RTCA Prof Alastair Lewis - Improving air quality through low carbon investments

Transcript

1. Routes to Clean Air 2026 Improving air quality through low carbon investments. Prof. Alastair Lewis Particular thanks to Dr Sarah Moller, Dr Nathan Gray and Lucy Webster at York
2. Decarbonising the UK Don’t waste energy Stop burning stuff Burn green stuff Store carbon
3. Air quality benefits and decarbonisation • Key messages 1) Some very clear win-wins (e.g. renewable electricity) 2 )Try not to burn things to achieve net zero. 3) If you must burn fuels, be cleaner than the incumbent fuel/technology
4. Who benefits, and when, from decarbonisation? • Climate change mitigation doesn’t care where the CO2 is emitted. • All CO2 reductions done today are equally good. • Air quality impact is location-dependant and unevenly distributed. • Some communities experience more air pollution than others, and have worse health outcomes. • Should we target where we decarbonise to help those communities with poorer air quality?
5. Which low carbon investments might improve health? NOx emissions per km2 (2019) Inequalities in air quality– NO2 • • • Electric vehicles clearly vital to future air quality. Decarbonising domestic and industrial combustion is essential Other transport modes and NRMM also important Deprivation based inequality in NOx emissions in England. Gray, N.R., Lewis, A.C. & Moller, S.J., 1 Sept 2023, In: Environmental Science: Advances. 2, 9, p. 1261-1272 12 p.
6. Being deprived isn’t the only factor • Minority ethnicity communities experience higher pollution than white British communities even after the effects of deprivation have been accounted for. Blue line: UK whole population relationship between PM2.5 and deprivation • Being exposed to higher pollution isn’t simply a function of being deprived • Can decarbonisation reduce some of these inequalities? Evaluating disparities in air pollution as a function of ethnicity, deprivation and sectoral emissions in England. Gray, N.R., Lewis, A.C. & Moller, S.J., Environment International. 194, 109146, 2024.
7. o Historically a major contributor to urban air pollution Road transport decarbonisation impacts o Changing rapidly, and now much lower tailpipe emissions Road transport changes o Steep reductions in tailpipe emissions over last decade o Friction-related emissions remain with BEVs / Fuel cells o Euro6 vehicles much cleaner than Euro5 o Growing BEV fleet eliminates NOx emissions o Deprivation-based disparities are reducing due to decarbonisation o But no perfect solutions – non-exhaust PM may increase slightly
8. The equity of subsidy? Wealthier people are subsidised to drive new electric cars….. Those cars get driven past poorer communities, so they get an air quality benefit…. Over time those cars trickle down to second and third hand owners…..
9. Decarbonising domestic heating • ~20% UK CO2 emissions from home heating • In many UK cities burning fossil gas is now a larger source of NOx pollution than road vehicles. • Heat pumps should be another win-win? Fractions of CO2 and NOx emissions from heat and power / road transport in central London Evidence of Heating-Dominated Urban NOx Emissions. Cliff, S.J., Drysdale, W., Lewis, A.C., Møller, S.J., Helfter, C., Metzger, S., Liddard, R., Nemitz, E., Barlow, J.F. & Lee, J.D., 28 Feb 2025, In: Environmental Science and Technology. 59, 9, 10 p., 4399–4408.
11. Where are the heat pumps (and grants) going? • DESNZ data on heat pump installations is reported at the parliamentary constituency level. • Wide variation in heat pump adoption across UK constituencies
12. Criteria for installation including untargeted grants have skewed installations towards more affluent rural / suburban areas, often places with pre-existing good air quality. There is no ‘trickle down’ of older heat pumps to poorer areas. Benefits stay local to the installation. In this example net zero grants don’t generate equitable air quality co-benefits. St Ives constituency recorded the highest uptake of heat pump subsidies under the scheme, with 467 installations (up to May 2025)—equivalent to 52.4 per 10,000 people. In contrast, Liverpool Riverside saw between 1 and 4 installations
13. Accumulated advantage / disadvantage If the UK meets net zero in 2025, ultimately everyone will have a heat pump. Under current trajectories, the least polluted locations see NOx reductions early, most polluted locations last of all. This can be addressed partly through targeting installations based on building suitability and fewer untargeted subsidies
14. Some net zero actions bring limited AQ co-benefits • By ~2027 – more NOx from UK aviation landing/take-offs than all HDVs combined. • The use of a sustainable fuel may support net zero but it doesn’t deliver public health benefits via better air quality or reduced noise. Aircraft LTO is a major ground level source of NOx relative to other emissions. (NAEI 2024)
15. Summary • Many reasons for optimism – dramatic reductions in emissions of some pollutants in recent years. • Considerable overlap between climate gases and air pollution sources • Net zero isn’t ‘place-specific’ but air pollution and public health is. • Deprived and minoritized communities are more exposed to pollution • Improving air quality when decarbonising is a direct and immediate public benefit, sometimes undersold. • Decarbonisation has already helped reduce (but not eliminate) disparities associated with traffic pollution. • Other decarbonisation actions and policies may not always deliver cobenefits where they are most needed. • Co-benefits assessment and systems-level analysis of decarbonisation investments may increase value for money and public buy-in.