Background: Long-term exposure to ambient air pollution, in particular fine particles or PM2·5, is a leading global disease burden. PM2·5 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 PM2·5 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.
Methods: For this modelling study, we used the GEOS-Chem model nested over the UK to simulate ambient PM2·5 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 PM2·5 and risk for PM2·5 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.
Findings: We estimated that adult premature mortality attributable to exposure to ambient PM2·5 in the UK totalled 48 625 deaths in 2019 (95% CI 45 118-52 595); 15 000-20 000 more deaths than those estimated using outdated health-risk assessment models.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).
Interpretation: According to our findings, PM2·5 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 PM2·5, in particular the unregulated agricultural sector.
Funding: Department for the Environment, Food and Rural Affairs (DEFRA).
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