Taxes on products considered polluting are struggling to gain ground in the EU despite backing from Brussels, in the face of opposition from movements like France's "Yellow Vests".
Electric vehicles took centre stage at this year's Geneva Motor Show, as automakers scrambled to bring their fleets into line with strict CO2 emissions standards set to kick in next year.
Some 385,000 people worldwide died prematurely in 2015 from air pollution caused by vehicle exhaust emissions, a US study has found, singling out diesel engines as the main culprit.
Which European cities have the worst air quality? This interactive graphic shows where the concentration of nitrogen dioxide is the highest.