Land-use variables and respiratory infections in infancy in the Piccolipiù birth cohort

Abstract

In birth cohort studies, borderline associations have been reported between traffic-related air pollution and otitis, and pneumonia in children. However, the evidence is still scarce, especially in for infants. We aimed to explore the associations of land-use variables at birth and respiratory infections in infants participating in the ongoing prospective Piccolipiù birth cohort recruited in 5 centers in Italy. Of the 3337 infants enrolled, 2698 were studied at 12 months and 1976 at 24 months of age. Occurrence of recurrent upper respiratory infections (URI) including otitis, lower respiratory infections (bronchiolitis, bronchitis, pneumonia), asthmatic bronchitis, and productive cough between birth and 12 months and 12-24 months was ascertained by questionnaires. We investigated road density (meters of roads in the 100m buffer, recoded in quartiles:108-525 [ref]; 525-675; 675-828; 828-1747), major roads density (meters of major roads in the 100m buffer, 0 [ref]; 3.5-203; 203-1654), and distance from major roads (meters, recoded in quartiles: 0-8 [ref]; 8-80; 80-180; 180-2.643). We performed logistic regression, adjusting for center, parental asthma/allergy, maternal education, maternal smoking in pregnancy, siblings, daycare, exposure to passive smoking, dampness and/or mold. Recurrent URI at 12-24 months were associated with road density (higher quartile adjusted OR: 1.88; 95% CI: 1.17; 3.03) and major road density (OR: 1.66; 95% CI: 1.12; 2.47), while an inverse association was found for distance of major roads (higher quartile OR: 0.60; IC 95%: 0.37; 0.98). All trends were significant (P< 0.015). Having siblings and day care attendance were also consistently associated with URI. No associations were found for other respiratory problems. URI are one of the leading causes of physician visits in young children. These data suggest that living near busy roads increases the risk of recurrent URI between 12 and 24 months of life, in addition to known risk factors.