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Air pollution and long-term risk of hospital admission due to chronic obstructive pulmonary disease exacerbations in Poland: a time-stratified, case-crossover study

Piotr Dąbrowiecki, Andrzej Chciałowski, Agata Dąbrowiecka, Anna Piórkowska, Artur Badyda
Published online: February 27, 2023


Introduction: Airborne pollutants may worsen the course of chronic obstructive pulmonary disease (COPD). Previous studies have shown that both particulate and gaseous pollutants increase airway inflammation, which may lead to an exacerbation of COPD.

Objectives: To study the association between exposure to airborne pollutants and the risk of COPD exacerbations in the three largest urban agglomerations in Poland: Warsaw, Cracow, and the Tricity.

Patients and methods: We used a case-crossover approach to analyze data from 2011 to 2018. This time-series study used distributed lag nonlinear models to analyze the risk of hospital admission due to COPD exacerbations during 21 days following exposure to particulate matter (PM), NO2, and SO2.

Results: Overall, there were 26,948 admissions due to COPD exacerbations. During 21 days after exposure, the rate ratio (95% confidence interval) for admissions per 10 µg/m3 was 1.028 (1.008-1.049) for PM10; 1.030 (1.006-1.055) for PM2.5; 1.032 (0.988-1.078 for NO2; and 1.145 (1.038-1.262) for SO2. The risk for admission peaked at 10 days after exposure to PM10 and PM2.5, whereas for NO2 and SO2 the risk was greatest on the day of exposure. The proportions (95% confidence interval) of hospitalizations attributable to air pollution were 9.08% (3.10%-15.08%) for PM10; 7.61% (1.27%-13.49%) for PM2.5; 9.77% (3.63%-21.48%) for NO2; and 7.70% (2.30%- 12.84%) for SO2.

Conclusions: PM2.5, PM10, NO2, and SO2 pollution was associated with an increased risk of COPD exacerbations that needed treatment in hospital. There were different risk patterns for particulate and gaseous pollutants. Improving air quality in Polish cities could reduce the burden of COPD.

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