Early childhood traffic-related air pollution and risk of allergic rhinitis at 2–4 years of age modification by family stress and male gender: a case-control study in Shenyang, China

Background Few studies have explored the modifications by family stress and male gender in the relationship between early exposure to traffic-related air pollution (TRAP) and allergic rhinitis (AR) risk in preschool children. Methods We conducted a case-control study of 388 children aged 2–4 years in Shenyang, China. These children AR were diagnosed by clinicians. By using measured concentrations from monitoring stations, we estimated the exposures of particulate matter less than 10 μm in diameter (PM10), nitrogen dioxide (NO2), ozone (O3), carbon monoxide (CO), and sulfur dioxide (SO2) in preschool children aged 2–4 years. After adjusted potential confounding factors, we used logistic regression model to evaluate the odds ratio (OR) and 95% confidence interval (CI) for childhood AR with exposure to different air pollutants according to the increasing of the interquartile range (IQR) in the exposure level. Results The prevalence of AR in children aged 2–4 years (6.4%) was related to early TRAP exposure. With an IQR (20 μg/m3) increase in PM10 levels, an adjusted OR was significantly elevated by 1.70 (95% CI, 1.19 to 2.66). Also, with an IQR (18 μg/m3) increase in NO2, an elevated adjusted OR was 1.85 (95% CI, 1.52 to 3.18). Among children with family stress and boys, PM10 and NO2 were positively related to AR symptoms. No significant association was found among children without family stress and girls. Conclusions Family stress and male gender may increase the risk of AR in preschool children with early exposure to PM10 and NO2.