The health burden of air pollution in the UK: a modelling study using updated exposure-risk associations

Long-term exposure to ambient air pollution, in particular fine particles or PM_2·5, is a leading global disease burden. PM_2·5 in the UK, dominated by agricultural emissions of ammonia (NH₃), has been estimated to be responsible for 29 000-34 000 adult early deaths a year. These estimates use models that relate exposure to health risk that predate cohort studies that have identified a supralinear relationship between exposure and risk at relatively low PM_2·5 concentrations typical of the UK (5-12 mg m^-3). Here we used this new knowledge to estimate adult premature mortality in the UK in 2019.

For this modelling study, we used the GEOS-Chem model nested over the UK to simulate ambient PM_2·5 concentrations, UK Office for National Statistics (ONS) health data provided by the Global Burden of Disease (GBD), and a hybrid health-risk assessment model. The hybrid model fuses a well established linear relationship between PM_2·5 and risk for PM_2·5 exceeding 10 mg m^-3 with a supralinear curve at lower concentrations that is constrained with cohort studies conducted in Canada and confirmed with similar relationships from cohort studies in the USA and Europe.

We estimated that adult premature mortality attributable to exposure to ambient PM_2·5 in the UK totalled 48 625 deaths in 2019 (95% CI 45 118-52 595); 15 000-20 000 more deaths than those estimated using outdated health-risk assessment models. Older people (aged 65 years or older) account for most UK deaths (86%). All adult premature mortality (in people aged 25 years and older) in Greater London (4861, 95% CI 4549-5247) exceeded that in Scotland (3673, 3214-4073), Wales (2462, 2270-2660), and Northern Ireland (1052, 934-1156).

According to our findings, PM_2·5 is more hazardous to UK adults than previously reported, but a supralinear exposure-response curve also suggests that there are substantial public health gains in targeting dominant source contributors to PM_2·5, in particular the unregulated agricultural sector.

Department for the Environment, Food and Rural Affairs (DEFRA).