This study proposes to assess the potential health benefits of LEZs for the population of the Paris region by taking into account individual levels of exposure to air pollution during travel and activities during the day. Dynamic maps of NO2 concentration, a household travel survey and a road traffic model are used to assess the population exposed to air exceeding 40 μg/m3 of NO2. The impact of LEZ implementation in the Paris region would be smallest for those populations that are most sensitive to pollution problems, the youngest and oldest. The wealthiest would be the big winners from the LEZ, but were also the most exposed. According to scenarios, between 13 and 43% of residents who were exposed to high NO2 concentrations outside the LEZ perimeter fell below the critical threshold of 40 μg/m3.