Europe will struggle to meet the new WHO Air Quality Guidelines

Abstract The World Health Organization (WHO) updated its Global Air Quality Guidelines in 2021 due to growing evidence on adverse health impacts of air pollution even at low concentrations. We used a suite of regional atmospheric chemistry models to simulate fine particulate matter (PM 2.5 ) and ozone (O 3 ) levels over Europe in 2015–2050 and assessed the compliance of European countries with the new guidelines under different emission scenarios. The results show that 65% of the EU countries will comply with the PM 2.5 target value (5 µg m −3 ) by 2050 under ambitious emission reductions (SSP1-2.6). Under less ambitious mitigation scenarios (SSP2-4.5 and SSP3-7.0), the compliance level is only 10%. In addition, none of the EU countries will comply with the O 3 target value (60 µg m −3 ), while interim values are achieved in most of the EU countries, partly under SSP2-4.5, and to a large extent under SSP1-2.6. These results highlight that reaching the new WHO limit values will be challenging for Europe, partly due to natural contribution to PM 2.5 reaching up to 50% in some regions. Our findings imply the necessity of more drastic emission reductions to meet the targets.