The objective of the study was to analyze the relationship between air pollutants and the prevalence of recent symptoms of asthma, allergic rhinitis, and atopic eczema in schoolchildren aged between 6 and 7 years.
The prevalence of recent (previous 12 months) symptoms of allergic diseases was obtained by means of the questionnaire of the International Study of Asthma and Allergies in Childhood (ISAAC), Spain, with the participation of 7 centers (Asturias, Barcelona, Bilbao, Cartagena, La Coruña, Madrid, and Valencia) and 20 455 schoolchildren aged between 6 and 7 years, from 2002 to 2003. The pollutant detection systems of the aforementioned centers provided the mean annual concentrations of sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and total suspended particulate matter.
The annual average concentration of SO2 showed a significant association with a higher prevalence of recent severe asthma (adjusted odds ratio [aOR] between level-1 and level-3 pollution, 1.32; 95% confidence interval [CI], 1.01-1.73), rhinitis (aOR, 1.56; 95% CI, 1.39-1.75), and rhinoconjunctivitis (aOR, 1.70; 95% CI, 1.45-2.00). The annual average concentration of CO was associated with a higher prevalence of rhinitis (aOR, 1.65; 95% CI, 1.34-2.04), rhinoconjunctivitis (aOR, 1.76; 95% CI, 1.31-2.37), and eczema (aOR, 1.55; 95% CI, 1.17-2.04). The annual average concentration for NO2 and total suspended particulate matter showed inverse associations with the prevalence of nocturnal dry cough.
Findings suggest that air pollutants such as SO2 and CO increase the risk of recent symptoms of asthma and allergic rhinitis in schoolchildren aged between 6 and 7 years in Spain.