9.17 On-Road Motor Vehicles
Multiple Categories (list of categories attached in the end of chapter)
9.17.1 Introduction
On-road motor vehicles emissions account for a large portion of SFBA’s total emissions with a mix of major criteria, toxic and greenhouse gas (GHG) pollutants. In 2015, there were nearly 4.4 million on-road motor vehicles in the San Francisco Bay Area (SFBA), traveling an estimated daily average of 162 million miles. With close proximity of roads to urban populations and near-surface release height of vehicle tailpipes, the on-road vehicle emissions sector has historically been and still remains a major health risk to SFBA residents. Accurate estimation of the emission trends from motor vehicles is an essential element of controlling air pollution and improving air quality. The emissions reflected herein include all five criteria pollutants (PM, VOC, NOx, SOx, CO) as well as organic compounds (reactive and total).
9.17.2 Methodology
To estimate emissions from a large fleet of vehicles, many variables are required to be documented and quantified. The most important among them is the rate at which a vehicle produces various pollutants. This is referred to as vehicle emission factor; this variable varies with emission processes (such as traveling on road or idling), vehicle and fuel types, emission control technologies, vehicle age, and operating conditions (such as speed, ambient temperature). Another important variable is called the fleet activity. This term relates to the number of in-use vehicles, number of trips made, and the vehicle miles traveled (VMT).
In the current base year emissions inventory (EI), there are 288 on-road mobile source categories designated for estimating emissions from the entire fleet of on-road motor vehicles traveling on public roads in the SFBA (see attachment in the end of chapter).
Due to the complexity in the on-road mobile emissions estimation process, the District has developed a current base year EI for this sector, primarily based on the EMission FACtors (EMFAC) model developed by California Air Resources Board (CARB) which calculate emission factors, state and regional emissions in California420. The EMFAC model has undergone many improvements and refinements and the latest version EMFAC2017 (Version 1.1.2) at the time of base year emission inventory development has been used for the current base year inventory421. EMFAC2017 provides emission estimates for year 2000 to 2050. Emissions output from EMFAC2011, which was the previously the most recent version of EMFAC, was accessed from the District’s archive and used to estimate historical emissions (1990 to 1999).
For a full description of the model and the methodology, version history, underlying data, and further supporting documentation, reference should be made to CARB Website1. The remaining section summarizes the procedures on developing the current base year EI using the EMFAC model.
An EMFAC2017 model run in Emissions mode was conducted using the model’s default inputs specific to each county to generate annual average daily criteria pollutant emissions by process, vehicle class, fuel type and control technology (e.g., catalytic, non-catalytic) for each year from 2000 to 2040.
The output emissions were combined with EMFAC off-model adjustment factors for gasoline Light Duty Vehicle (LDV) to account for estimated emission impacts from Safer Affordable Fuel-Efficient (SAFE) Vehicles Rules and actions adopted by the U.S. Environmental Protection Agency (U.S. EPA) and the National Highway Traffic Safety Administration (NHTSA) in late 2019 and early 2020422.
The resulting emissions were assigned with District’s category number based on emission process, vehicle class, fuel type and control technology.
The annual average daily criteria emissions of historical years (1990-1999) modeled by EMFAC2011 were retrieved from the District archive. The EMFAC2011 emissions are by process, vehicle class and fuel type, but not control technology. In order to assign a valid category number, the District further disaggregated the emissions by control technology using a split factor specific to its process, vehicle class and fuel type which are derived from the EMFAC2017 emissions of the year closest to 1999.
The disaggregated EMFAC2011 emissions were then assigned with District’s appropriate category number based on emission process, vehicle class, fuel type and control technology.
EMFAC2011 doesn’t model all pollutants (e.g., TSP, HC, N2O) due to the design limitation. Therefore, the District augmented emissions of additional pollutants by scaling from emissions of existing pollutants using pollutant scaling factors, such as ratio of TSP to PM10, HC to TOG, and N2O to NOx. The pollutant scaling factors were category specific and derived from EMFAC2017 emissions of the year closest to 1999.
The annual average daily EMFAC2017 and EMFAC2011 emissions were then annualized by multiplying with the number of operation days per year specific to each vehicle class and combined to cover all years from 1990 to 2040.
9.17.3 Changes in Methodology
Compared to previous base year, the following updates have been made in the current base year inventory:
- EMFAC2017 was used to estimate emissions for years 2000 to 2040 instead of EMFAC2011.
- Average daily emissions from EMFAC were multiplied by the number of vehicle-class specific operation days per year instead of 365 days to estimate annual emissions.
- Adjustment factors estimated by CARB were applied to light-duty vehicles to account for the emission impact from USEPA’s SAFE rule.
