The Chemical and Socio-Spatial Frontier: Causal Modeling of Non-Exhaust and Industrial PM2.5 Speciation and Longitudinal Equity in the Post- Mitigation ULEZ Environment

Abstract Background: London’s Ultra Low Emission Zone (ULEZ) has lessened exhaust discharges, refining air quality, and health outcomes like children’s lung function. However, latest expansions reveal a plateau, with PM2.5 levels exceeding WHO recommendations due to non-exhaust (brake/tire wear) and industrial sources. The scrappage scheme’s closure in September 2024 exacerbates financial burdens on low-income, car owner groups, raising equity concerns. Objectives: This study aims to quantify spatial exposure to speciated PM2.5 pollutants (Industrial: V, Ni, As, non-exhaust: Fe, Cu, Zn) across deprivation deciles, establish causal links to respiratory health and anxiety, and assess post-mitigation residual stress and social isolation in vulnerable populations. Methods: Employing a quasi-experimental Difference-in-Difference design, incorporate LAQN/Defra speciation data with GIS (GWR) for mapping and Positive Matrix factorization for source apportionment. Link to CHILL/NHS health data via mixed-effects regression. Qualitative semi-structured interviews (n=30-40) with Outer London occupants denote recognition justice. Expected Outcome: Findings will inform targeted policies on industrial areas and non-exhaust controls, advocating perpetual equity support. Key words: ULEZ, PM2.5Speciation, non-exhaust emissions, industrial pollution, environmental justice, socio-spatial equity, source apportionment, Difference-in-Difference, recognition justice.