Atmosphere particulate matter and respiratory diseases during COVID-19 in Korea

We aimed to examine the impact of COVID-19 non-pharmaceutical interventions (NPIs) on the relationship between air pollutants and hospital admissions for respiratory and non-respiratory diseases in six metropolitan cities in South Korea. This study compared the associations between particulate matter (PM₁₀ and PM_2.5) and hospital admission for respiratory and non-respiratory diseases before (2016–2019) and during (2020) the implementation of COVID-19 NPIs by using distributed lag non-linear models. In the Pre-COVID-19 period, the association between PM₁₀ and admission risk for asthma and COPD showed an inverted U-shaped pattern. For PM_2.5, S-shaped and inverted U-shaped changes were observed in asthma and COPD, respectively. Extremely high and low levels of PM₁₀ and extremely low levels of PM_2.5 significantly decreased the risk of admission for asthma and COPD. In the Post-COVID-19 outbreak period, the overall cumulative relationship between PM₁₀ and PM_2.5 and respiratory diseases and the effects of extreme levels of PM₁₀ and PM_2.5 on respiratory diseases were completely changed. For non-respiratory diseases, PM₁₀ and PM_2.5 were statistically insignificant for admission risk during both periods. Our study may provide evidence that implementing NPIs and reducing PM₁₀ and PM_2.5 exposure during the COVID-19 pandemic has contributed to reducing hospital admissions for environment-based respiratory diseases.