9.17.4 Emissions
On-road motor vehicles used to be the largest contributor to NOx, CO and TOG emissions. With continuous regulatory efforts as well as new technologies in engine manufacturing, control devices and clean fuel, its emissions have been significantly reduced. However, it’s still a major source of NOx and PM2.5. A summary of emissions by category, county, and year are available via the associated data dashboard for this inventory publication.
9.17.5 Trends
(a) Historical Emissions / History
Previous versions of EMFAC model and historical DMV registration data are the primary data source for estimating historical emissions. For more details, please refer to EMFAC technical documentation1.
(b) Future Projections / Growth
EMFAC model uses socio-econometric regression model forecasting methods to predict new vehicle sales and VMT growth trends. These models connect the activity estimates of EMFAC to state and national economic indicators, fuel prices, regional human populations, and regional vehicle ownership characteristics. For more details, please refer to EMFAC technical documentation1.
(c) Controls
The EMFAC model has accounted for emissions benefits of all on-road mobile source “On-the-Book” regulations (adopted by the time when the EMFAC model was developed). EMFAC2017 reflects state and federal laws, regulations, and legislative actions that were adopted as of December 2017, which aimed at lowering fleet average emission factors of both criteria and GHG pollutants.
The following are some types of controls for motor vehicle emissions:
Emission Standards. Since 1972, introduction of more stringent emission standards has caused the entire motor vehicle fleet to become cleaner as newer vehicle replace the old ones. The introduction of California’s Low Emissions Vehicles Program in 1994 ensured that this trend has continued into the present century. More recent regulations include CARB’s Truck and Bus Regulation aiming to reduce toxic emissions from heavy-duty diesel trucks and buses, and California’s Advanced Clean Cars (ACC) Program which mandated requirements for the incorporation of greater numbers of zero-emission vehicles.
Clean Fuels Program. This program includes Re-Formulated Gasoline Phase I (started January 1990), the Winter-time Oxygenated Fuels Program (introduced in November 1992) and Reformulated Gasoline Phase II (beginning January 1996). To reduce sulfur oxides (SOx) emissions, CARB has also regulated the sulfur content in both gasoline and diesel fuels. The latest regulations beginning 1997, reduced sulfur content of diesel fuel to 15 part per million.
Inspection and Maintenance program (I/M). Also known as the Smog Check, this program was introduced in 1984. Enhancements to the original I/M were introduced in 1990, with further improvements phased in beginning of year 1994. In October 2003, ARB started implementing the Enhanced I/M Program (Smog Check II) in the Bay Area. As a result, further ROG, but more importantly NOx, emission reductions were achieved. More changes were made to the program mandated by State law beginning January 1, 2013.
Benefits from these controls are included in the emissions estimates. For a full list of regulations and policies EMFAC model incorporated, please refer to EMFAC technical documentation1.
In addition, there are controls to reduce motor vehicle use and congestion. These are generally referred to as Transportation Control Measures. Examples of these are programs that increase transit usage and signal timing projects. The benefits from some of these measures are included as part of the travel data (less VMT, less congested speed, etc.), and hence, already included in the emissions estimates from the relevant version of the emissions model.
9.17.6 Uncertainties
As the primary data source for these categories, the EMFAC model itself is a state-of-science and robust model. The model is based on the most up-to-date emission factors from dynamometer tests and field studies, incorporates fleet activity estimated from vehicle registration or collected from local transportation authorities, and reflects all regulations and special programs at national and state level. The model has gone through updates and improvements over time with increasing understanding of emissions from on-road mobile sources. Higher uncertainties reside in historical emissions estimated by older version of EMFAC.
