# Local approach to attributable disease burden: a case study on air pollution and mortality in Belgium

## TL;DR

This study introduces a local method to estimate air pollution-related deaths in Belgium and shows it aligns closely with traditional national-level estimates.

## Contribution

A novel local approach for estimating air pollution mortality at census tract level, validated against global methods.

## Key findings

- Local estimates for PM2.5 and NO2-related deaths in Belgium align closely with global estimates, with deviations under 4%.
- The concentration-response function contributes most to overall uncertainty in mortality estimates.
- The local method allows for flexible, subnational analysis of disease burden for policy and research.

## Abstract

Burden of disease estimation and the attribution to risk factors are commonly done on national or regional scale. This research proposes a novel approach, where air pollution-related mortality in Belgium was estimated locally, and compares the results to those of the common ‘global’ approach.

In the local approach, mortality attributable to long-term exposure to particulate matter < 2.5 μm (PM2.5) and nitrogen dioxide (NO2) is derived at the level of census tracts. Relying on a statistical concentration-response function suggests potential bias when applied to such small scale. Therefore, the local method is validated by comparing aggregated results to estimates derived with a global approach. In a sensitivity analysis, the difference between the global and local approach is compared to the impact of other methodological choices and sources of uncertainty.

The local method estimates (95% confidence interval) 12,276 (6,695; 17,826) deaths for PM2.5 and 7,944 (4,725; 11,181) for NO2 in Belgium. For both pollutants, these national estimates never deviate more than 2% from those obtained with the global method, and never more than 4% in the individual provinces. The sensitivity analysis demonstrates the concentration-response function as having the largest contribution to overall uncertainty, while the global-local discrepancy is slightly larger compared to the exposure uncertainty.

Aggregated local burden estimates prove to be accurate compared to the global approach. This means the local method shows potential for comparing areas and population groups at subnational level, where estimates can be generated in a flexible manner depending on research or policy needs.

The online version contains supplementary material available at 10.1186/s12889-025-23625-z.