London's air quality has seen substantial improvements over the past decade, with average nitrogen dioxide (NO₂) levels decreasing by almost 38% since 2014. All neighbourhoods in the capital now meet the UK's legal limit of 40 micrograms per cubic meter (μg/m³) for annual average NO₂.
Despite these improvements, fewer than 1% of London's neighbourhoods meet the World Health Organization's (WHO) recommended guideline of 10 μg/m³. Analysis shows that while more deprived areas and those with larger non-white populations experienced some of the biggest reductions in air pollution, they started with much higher levels and continue to be among the most polluted parts of London.
Rosamund Adoo-Kissi-Debrah, whose daughter Ella became the first person in the UK to have air pollution listed on her death certificate, stated that while the Ultra Low Emission Zone (Ulez) has been beneficial, "there is still so much more to do." A spokesperson for the Mayor of London, Sir Sadiq Khan, also noted that while Londoners are breathing cleaner air, further action is needed.
The Department for Environment, Food and Rural Affairs (Defra) has stated the government is committed to reducing harmful pollution through measures including cleaner transport and tighter emissions standards. Research indicates that the Ulez and its predecessor, the T-Charge, have been associated with reductions in emergency hospital admissions and an estimated 40% fall in air pollution-linked deaths in London over five years from 2019.