Health and exposure to air pollution
Air pollution refers to harmful gases, solids and liquids in the air. In London, road transport is the main source of pollution, however other sources like wood burning, gas boilers and construction also make significant contributions.
Air pollution affects everyone, but the impact is felt most by vulnerable groups including children, older people and those with heart and respiratory conditions.
People in more deprived areas are also disproportionately affected by poor air quality, often because they live near busier roads.
Fine particulate matter and nitrogen dioxide
The two pollutants of most concern in London are fine particulate matter (PM2.5) and nitrogen dioxide (NO2).
- PM2.5 can harm our heart and lungs. It is linked to asthma and other heart and lung conditions. Research shows that particulate matter is inhaled deep into the lungs, with PM2.5 having a particularly bad impact on health.
- At high concentrations, NO2 can inflame the airways, and long-term exposure can affect lung function and breathing, including by worsening asthma.
The Mayor has committed to aligning with World Health Organization guidelines which reflect current evidence of the health impacts of air pollution. Currently, no location in London meets the final WHO guidelines for PM2.5 or NO2.
Air pollution and health studies
We regularly assess and publish information on the health impacts of air pollution on Londoners.
Imperial College London's Environmental Research Group published a new analysis on the mortality burden of air quality in London which showed that air pollution related deaths decreased by around 40 per cent between 2019 and 2024 - a decrease from around 6,400-8,000 to 3,800-5,100 premature deaths a year.
These improvements reflect a reduction in NO2 levels of 41 per cent, and PM2.5 reductions of 26 per cent as a result of policies including the London-wide ULEZ.
A summary of the literature available on the health impacts of air pollution was published in 2023 can be found here. The report summarises evidence of impacts across the life course, ranging from miscarriage and low birthweight, through childhood asthma and reduced lung growth to mental health and dementia.
In 2022 we published a study by Imperial College London assessing the impact of air pollution in London on hospital admissions for asthma and Chronic Obstructive Pulmonary Disease (COPD).
The report found that, across all age groups, poor air quality led to around 1,700 London hospital admissions for asthma and COPD between 2017 and 2019, with asthma admissions in children accounting for over a third of these admissions. This has reduced from over 4,000 between 2014 and 2016.
A study by Imperial College London, published in 2021, assessed the impact of air pollution and the Mayor’s air quality policies on health, based on 2019 and future levels of air pollution up to 2050.
The report showed that in Greater London in 2019, the equivalent of 3,600 to 4,100 deaths were estimated to be attributable to air pollution. This calculation is for deaths from all causes including respiratory, lung cancer and cardiovascular deaths. This is a reduction from the previous assessment carried out by Kings College London which assessed that in 2010, air pollution was responsible for 9,400 premature deaths in London.
Other key findings from the study include:
- The Mayor’s air quality policies and wider improvements in air pollution will increase the average life expectancy of a child born in London in 2013 by six months.
- The highest number of deaths were in outer London boroughs, mainly due to the higher proportion of elderly people in these areas, who are more vulnerable to the impacts of air pollution. The boroughs with the highest number of air pollution related deaths in 2019 were Bromley, Barnet, Croydon and Havering. This underlines that pollution is not just a central London problem.
Other air quality and health studies include:
- Health Impact Assessment of Current and Past Air Pollution on Asthma in London (2022)
- London Health Burden of Current Air Pollution and Future Health Benefits of Mayoral Air Quality Policies (2021)
- Modelling the Long-Term Health Impacts of Changing Exposure to NO2 and PM2.5 in London (2020)
- Health Impact Assessment of Air Pollution on Asthma in London (2019)
- Understanding the Health Impacts of Air Pollution in London (2015)
Air pollution exposure and inequalities
Air pollution exposure is not equal across London. These inequalities mean air pollution is both a public health issue and a matter of social justice.
Our most recent analysis, Air Pollution and Inequalities in London (2023), examines pollution exposure in London in 2019 by ethnicity, proximity to main roads, boroughs and school locations.
The report shows that:
- the areas in London with the lowest NO2 and PM2.5 concentrations have a disproportionately white population. The inequalities in exposure to air pollution experienced between ethnic groups are much more pronounced in Outer London than Inner London. This inequality has reduced since 2013
- Black, Asian and minority ethnic communities tend to reside in areas where there are higher concentrations of pollutants than the London average.
- for all years analysed between 2013 and 2030, all schools, hospitals and care homes will remain exposed to concentrations of NO2 and PM2.5 above the WHO guideline annual mean, unless further action is taken.
Guidance for Public Health Professionals
Following the Health and Social Care Act, Health and Wellbeing Boards have been set up in each London borough. These boards publish a Health and Wellbeing Strategy, based on the health priorities identified in the borough’s Joint Strategic Needs Assessment.
We have produced guidance for public health professionals which present the latest air quality and health data and analysis for London’s 32 boroughs and the City of London in 33 bespoke reports. Click on the boroughs below to access the guidance.
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