9 September 2024Work-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 P M 2.5 concentrations, the most harmful air pollutant globally, using high-resolution pollution data and employment records from France. We find that WFH increases P M 2.5 levels, especially in areas with many home-based workers. Residential emissions surpass reductions in transport pollution, leading to a net rise in air pollution. These findings highlight the need for policies to address the environmental challenges of WFH, particularly through energy efficiency and cleaner heating technologies.