Exposure to air pollution and risk of IBD admissions in Poland: a nationwide study with LUR

Background

Inflammatory bowel disease (IBD) incidence is rising in Central and Eastern Europe, while there is a lack of studies considering environmental impacts. We examined the association between long-term exposure to NO₂ and PM10 and IBD hospitalisation rates across 364 Polish administrative districts.

Methods

An ecological study design was performed, using national registry IBD hospitalisation data (ICD-10: K50–K51) covering 134,307 cases, including 50,383 emergency hospital admissions from 2015 to 2019. Long-term exposure to air pollutants was estimated using a Land Use Regression (LUR) model combining: (i) ground-level measurements from 194 national monitoring stations, (ii) CAMS Reanalysis, and (iii) local land cover from ESA WorldCover 2021. Associations were estimated using Negative Binomial regression with population offset, adjusted for population density and forest cover.

Results

The median IBD total hospitalisation rate was 66.7 (IQR 49.7–82.9), including 26.7 (IQR 20.8–31.6) per 100,000/year for urgent admissions. Median LUR-estimated NO₂ was 11.8 µg/m³ (IQR 10.4–12.8), and PM10 was 29.3 µg/m³ (IQR 28.6–30.1). Each IQR increase in NO₂ (1.8 µg/m³) was associated with a 5% higher total IBD hospitalisation rate (IRR 1.05, 95% CI 1.00–1.10; p = 0.046; urgent IRR 1.04, 95% CI 1.00–1.08; p = 0.054), with consistent effects for Crohn’s and UC admissions. Similarly, each mean territorial IQR increase in PM10 (1.5 µg/m³) was associated with a 4% higher total IBD admissions rate, with the same pattern in K50 and K51.

Conclusions

Long-term exposure to NO₂ and PM10 was positively associated with urgent IBD hospitalisation rates across all 364 poviats. These findings support an ecological link between air pollution, the environmental background pattern, and IBD burden, leading to inequality and, in turn, to regional differentiation in medical care needs. These findings underscore the need for spatially refined exposure assessment in environmental epidemiology of IBD.

Key messages

• Long-term exposure to NO₂ and PM10 is associated with increased IBD hospitalisation rates across Poland, with consistent effects for both Crohn’s disease and ulcerative colitis.

• Spatial variation in air pollution contributes to regional inequalities in IBD burden, highlighting the need for refined exposure assessment in environmental epidemiology.