Exploring the impact of livestock on air quality: A deep dive into Ammonia and particulate matter in Lombardy

The linkage between agricultural activities, particularly livestock farming, and atmospheric pollution is broadly acknowledged, and its magnitude is widely analyzed. Lombardy, one of Europe's most critical areas with regard to air pollution, has significantly large contributions from the farming industry. Although studies aimed at informing policy reflect uncertain and moderate pollution reduction even under simulated stringent policy scenarios, granular causal evidence at a sub-sector level remains insufficient to inform local and regional policies effectively. In this study, we employ a spatially and temporally indexed econometric model to investigate the specific impact of bovine and swine farming on the concentration levels of ammonia (NH3) and coarse particulate matter (PM10) in Lombardy's atmosphere. Our findings indicate that an increase of 1000 units in livestock, equating to roughly a 1% and 0.3% rise in the average per-quadrant bovine and swine populations, respectively—triggers a corresponding daily increase in NH3 and PM10 concentrations. These increases are quantified as 0.26 [0.22; 0.33] and 0.29 [0.27; 0.41] μg/m3 for bovines (about 2% and 1% of the respective daily averages) and 0.01 [0.01; 0.05] and 0.04 [0.004; 0.16] μg/m3 for swine. Notably, these impacts are intensified under northerly upwind conditions, minimizing the potential for concurrent pollution sources and reinforcing the robustness of our estimated impacts. Finally, we employ our findings to extrapolate the potential environmental implications of reducing livestock emissions. Our analysis suggests that bovine and swine farming could account for up to 25% of local pollution exposure, empathizing the need for targeted mitigation strategies.