Opposite Trends of Allergic Disorders and Respiratory Symptoms in Children over a Period of Large-Scale Ambient Air Pollution Decline

The aim of our study was to analyze a 15-year trend in the prevalence of allergic disorders and respiratory symptoms in children living in an urban area of Upper Silesia, Poland. Three cross-sectional studies (1993, 2002, and 2007) in children aged 7-10 showed a statistically significant increase in the prevalence of all physician-diagnosed allergic disorders (1993-2002-2007): asthma (3.4%-4.7%-8.5%); allergic rhinitis (9.1%-13.7%-17.4%); atopic dermatitis (3.6%-8.4%-8.9%); allergic conjunctivitis (4.3%-11.8%-14.9%); allergy to pollen (5.9%-12.3%-17.3%); allergy to food (5.5%-11.0%-17.0%). A simultaneous decreasing trend in the prevalence of coughing correlated with significant improvement of ambient air quality. However, the rising trends could result from both increasing incidence and improved diagnosis of allergic diseases.