The Lancet Planetary Health | 19 January 2021

'We [the authors] aimed to estimate the proportion of annual preventable deaths due to air pollution in almost 1000 cities in Europe.
A considerable proportion of premature deaths in European cities could be avoided annually by lowering air pollution concentrations, particularly below WHO guidelines. The mortality burden varied considerably between European cities, indicating where policy actions are more urgently needed to reduce air pollution and achieve sustainable, liveable, and healthy communities. Current guidelines should be revised and air pollution concentrations should be reduced further to achieve greater protection of health in cities.'
https://www.thelancet.com/journals/lanplh/article/PIIS2542-5196(20)30272-2/fulltext