Typically, these zones have been most prominently seen around Europe, with the most notable LEZs covering cities in the UK, Germany and Netherlands. The City of London, which currently has the largest LEZ in the world, has already seen a
44 percent drop in NO2 concentration in the air since implementing the Ultra Low Emission Zone in 2017. This has shown great promise for other cities looking to clean up their air supply and give citizens a healthier living environment.