Trend analysis of the occurrence of asthma and respiratory symptoms in Polish children over the last 30 years.

<bold>Background:</bold> Recent studies suggest that trends in the occurrence of asthma and respiratory symptoms depend on the region. <bold>Aim:</bold> The aim of this study was to analyse temporal trends in the frequency of respiratory symptoms and associated diseases over the past 30 years in school children from Silesia, Poland. <bold>Methods:</bold> We compared the results of five population-based surveys performed in the town of Chorzow in 1993, 2002, 2007, 2014 and 2023 in children aged 7-10 years. All five studies had the same study protocol, recruitment (cluster, school-based sampling), questionnaire (WHO respiratory health questionnaire), and principal investigator. In 1993, 2002, 2007, 2014 and 2023 the surveys included respectively 1130, 1421, 1661, 1698, and 1595 children. <bold>Results:</bold> The results, covering a 30 year span, showed a statistically significant (p<0.05) increase in the prevalence [%] of asthma diagnosed by physician (3.4, 4.7, 8.4, 12.6, 10.5%), current attacks of dyspnoea (3.9, 5.9, 7.0, 7.3, 6.1%) and respiratory symptoms induced by exercise (7.5, 10.6, 21.4, 22.4, 17.9%); a statistically significant (p<0.05) decrease in the prevalence [%] of morning (36.3, 34.1, 28.0, 24.0, 28.8%) and chronic (31.6, 19.6, 15.4, 14.3, 16.2%) cough. The occurrence of current wheeze was stable (12.3, 14.6, 15.1, 12.1, 14.6%) Conclusions: Our findings confirms a real increase in the occurrence of asthma and symptoms related to respiratory disorders. The reduction in the frequency of coughing may be due to the spectacular improvement in air quality in the study region.