Citizen Scientists Fighting Milan's Smog

Founded in 2015 in Milan, Cittadini per l'Aria recruits volunteer "citizen scientists" to hang low-cost NO2 diffusion tubes outside their homes, schools and workplaces across Italian cities as part of its "NO2, No Grazie!" campaign, recognized as a European Environment Agency best practice since 2017. Analysis of that citizen-collected data, published in 2021 with researchers from the University of Milan, estimated that nitrogen dioxide pollution contributes to roughly 1,500 premature deaths a year in Milan alone, with residents breathing average concentrations of 41.6 micrograms per cubic meter, above the EU legal limit. The group's mapping has fed into Milan's decisions to expand its low-emission traffic zone, and it pursues legal action against national and regional authorities over air-quality failures.