Quantifying the climate impacts of the UK achieving the WHO interim PM2.5 target by 2030

Ricardo has carried out an assessment of the greenhouse gas (GHG) impacts of achieving the WHO PM2.5 interim guideline value of 10 µmg-3 (WHO-10) by 2030 funded by the Clean Air Fund. The work built on a previous piece of analysis by Imperial College to define a pathway for achieving WHO-10 by 2030.

The UK 2030 business-as-usual scenario used by Imperial comprised DEFRA’s Business as Usual (BAU) forecast based on BEIS Energy and Emission Projections. The UK 2030 scenario used by Imperial was further adjusted for the road transport sector based on the Climate Change Committee’s 6th Carbon Budget. The current London business-as-usual policy scenario for London’s emissions in 2030 (LS1 scenario) is based on the London Environment Strategy (LES) for the road transport sources and also on the Mayor of London’s roadmap for non-road transport sources. The UK 2030 scenario estimated that the WHO-10 value would be largely achieved across the country with the exception of London in some areas and so two further London focused scenarios were estimated (LS2 and LS3) to estimate compliance in London. The analysis has been carried out at both the national level and for London (as a subset for non-road transport sources) to estimate the co-benefits. 

The objectives of the Ricardo project were to:

• Quantify the climate benefits of the UK achieving WHO-10 by 2030, based on the set of policies identified in the Imperial’s report ‘Pathway to WHO: achieving clean air in the UK. 
• Provide evidence of the climate impacts of air quality actions in the UK to support the debate on the UK’s new PM2.5 target. 
• Develop an initial proof of concept for generating evidence of air quality/climate synergies at a national scale, and quantifying climate impacts of air quality targets and actions.

The analysis indicated that current and proposed government policies related to net zero and air pollution will drive greenhouse gas emissions down by 17% in 2030 from 2018 levels. Additional measures which would achieve the WHO-10 limit value for PM2.5 across the majority of the UK and would also achieve 27% reduction in greenhouse gas emissions. Additional measures in London (LS2 and LS3 scenarios) designed to bring emissions closer to the WHO-10 limit value across the capital were estimated to generate a further 1% reduction (a total reduction of 28% relative to the 2018 levels) in national GHG emissions.

The project demonstrated how such a co-benefits analysis can be done, but clearly illustrated the complexity of this type of assessment.  For example, not all air pollution policies and measures affect greenhouse gases and vice versa, and the scale of impact will not be the same.

A full copy of the report can be download here.