5: How London’s Ultra Low Emission Zone has reduced air pollution

In April 2019, London launched its first Ultra Low Emission Zone (ULEZ), which operates in the existing central London Congestion Charge Zone. By implementing stricter emission standards, the aim of the ULEZ is to reduce the number of old, polluting vehicles circulating in the central zone, and therefore improve air quality. The evaluation of the first six months of the zone showed significant progress32 (although some improvements reflect the impact of the Toxicity Charge introduced in 2017):

  • Increase of the average compliance rate with ULEZ standards from 39 per cent in February 2019 to 77 per cent in September
  • Reduction of 36 per cent of NO2 concentration in central London between February 2017 and September
  • Reduction of NO2 concentration equivalent to 29 per cent in central London, compared to a scenario with no ULEZ , based on average data between July and September
  • Reduction of nitrogen oxides emissions from road transport in the central zone by 31 per
  • Reduction in the number of polluting and non-compliant vehicles in the zone by 38 per cent, which corresponds to 13,000 fewer on an average

London has also introduced a near £50 million scrappage scheme to incentivise people to switch to cleaner vehicles, allocating £25 million for low-income motorists, in addition to an existing £23 million scrappage scheme for micro-businesses, sole traders and charities.


  • 32 GLA (2019), Central London Ultra Low Emission Zone – six month report, London: GLA.