High-Resolution Assessment of Air Quality, Health, and Equity Co-Benefits of California’s 2022 Scoping Plan for Carbon Neutrality in the South Coast Air Basin

The California Air Resources Board's 2022 Scoping Plan (SP) outlines California's pathway to achieve carbon neutrality by 2045, targeting deep reductions in greenhouse gas and criteria air pollutant emissions. Understanding the regional implications of this statewide plan is critical for combating environmental inequalities. In this study, we evaluate air quality, health, and equity cobenefits of the 2022 SP in the South Coast Air Basin (SoCAB), using a high-resolution (1 km × 1 km) chemical transport model. Achieving carbon neutrality could reduce annual basin-wide PM_2.5 by 1.72 μg/m³ in 2035 and 3.46 μg/m³ in 2045 under the SP scenario relative to the reference scenario, avoiding approximately 5211 and 12,222 premature deaths among 16.8 million residents. The monetary health benefits are US$49.5 and US$116.2 billion, which exceed the costs estimated within the SP for GHG abatement. While the SP benefits disadvantaged communities─with 41.4% of gains accruing to 42.0% SoCAB residents, several heavily impacted communities adjacent to the Ports of Long Beach still experience higher PM_2.5 exposure relative to basin-average levels under SP. Overall, we highlight the considerable benefits of deep decarbonization in reducing ambient PM_2.5 levels and safeguarding human health while also demonstrating the need for source-oriented emission regulations for disadvantaged communities.