Academic journal article Environmental Health Perspectives

Early-Life Exposure to Outdoor Air Pollution and Respiratory Health, Ear Infections, and Eczema in Infants from the INMA Study

Academic journal article Environmental Health Perspectives

Early-Life Exposure to Outdoor Air Pollution and Respiratory Health, Ear Infections, and Eczema in Infants from the INMA Study

Article excerpt

BACKGROUND: Prenatal and early-life periods may be critical windows for harmful effects of air pollution on infant health.

OBJECTIVES: We studied the association of air pollution exposure during pregnancy and the first year of life with respiratory illnesses, ear infections, and eczema during the first 12-18 months of age in a Spanish birth cohort of 2,199 infants.

METHODS: We obtained parentally reported information on doctor-diagnosed lower respiratory tract infections (LRTI) and parental reports of wheezing, eczema, and ear infections. We estimated individual exposures to nitrogen dioxide (N[O.sub.2]) and benzene with temporally adjusted land use regression models. We used log-binomial regression models and a combined random-effects meta-analysis to estimate the effects of air pollution exposure on health outcomes across the four study locations.

RESULTS: A 10-[micro]g/[m.sup.3] increase in average N[O.sub.2] during pregnancy was associated with LRTI [relative risk (RR) = 1.05; 95% CI: 0.98, 1.12] and ear infections (RR = 1.18; 95% CI: 0.98, 1.41). The RRs for an interquartile range (IQR) increase in N[O.sub.2] were 1.08 (95% CI: 0.97, 1.21) for LRTI and 1.31 (95% CI: 0.97, 1.76) for ear infections. Compared with N[O.sub.2], the association for an IQR increase in average benzene exposure was similar for LRTI (RR = 1.06; 95% CI: 0.94, 1.19) and slightly lower for ear infections (RR = 1.17; 95% CI: 0.93, 1.46). Associations were slightly stronger among infants whose mothers spent more time at home during pregnancy. Air pollution exposure during the first year was highly correlated with prenatal exposure, so we were unable to discern the relative importance of each exposure period.

CONCLUSIONS: Our findings support the hypothesis that early-life exposure to ambient air pollution may increase the risk of upper and lower respiratory tract infections in infants.

KEY WORDS: air pollution, children's health, ear infections, eczema, in utero exposure, respiratory infections. Environ Health Perspect 121:387-392 (2013). http://dx.doi.org/10.1289/ehp.1205281 [Online 5 December 2012]

Asthma, allergies, and respiratory infections are major health issues in childhood, and there is growing evidence that traffic-related air pollution is a risk factor for the development of asthmatic/allergic symptoms and respiratory infections (Braback and Forsberg 2009; Hoek et al. 2012). Ear infections are one of the leading causes of physician visits in young children as a major complication of a preceding upper respiratory infection, and they have been moderately associated with ambient air pollution (Brauer et al. 2006; Macintyre et al. 2011; Zemek et al. 2010). The first years of life are thought to be the most important period for the development of asthma and allergies (Landau 2006). Because both the respiratory and immune systems are still under development, exposure to air pollution during this period may be critical for lasting adverse effects on respiratory health (Bateson and Schwartz 2008).

Most studies investigating the effects of outdoor air pollution on respiratory health, allergic symptoms, and ear infections during early childhood have focused on postnatal exposure, and only some of them have applied air pollution modeling techniques to obtain individual estimates of exposure (Brauer et al. 2002; Gehring et al. 2002; Karr et al. 2009; Macintyre et al. 2011; Morgenstern et al. 2007). There is increasing evidence from experimental and epidemiologic studies that the prenatal period is a critical window for harmful effects of toxic chemicals on respiratory health early in life and beyond (Pinkerton and Joad 2006). However, the effect of air pollution exposure during pregnancy on respiratory health and allergic responses early in life has been examined in only a small number of studies; these differed considerably with regard to exposure assessment and outcome definitions, which included physician records of asthma diagnosis (Clark et al. …

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