Is air pollution a risk factor for sleep-disordered breathing in children? A study in the province of Varese

The role played by air pollutants on sleep-disordered breathing (SDB) in childhood thus far has been little analyzed, although susceptibility to environmental toxicity is higher in children than in adults. This ecological study, carried out in the province of Varese, Italy, explores the geographical pattern of SDB among children and investigates its relationship with combustion-related pollution. For each of the 754 patients admitted to the Sleep-Disorder Breathing Center of Varese due to sleep respiratory disturbances, the apnea-hypopnea index (AHI) upon which SDB diagnosis is based was recorded. Through spatial analysis methods, the geographical heterogeneity of SDB and its severity were analyzed using AHI-based indicators. From available nitrogen dioxide (NO2) levels, the geographical pattern of the pollutant--regarded as a marker for combustion-related mixtures--was obtained and compared with that of SDB. We identified an area of significantly higher SDB case density (p < .05) and found that the relative risk (RR) of SDB increased significantly for the children living in this area (RR = 1.307, 95% confidence interval [CI] [1.155, 1.477]). In this area, annual NO2 levels were 1.5 times the provincial average. For the whole study region, moreover, we found a significant positive correlation (p < .01) between SDB severity and NO2. These findings suggest that traffic-related pollution might contribute to SDB onset and level of severity.