Paris has announced its ‘Crit-Air’ program will see colour-coded stickers applied to diesel vehicles and ban some from entering the city.

Heavy diesel vehicles emit around half the nitrogen oxides (NOx) of diesel cars, per a report released by the International Council on Clean Transportation.

The mayors of four major cities have announced they will ban the use of diesel cars and trucks in Paris, Madrid, Athens and Mexico City by 2025.

Diesel cars have been slammed in a new pollution test showing that nitrogen oxide (NOX) emissions exceed the laboratory results in real-world testing.