and 1.2 [1.1, 1.3], respectively, for LRI and 1.4 [1.2, 1.5], and 1.3 [1.1, 1.4], respectively, for bronchitis. From two to 4.5 years of age, bronchitis RRs were 1.8 [1.5, 2.2] and 1.4 [1.2, 1.7] for PAHs and PM 2.5, respectively. Adjustment for temperature attenuated results, but RRs remained statistically distinguishable from the null. For instance, adjusted for 3-day average temperature, RRs in the older age group were 1.5 [1.2, 1.8] for PAHs. Conclusion: Increased incidences of LRI generally and especially bronchitis, from birth through the first 4.5 years of life, was associated with weekly average ambient concentrations of PAHs and PM 2.5. The effects are especially strong above two years of age, and are robust to adjustment for ambient temperatures.