26 January 2026Work-from-home (WFH) arrangements experienced an unprecedented boom since the Covid-19 crisis, raising questions about their environmental impact. This study investigates the causal effect of WFH on PM2.5 concentrations, the most harmful air pollutant globally, using high-resolution pollution data and employment records from France. We find that WFH contributes to higher PM2.5 levels, particularly in areas with a high prevalence of home-based workers. Our analysis reveals that residential emissions outweigh the reduction in transport-related pollution, leading to a net increase in air pollution. These findings highlight the need for policymakers to address the environmental challenges associated with the growing prevalence of WFH, particularly through energy efficiency improvements and cleaner residential heating technologies.