What would be interesting to see is the real gain in life expectancy, not if the WHO threshold was met, but if air pollution rates were further reduced. Gaining a few months of life expectancy does not in fact make you want to make a lot of effort to improve the quality of the air you breathe. I would be very curious to know what our longevity would be if the majority of countries had a score close to Stockolm (among the lowest) for example. The idea is certainly idealistic, but it makes it possible to create a goal to achieve and which really makes one dream. One might ask what would we die of then if not pollution?
Concentration of nitrogen dioxide in France - March 2019, March 14-25, 2020 - European Space Agency