4.3 Sources of Data and selection heirarchy

EPA calculated the onroad emissions for 2023 for all states using the most recent version of MOVES, MOVES5.0.0, with a copy of the default database movesdb20241112 renamed to movesdb20241112_nonoxadj to signify that engine-out NOX adjustments based on ambient humidity were turned off. In the NEI and modeling platform process, the MOVES humidity-based adjustments to nitrogen oxide species (NO, NO2, HONO, and NOX) are applied inside the Sparse Matrix Operator Kernel Emissions (SMOKE) at the grid cell level using gridded meteorology, instead of MOVES applying adjustments at runtime. The sources of MOVES input data for the NEI vary by area, representing a mix of local data, EPA defaults, and some MOVES defaults. The S/L/T agencies that submitted data for 2023 are listed below in Section 4.8. EPA used programs within the SMOKE modeling system that use data output from MOVES to generate the emission inventories in all 50 states for each hour of the year. These emissions are summed over all hours and across road types to develop the emissions for the NEI. For the state of California, EPA used onroad emissions provided by California based on the EMFAC model. Pollutants submitted by California were retained to the extent possible, while any missing pollutants were estimated using a combination of data from MOVES and CARB.

The data selection hierarchy for 2023 favored local input data over EPA-developed information. For areas that did not submit a MOVES CDB for this NEI, EPA used a 2023 CDB containing EPA defaults (e.g., SPGM registration data and StreetLight telematics data) and some MOVES defaults, as described in Section 4.6.4. The selection definition for the onroad category in EIS is shown in Table 4.7.

Table 4.7: Onroad Data Category Selection Hierarchy for 2023 NEI

Priority	Dataset	Notes
1	S/L/T-supplied emissions	Nez Perce TribeCalifornia submitted emissions calculated with their own model (EMFAC).
2	S/L/T-supplied input data through 2023 NEI process
3	2023EPA_ONROAD	All data from EPA Default or MOVES5