[en] The continuous improvement of air quality in the region of Ile-de-France has saved many lives. However, the negative impact observed remains substantial. For more than 30 years, the regional health observatory (Observatoire regional de sante, ORS) in Ile-de-France has supported public policies to improve air quality by carrying out quantitative health impact assessments (QHIA). Conducted in partnership with Airparif, the present study aimed to qualify mortality over the 10 past years in Ile-de-France due to human-induced air pollution and to estimate the benefits should the concentrations observed in 2019 be reduced according to WHO recommendations. We also investigated the impact of restrictions enforced in 2020 due to the Covid-19 pandemic. This QHIA relies on methodological guides produced by Sante publique France, the French public health agency, and uses the relative risks established in scientific literature. Fine-scale geographic data on PM_2.5, NO₂ and O₃ concentrations (reference years 2008-2010 and 2017-2019) and resident populations were used to estimate the distribution of exposure. We applied the estimated attributable fraction to observed mortality (reference years 2004-2008 and 2011-2015) in order to compute the overall benefits of air-quality improvement in terms of preventable deaths and gains in life expectancy. Between 2010 and 2019, the number of deaths from long exposure to fine particles (PM_2.5), one of the main air pollutants, fell from 10,350 [3,840-15,660] to 6,220 [2,240-9,650], representing a 40% decrease. This is equivalent to an average gain in life expectancy of 8 months per habitant in Ile-de-France. Taking further measures and reducing air pollution to a level under the threshold recommended by the WHO could avoid more than 7,900 [2,240-13,630] deaths per year on average in Ile-de-France, which represents the combined impact of PM_2.5 and O₃ (2019 data). Assessing the health impact of exposure to pollution provides further evidence for public health action. These estimations are useful to inform stakeholders, guide public policies for air-quality improvement, and encourage social acceptability of measures.