To assess exposure to near-roadway hotspots and evaluate exposure equity, we first estimate the emission density for PM2.5 and NOX at the census block level, stratified by vehicle type (LDV, MDV, and HDV). This approach builds upon and refines the traffic density methodologies used in our previous studies . Emission factors are derived from the EPA's Motor Vehicle Emission Simulator (MOVES), while vehicle activity data is obtained from the Federal Highway Administration's (FHWA) Highway Performance Monitoring System (HPMS).