Air quality and health co-benefits of bus electrification: evidence from a UK metropolitan area

Air pollution in cities is a critical environmental and public health concern, where achieving legal limit values and progress towards WHO health-based guidelines may be challenging. Transportation is one of the leading causes of air pollution in urban areas, and hence public transportation systems such as low / zero tailpipe emission buses play a crucial role in reducing toxic emissions to air, and improving sustainable mobility and social connectivity. In addition, as combustion emissions from transport also negatively impact the climate, a move to transportation systems that can be powered using green energy are necessary. Responding to the climate severity and its link to urban air pollution, a global push for sustainable transportation is occurring. This study employed an advanced street scale air quality dispersion modelling system to assess the impact of five hypothetical bus fleet electrification scenarios (i.e. 20 %, 40 %, 60 %, 80 % and 100 % electrification) on the changes to air pollution levels in a UK metropolitan area (West Midlands). Modelled spatial distributions of air pollutant concentrations have been integrated into the West Midlands Air Quality Lifecourse Assessment tool for the assessment of associated air quality related health effects, generating electoral ward level health and economic outcomes. Potential air quality improvements were observed in nitrogen dioxide (NO₂) concentration up to 13 μg m^-3 (or 27 %), and in PM_2.5 (particulate matter with diameter less than 2.5 μm) concentration up to 0.5 μg m^-3 (or 4 %). The modest improvements in regional health considering only air quality related impacts on disease incidence (up to 3.1 % in at attributable burden of asthma diagnoses over 10 years) and mortality (up to 0.7 % in deaths prevented over 10 years) were also observed. This study provides evidence for the air quality and health co-benefits of the carbon transportation systems.