Publication Detail

Modeling Expected Air Quality Impacts of Oregon's Proposed Expanded Clean Fuels Program


Journal Article

Policy Institute for Energy, Environment, and the Economy

Suggested Citation:
Li, Yiting, Guihua Wang, Colin Murphy, Michael J. Kleeman (2023) Modeling Expected Air Quality Impacts of Oregon's Proposed Expanded Clean Fuels Program. Atmospheric Environment 296

The public health burden of traffic-related air pollution falls most heavily on the population living closest to major transportation corridors, which leads to exposure disparities between different socio-economic groups across the United States. The state of Oregon has adopted climate policies to reduce transportation fuel carbon intensity (CI). These climate policies have the potential co-benefit of reducing air pollution exposure disparities for different socio-economic groups. Here we analyze the emissions and air quality outcomes of three future year (2035) scenarios for transportation fuels in Oregon: (i) a Business as usual (BAU) scenario, (ii) a Clean Fuels Program (CFP) scenario that represents adoption and successful achievement of a proposed 25% reduction in carbon intensity in 2035; and (iii) a maximum ambition scenario (CFP MAX) that builds on the CFP scenario to achieve a 37% CI reduction by adopting low carbon fuels more aggressively, especially for heavy duty vehicles. Transportation emissions under all scenarios were estimated using the MOVES model for every county in Oregon. Detailed emissions with 4 km spatial resolution were then developed for each scenario by scaling the National Emissions Inventory (NEI) for the year 2017 based on the emissions derived from the MOVES analysis. Air quality in 2035 was simulated using the UCD/CIT chemical transport model that enables a detailed analysis of PM2.5 and PM0.1 components and sources. Exposure fields were analyzed using the BenMAP model to predict public health outcomes. Environmental justice analysis was conducted by race/ethnicity categories and income categories obtained from the American Community Survey (ACS). Results suggest that adoption of low-carbon transportation fuels will improve air quality in Oregon, yielding public health benefits equivalent to approximately $80M/yr. Adoption of low carbon transportation fuels will also reduce disparities in exposure to transportation-related air pollution between residents in different race/ethnicity categories by ∼14% in Portland and ∼20% in Salem. Adoption of low-carbon fuels reduces PM2.5 mass disparity by 10% in Salem, but does not have a significant effect in Portland, because on-road mobile sources contribute to less than 3% of the total PM2.5 mass disparity in this city. The analysis reveals that the spatial distribution of each race/ethnicity group in each city is the primary factor that determines the impact of low carbon fuel adoption on exposure disparity.

Key words: GHG reductions, PM2.5, PM0.1, Environmental justice, MOVES, BenMAP