In many countries higher concentrations of harmful air pollutants coincide with more deprived areas of society, where prevalence of health impacts associated with air pollution are greater. However, the impact of policies aimed at mitigating air pollution on the bias in exposure across deprivation groups rarely feature in policy development.

We introduce the Indicator of Exposure Bias (IoEB) to the UK Integrated Assessment Model to quantify this bias, providing a method for comparing different scenarios and sectors. We analyse the bias in exposure to PM2.5 concentrations across deprivation levels within England currently and for future scenarios, and by sectors. While England's Index of Multiple Deprivation (IMD) and the Health domain are used as measures of deprivation here, the indicator can be applied to any pair of spatial socio-economic status and environmental exposure metrics.

An IoEB of 0.88 µg.m−3 was calculated for the 2018 baseline, indicating a bias in exposures towards more deprived areas ranked using the IMD. All future scenarios considered here lead to reductions in population exposure and a reduction in the bias towards more deprived areas, with the greatest reduction of 59 % achieved by focusing on urban sources of primary PM2.5. The total bias in exposure towards more deprived areas is mitigated by an opposite bias for the transboundary contribution, therefore the bias in exposure of total PM2.5 does not accurately reflect that associated to UK anthropogenic emissions. The bias varies significantly between sectors, with non-industrial combustion and road transport the greatest contributors.

Reaching England's 2040 PM2.5 exposure target is likely to deliver substantially greater health benefits for the more deprived members of society than the less deprived, reducing health inequality. The bias is sensitive to the measure of deprivation used, demonstrated using the Health domain.