Comparison of global air pollution impacts across horizontal resolutions

The impact of ambient air pollution on human health, particularly fine particulate matter (PM 2.5 ) and tropospheric ozone (O 3 ), is a critical global concern. Atmospheric chemical transport models (CTMs) are widely used to predict air pollutant concentrations and assess associated health risks. However, there is a need to better understand how the horizontal resolution of these models influences their accuracy, especially in future assessments. In this study, we compared the performance of global low-resolution CTMs with high-resolution nested simulations for estimating O 3 and PM 2.5 concentrations. The models were validated against observational data to determine their accuracy across different spatial scales and to evaluate their suitability for future scenario assessments. Our findings demonstrate that while the nested-grid simulations improved the reproducibility of regional observations, especially in areas with complex topography or localized emissions, the overall global-scale performance of the model did not significantly benefit from higher resolution. Additionally, the differences in global health and agricultural impacts between low- and high-resolution simulations were minor and within the range of uncertainty typically associated with emission inventories and CTMs. However, for specific regional studies or policy applications, higher resolution may offer improved accuracy. Ultimately, the current low-spatial-resolution model provides sufficient accuracy for many global-scale applications, but the choice of resolution should be carefully considered depending on the specific objectives of the study especially in future scenario. • Low and high-spatial domains simulation to evaluate O3 and PM2.5 and assess the effect of nested-grid outputs. • Validated model outputs against observations and analyzed differences in agricultural and health impacts by resolution. • Increased model resolution improved regional accuracy but had limited impact on global reproducibility. • Differences in global agricultural/health impacts were minor, comparable to uncertainties in emissions inventories and CTMs. • Increased CTM resolution affected regional air pollution estimates, with negligible influence on overall findings.