Ambient air pollution and hospital admission for interstitial lung diseases: A multicenter hospital-based case-crossover study.

Interstitial lung diseases (ILDs) lead to increased morbidity and premature deaths, imposing a significant burden on public health worldwide. Recently, several studies have linked ambient air pollution with the acute exacerbation of certain ILDs, but the evidence remains limited and inconclusive. With a multicenter hospital-based case-crossover design, we investigated 9128 patients who resided in Jiangsu province, China, and were admitted for ILDs between 2019 and 2022. Residential exposure to particulate matter with an aerodynamic diameter ≤ 2.5 µm (PM2.5), PM10, sulfur dioxide (SO2), nitrogen dioxide (NO2), carbon monoxide (CO), and ozone (O3) was assessed using our validated grid datasets. We fitted conditional logistic regression models to examine associations of exposure to air pollutants with ILD admission. A 10 µg/m3 increment of exposure to SO2 and NO2 was positively associated with a 16.18 % (95 % confidence interval [CI]: 3.79 %, 30.03 %) and 4.06 % (0.75 %, 7.49 %) increase in odds of ILD admission, respectively. All these associations appeared to be linear and the association of SO2 exposure was significantly stronger among older adults. We estimated that over 10 % of ILD admissions could be attributable to exposure to SO2 and NO2. This study provides compelling evidence on the association of exposure to ambient air pollutants (including SO2 and NO2) with an increased odds of ILD hospitalizations. Our findings indicate that SO2 and NO2 exposures can lead to the exacerbation of ILDs, especially in elderly, and that the disease burden is considerable.