Environmental factors on respiratory symptoms: a cross-sectional study in outpatient children.

Background: Environmental factors play an important role on the worldwide increasing prevalence of respiratory and allergic diseases in children. Aim: to examine the influence of outdoor environmental factors on respiratory symptoms of a sample of outpatient children with Asthma (A) or without Asthma (NA). Methods: Cross sectional study on 302 outpatient children, as a part of the ongoing CHASER study NCT02433275, 3-16 years old, living in Palermo municipality: 96 A; 206 NA visited for suspected allergic respiratory disease at IBIM pediatric clinic (Sept 2011-Dec 2015). Exposure to traffic related air pollution was assessed for each residential address since birth, by using a Land-Use Regression model (LUR) for NO2. Children were geocoded by using a Geographic Information System (GIS) and variable of proximity to high-traffic roads within a 100 m buffer (expressed in thousands of car-km driven per day) was assessed. NO2 and GIS variables were categorized based on the 75th percentile (NO2? 73.32 ?g/m3, HTRs 100 m? 1761.2 car-km). Logistic regression models, adjusted for sex, height and groups, were applied for assessing the relationship between environmental factors and respiratory symptoms obtained by a standardized questionnaire, such as wheezing ever, chronic cough, snoring and exercise induced bronchoconstriction (EIB). Analyses were performed by applying R 3.4.1 software. A p-value<0.05 was considered statistically significant. Results: No differences between A and NA for sex (32 (33.33) vs 71 (34.47), p= 0.949), height (129.53 ± 21.04 vs 133.67 ± 20.06, p= 0.101), weight (32.89 ± 15.73 vs 36.20 ± 16.60, p= 0.101) and atopic status (78 (82.98) vs 156 (78.79), p= 0.495) were found. The average NO2 exposure level was 57.67 ?g/m3 (SD 22.59) exceeding WHO limit values. NO2 and HTRs 100m didn't differ significantly between the 2 groups. With respect to NA, A had more frequently wheezing ever (113 (55.12) vs 77 (81.05) p<0.001) and EIB (45 (23.81) vs 48 (59.26), p<0.001). Irrespective of the A status, significant associations of NO2 with wheezing ever (OR=1.73; CI95%=[1.00, 3.01]) and chronic cough (OR= 4.41; CI95%=[1.86, 10.43]) were found. No significant association with HTRs100m was found. Conclusions: higher traffic related NO2 exposure was associated with increased risk of wheezing and chronic cough in a group of outpatient children living in Palermo. 37