Enhancing Air Quality Forecasts with AP4 Model Updates

The U.S. Environmental Justice 40 Initiative is driving the need for more accurate community-level models.The Air Pollutant Emissions Experiments and Policy Version 4 (AP4) model, a key tool for Environmental Justice initiatives, was recently upgraded to better simulate particulate matter (PM) air pollutant impacts at county and census tract levels across the contiguous U.S [1].By expanding the AP4 model to include industrial point-source emissions, more accurate forecasts of emissions can be provided to policymakers, ultimately informing data-driven decisions that prioritize public health, environmental stewardship, and social equity. II. Model OverviewAP4 is a reduced-form model, written in MATLAB, that generates source-receptor (S-R) matrices for analyzing marginal damages caused by one-ton increments of emissions above a baseline and built using publicly available data from 10,000 individual sources and county source locations [2].AP4 consists of four main components (Fig 1.): 1.National Emission Inventory (NEI): Provides emissions data (tons per year).2. Air Quality Modeling: Calculates county-level marginal concentrations of PM from additional emissions.3. Health Effects Modeling: Uses dose-response curves to estimate added health risks.4. Impacts Modeling: Quantifies mortality and monetized damages associated with marginal health impacts.