Influence of air pollutants on risk of asthma admission in 3 largest urban agglomerations in Poland

<bold>Objective:</bold> Ambient air pollution is a serious public health problem in Poland (e.g. the highest PM_2.5 levels in the EU). Various studies have shown that both solid and gaseous pollutants can cause asthma exacerbations. The aim of the study was to define the association between the exposure to various air pollutants and the risk of asthma hospital admission. <bold>Materials and Methods</bold>: We used a time-series analysis to find the association between the exposure and asthma (ICD-10 codes J45/J46) hospitalization in 3 largest urban agglomerations in Poland: Warsaw, Cracow and the Tricity in 2010-2018. A distributed lag nonlinear models were used to analyze the delayed associations of PM₁₀, PM_2.5, NO₂, and SO₂ with asthma admission risk during 7 days following the exposure. <bold>Results:</bold> 31,919 asthma hospitalizations were identified. During 7 days after exposure a PM₁₀ increase of 10 µg/m³ was associated with an increased admission risk of 1.013 (95%CI: 1.002-1.024). For PM_2.5 and NO₂ the risk was 1.014 (1.000-1.028) and 1.54 (1.031-1.078) respectively. It was insignificant for SO₂. The proportions (95% CI) of hospitalizations attributable to air pollution were 4.52% (0.80%-8.14%) for PM₁₀, 3.74% (0.29%-7.11%) for PM_2.5, 16.4% (10.0%-21.8%) for NO₂ and 2.50% (0.75%-5.36%) for SO₂. The risk of admission peaked on the day of exposure, decreased below the baseline on days 2-3 and then increased up to days 6-7. <bold>Conclusions:</bold> Exposure to PM, NO₂ and SO₂ was associated with an increased risk hospital admission due to asthma exacerbation. This evidence should push forward initiatives to reduce emissions from individual households in Poland (the main source of PM), and road traffic (the main source of NO₂).