The introduction of London’s Ultra Low Emission Zone (ULEZ) has been linked to fewer people being admitted to hospital, providing some of the clearest evidence yet that cutting air pollution can directly improve public health.

That comes from a study by researchers at Imperial College London that found that London’s ULEZ and the earlier T-charge schemes were associated with a reduction in hospital admissions, adding to growing evidence that efforts to cut vehicle emissions are delivering measurable health benefits.

The researchers found that after the introduction of the T-charge in 2017 and the central London Ultra Low Emission Zone (ULEZ) in 2019, hospital admissions fell for a range of conditions linked to exposure to air pollution. The strongest effects were seen for cardiovascular disease, with admissions declining by 9.3% per year compared with a control area in outer London.

All-cause hospital admissions also fell by 5.1%.

ULEZ was introduced in central London in 2019, replacing the earlier T-charge scheme, which targeted the most polluting vehicles. Since then, the zone has been expanded first to the North and South Circular roads in 2021 and then across all of Greater London in 2023.

Although previous studies have naturally found that the air is indeed cleaner now, evidence of direct health benefits has been more limited.

To assess the impact on public health, the Imperial researchers analysed hospital admission data from January 2014 to March 2020, comparing trends before and after the introduction of the T-charge and central London ULEZ. The study ended before the COVID-19 pandemic, which significantly altered travel patterns and air pollution levels.

The analysis focused on emergency hospital admissions among adults for cardiovascular disease, respiratory disease and all causes combined — conditions known to be affected by short-term exposure to air pollution.

Initially, the study found annual reductions of 8.1% in cardiovascular admissions, 6.2% in respiratory admissions and 3.1% in all-cause admissions within the central London intervention area. When researchers compared the results with a control area in outer London to account for wider healthcare and demographic trends, the reductions remained significant for cardiovascular disease and all-cause admissions.

The findings suggest that reducing vehicle emissions does more than improve air quality statistics. It appears to be reducing the number of people becoming ill enough to require emergency hospital treatment, easing pressure on hospitals while improving health outcomes for Londoners.

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The research was supported by funding from the Medical Research Council (MRC), MRC Centre for Environment and Health, the National Institute for Health and Care Research (NIHR) Health Protection Research Unit in Chemical and Radiation Threats and Hazards.

The work was also supported by the NIHR Imperial Biomedical Research Centre, a translational research partnership between Imperial College Healthcare NHS Trust and Imperial College London.

The full paper is here.