Abstract
BACKGROUND: Stroke is a leading cause of mortality and disability in Belgium and worldwide. Increasing evidence highlights air pollution as a significant stroke risk factor. Despite efforts in the past decade to mitigate air pollution in Belgium, a considerable part of the population remains exposed to concentrations exceeding the World Health Organization (WHO) Air Quality Guidelines. Therefore, quantifying the effectiveness of further pollution reduction interventions is crucial in supporting policymaking. This study applies a g-computation approach to assess the benefits of hypothetical air pollution reduction scenarios on stroke prevalence in Belgium within a multi-exposure context. METHODS: Belgian health interview survey data (2008/2013/2018, n = 27536) were linked to environmental data at the participant's residential address. Missing data and bias related to self-reported covariates were addressed based on data from the 2018 Belgian health examination survey and a random-forest multiple imputation. A g-computation approach was used to calculate the potential impact fractions of air pollution reduction scenarios on stroke prevalence in Belgium, with regression models adjusted for socio-demographic, environmental, and lifestyle factors. Scenarios included lowering annual exposure to fine particulate matter (PM(2.5)) and nitrogen dioxide levels (NO(2)) to levels recommended by WHO, and assessing dose-response effects of reducing exposure to PM(2.5), NO(2), and black carbon (BC) by 20-80%. RESULTS: Stroke was significantly associated with PM(2.5), while associations with NO(2) and BC were borderline significant. Meeting WHO air quality guidelines for PM(2.5) and NO(2) would reduce stroke risk by 0.88% (SE: 0.24) and 0.33% (SE: 0.19), preventing 67% and 25% of stroke cases in Belgium, respectively. Results reveal a dose-response association between air pollution reduction and stroke prevalence. Reduction in air pollution exposure, ranging from 20% to 80% showed increasing potential impact fractions for stroke: PM(2.5) (29%, 48%, 61%, 69%), NO(2) (10%, 18%, 25%, 31%) and BC (8%, 14%, 20%, 23%). CONCLUSION: This study highlights the importance of air pollution on the stroke burden and demonstrates that air pollution reduction interventions could significantly decrease the prevalence of stroke in Belgium. The g-computation approach represents a straightforward approach in epidemiology for making causal inference from observational data while also providing useful information for policymakers.