Background - The reduction in socioeconomic activity resulting from the lockdown implemented to limit the spread of COVID-19 in the spring of 2020 led to decreases in ambient air pollutant concentrations. Methods - The quantitative health impact assessment (EQIS) method was used to estimate the impact on mortality in the French population in terms of: 1/ short-term and longer-term consequences of reductions in levels of particulate matter (PM10 and PM2.5) and nitrogen dioxide (NO2) during the lockdown, and 2/ long-term estimation of the total burden of pollution over the 2016–2019 period. Results - The restriction of socioeconomic activities in the spring of 2020 led to a reduction in the French population’s exposure to NO₂ and fine particulate matter, which prevented approximately 2,300 deaths linked to PM and nearly 1,200 linked to NO₂. The long-term impact of pollution on mortality is estimated at nearly 40,000 annual deaths linked to PM2.5 and nearly 7,000 deaths attributable to NO2 exposure. Conclusion - These results provide further evidence confirming that even short-term public measures to reduce sources of air pollution lead to immediate benefits in terms of population exposure and health impacts. Public measures—other than lockdowns, which are obviously undesirable—thus constitute an effective lever for improving ambient air quality and public health. Furthermore, the results highlight that, in the long term, mortality linked to air pollution remains a significant risk factor in France and that efforts to reduce pollution must be sustained over the long term across all sources, with a transition that is appropriate yet ambitious.