Early childhood lower respiratory illness and air pollution

Abstract

Background: Few studies of air pollutants address morbidity in preschool children. In this study we evaluated bronchitis in children from two Czech districts: Teplice, with high ambient air pollution, and Prachatice, characterized by lower exposures.

Objectives: Our goal was to examine rates of lower respiratory illnesses in preschool children in relation to ambient particles and hydrocarbons.

Methods: Air monitoring for particulate matter < 2.5 microm in diameter (PM(2.5)) and polycyclic aromatic hydrocarbons (PAHs) was conducted daily, every third day, or every sixth day. Children born May 1994 through December 1998 were followed to 3 or 4.5 years of age to ascertain illness diagnoses. Mothers completed questionnaires at birth and at follow-up regarding demographic, lifestyle, reproductive, and home environmental factors. Longitudinal multivariate repeated-measures analysis was used to quantify rate ratios for bronchitis and for total lower respiratory illnesses in 1,133 children.

Results: After adjustment for season, temperature, and other covariates, bronchitis rates increased with rising pollutant concentrations. Below 2 years of age, increments in 30-day averages of 100 ng/m(3) PAHs and of 25 microg/m(3) PM(2.5) resulted in rate ratios (RRs) for bronchitis of 1.29 [95 % confidence interval (CI), 1.07-1.54] and 1.30 (95% CI, 1.08-1.58), respectively; from 2 to 4.5 years of age, these RRs were 1.56 (95% CI, 1.22-2.00) and 1.23 (95% CI, 0.94-1.62), respectively.

Conclusion: Ambient PAHs and fine particles were associated with early-life susceptibility to bronchitis. Associations were stronger for longer pollutant-averaging periods and, among children > 2 years of age, for PAHs compared with fine particles. Preschool-age children may be particularly vulnerable to air pollution-induced illnesses.

Keywords: PAHs; PM2.5; air pollution; bronchitis; children’s health; infant; particulate matter; polycyclic aromatic hydrocarbons; respiratory illness; volatile organic compounds.

Figure 1

Time series for daily PAHs (A) and PM_2.5 (B) in two districts of the Czech Republic, May 1994–August 2003.

Figure 2

Bronchitis RRs and 95% CIs for two air pollutant classes: (A) PAHs and (B) PM_2.5 , for children 0–2 years of age (upper panel for each pollutant) and 2–4.5 years of age (lower panel for each pollutant). In each set of panels, RRs for five averaging periods for the pollutant are presented, with adjustment for each of five averaging periods for mean daily temperature. Rank ordering by goodness of fit (1 = best), calculated from the AIC, is shown by the numerals above the 10 best-fitting models in each panel. Fit statistics spanned a rather tight range. Notably, the strongest associations were not necessarily from the best-fitting models.