The air quality, health and economic costs and benefits of a zero carbon UK: a comprehensive synopsis

Background Net Zero policies rarely consider air quality and physical activity health cobenefits, cost–benefit analysis, exposure indoors and exposure inequalities. Objectives To calculate the air quality, health and economic costs and benefits of United Kingdom Net Zero policy, impacts on inequalities and consult the public on the acceptance of Net Zero policy. Design and methods We used sophisticated emissions and air quality models, Life Table health impact analysis, United Kingdom Government cost–benefit methods and estimated exposure inequalities. We compared 2030 and 2040 United Kingdom PM 10 , PM 2.5 , nitrogen dioxide and ozone predictions using existing air quality policy, or Business as Usual, with Net Zero policy. We predicted Net Zero 2050 pollutant concentrations. Interventions Business as Usual scenarios were from United Kingdom Government projections and Net Zero scenarios were from the Climate Change Committee’s sixth Carbon Budget. We used the Balanced Net Zero and Widespread Innovation Pathways for road transport, building heating and active travel. Main outcome measures United Kingdom air pollution, including exposure inequalities, mortality, morbidity and economic costs and benefits. Results Air quality: Under Business as Usual, nitrogen dioxide and particulate matter reduced by 2030 due to new vehicles. The 2040 Balanced Net Zero Pathway and Widespread Innovation scenarios showed further reductions, driven by electric vehicle uptake, reduced vehicle kilometre travelled compared with Business as Usual, and low-carbon building heating. Particulate matter reductions from buildings was two and three times greater than from road transport, for Widespread Innovation and Balanced Net Zero Pathways, respectively. Balanced Net Zero Pathway+ 2050 predictions showed additional air pollution benefits. Exposure inequalities analysis: In 2019, urban central professionals experienced 14 µg m −3 higher nitrogen dioxide concentrations than rural elderly . At 1.5 µg m −3 , PM 2.5 concentrations varied less across geodemographic groups. Despite future improvements in nitrogen dioxide, inequalities persisted, but were less pronounced, due in part to Net Zero policies. Indoor air pollution: Removing gas cooking at home for Net Zero may result in greater nitrogen dioxide reductions than changes in outdoor air pollution. Health and active travel impacts: Compared with Business as Usual, Balanced Net Zero Pathway gave 4.9 (95% confidence interval 1.0 to 9.0) million life-years gained across the United Kingdom, to 2154, including 1.1 (95% confidence interval 0.7 to 1.6) million life-years gained from active travel. Avoided chronic obstructive pulmonary disease and childhood asthma cases were 201,000 (95% confidence interval 150,000 to 250,000) and 192,000 (95% confidence interval 64,600 to 311,000). Monetised morbidity benefits of £52.1B (95% confidence interval 36.4 to 67.8) added significantly to mortality benefits of £77.9B (95% confidence interval 42.9 to 90.8). Total yearly air pollution and active travel benefits were £153B (95% confidence interval 122 to 184), rising to £278B (95% confidence interval 228 to 334), including outcomes with weaker evidence. Costs/benefits: Building sector Balanced Net Zero Pathway air quality health benefits were £21.3B (95% confidence interval 16.4 to 26.2) by 2050 and were £98.4B (95% confidence interval 75.7 to 121.1) by 2154. Transport benefits were £9.1B (95% confidence interval 7.0 to 11.2) by 2050 and were £36.5B (95% confidence interval 28.1 to 44.9) by 2154. Balanced Net Zero Pathway building sector operating costs alone did not achieve break-even, but with greenhouse gases reductions (lower benefits) break-even was achieved by 2052. Air pollution health benefits reduced the building sector time to break-even by between 3.1 (95% confidence interval 2.5 to 4.7) and 6.3 (95% confidence interval 4.7 to 7.6) years. Public engagement: Conversations reflected an intergenerational commitment to Net Zero policies, although there was uncertainty about an individual’s impact. Limitations Uncertainties in future air quality and meteorological conditions; through lack of evidence, being unable to use multipollutant models and indoor air pollution, missing indoor health and monetised benefits; some health outcomes with weaker health evidence strongly influenced the results. The COVID pandemic prevented us from exploring social acceptance as planned. Conclusions This study identified health and economic cobenefits through reductions in greenhouse gases, air pollution, inequalities and increased exercise. Future work To separately evaluate the health and monetary impacts of indoor and outdoor air pollution; to understand the overlapping effects of PM 2.5 and nitrogen dioxide health impacts; to develop effective ways of communicating the health and economic benefits and to increase the social acceptability of Net Zero. Funding This synopsis presents independent research funded by the National Institute for Health and Care Research (NIHR) Public Health Research programme as award number NIHR129406.