9.17.7 Attachment: On-Road Motor Vehicle Categories Covered in the Chapter
| Category # | Description | Classification |
|---|---|---|
| 712 | Light Duty Passenger Gasoline Exhaust Cold Start Catalytic | Mobile |
| 713 | Light Duty Passenger Gasoline Exhaust Cold Start Non-Catalytic | Mobile |
| 724 | Light Duty Passenger Gasoline Exhaust Stabilized Catalytic | Mobile |
| 725 | Light Duty Passenger Gasoline Exhaust Stabilized Non-Catalytic | Mobile |
| 726 | Light Duty Passenger Diesel Exhaust Stabilized Diesel | Mobile |
| 730 | Light Duty Passenger Gasoline Running Evaporation Evaporative Catalytic | Mobile |
| 731 | Light Duty Passenger Gasoline Running Evaporation Evaporative Non-Catalytic | Mobile |
| 732 | Light Duty Passenger Gasoline Diurnal Breathing Evaporative Catalytic | Mobile |
| 733 | Light Duty Passenger Gasoline Diurnal Breathing Evaporative Non-Catalytic | Mobile |
| 735 | Light Duty Passenger Gasoline Hot Soak Evaporation Evaporative Catalytic | Mobile |
| 736 | Light Duty Passenger Gasoline Hot Soak Evaporation Evaporative Non-Catalytic | Mobile |
| 737 | Light Duty Passenger Gasoline Tire Wear Wear Catalytic | Mobile |
| 738 | Light Duty Passenger Gasoline Tire Wear Wear Non-Catalytic | Mobile |
| 739 | Light Duty Passenger Diesel Tire Wear Wear Diesel | Mobile |
| 833 | Light Heavy Duty Trucks (I) Gasoline Exhaust Stabilized Catalytic | Mobile |
| 834 | Light Heavy Duty Trucks (I) Gasoline Exhaust Stabilized Non-Catalytic | Mobile |
| 835 | Light Heavy Duty Trucks (I) Diesel Exhaust Stabilized Diesel | Mobile |
| 839 | Light Heavy Duty Trucks (I) Gasoline Running Evaporation Evaporative Catalytic | Mobile |
| 840 | Light Heavy Duty Trucks (I) Gasoline Running Evaporation Evaporative Non-Catalytic | Mobile |
| 841 | Light Heavy Duty Trucks (I) Gasoline Diurnal Breathing Evaporative Catalytic | Mobile |
| 842 | Light Heavy Duty Trucks (I) Gasoline Diurnal Breathing Evaporative Non-Catalytic | Mobile |
| 844 | Light Heavy Duty Trucks (I) Gasoline Hot Soak Evaporation Evaporative Catalytic | Mobile |
| 845 | Light Heavy Duty Trucks (I) Gasoline Hot Soak Evaporation Evaporative Non-Catalytic | Mobile |
| 846 | Light Heavy Duty Trucks (I) Gasoline Tire Wear Wear Catalytic | Mobile |
| 847 | Light Heavy Duty Trucks (I) Gasoline Tire Wear Wear Non-Catalytic | Mobile |
| 848 | Light Heavy Duty Trucks (I) Diesel Tire Wear Wear Diesel | Mobile |
| 852 | Urban Buses Diesel Exhaust Stabilized Diesel | Mobile |
| 856 | Urban Buses Diesel Tire Wear Wear Diesel | Mobile |
| 860 | Motorcycles Gasoline Exhaust Cold Start Non-Catalytic | Mobile |
| 862 | Motorcycles Gasoline Exhaust Stabilized Non-Catalytic | Mobile |
| 863 | Motorcycles Gasoline Running Evaporation Evaporative Non-Catalytic | Mobile |
| 864 | Motorcycles Gasoline Diurnal Breathing Evaporative Non-Catalytic | Mobile |
| 866 | Motorcycles Gasoline Hot Soak Evaporation Evaporative Non-Catalytic | Mobile |
| 867 | Motorcycles Gasoline Tire Wear Wear Non-Catalytic | Mobile |
| 971 | Light Duty Passenger Gasoline Resting Losses Evaporative Non-Catalytic | Mobile |
| 972 | Light Duty Passenger Gasoline Resting Losses Evaporative Catalytic | Mobile |
| 973 | Light Duty Trucks (I) Gasoline Exhaust Stabilized Non-Catalytic | Mobile |
| 974 | Light Duty Trucks (I) Gasoline Exhaust Cold Start Non-Catalytic | Mobile |
| 976 | Light Duty Trucks (I) Gasoline Diurnal Breathing Evaporative Non-Catalytic | Mobile |
| 977 | Light Duty Trucks (I) Gasoline Hot Soak Evaporation Evaporative Non-Catalytic | Mobile |
| 978 | Light Duty Trucks (I) Gasoline Running Evaporation Evaporative Non-Catalytic | Mobile |
| 979 | Light Duty Trucks (I) Gasoline Resting Losses Evaporative Non-Catalytic | Mobile |
| 980 | Light Duty Trucks (I) Gasoline Tire Wear Wear Non-Catalytic | Mobile |
| 981 | Light Duty Trucks (I) Gasoline Exhaust Stabilized Catalytic | Mobile |
| 982 | Light Duty Trucks (I) Gasoline Exhaust Cold Start Catalytic | Mobile |
| 984 | Light Duty Trucks (I) Gasoline Diurnal Breathing Evaporative Catalytic | Mobile |
| 985 | Light Duty Trucks (I) Gasoline Hot Soak Evaporation Evaporative Catalytic | Mobile |
| 986 | Light Duty Trucks (I) Gasoline Running Evaporation Evaporative Catalytic | Mobile |
| 987 | Light Duty Trucks (I) Gasoline Resting Losses Evaporative Catalytic | Mobile |
| 988 | Light Duty Trucks (I) Gasoline Tire Wear Wear Catalytic | Mobile |
| 989 | Light Duty Trucks (I) Diesel Exhaust Stabilized Diesel | Mobile |
| 992 | Light Duty Trucks (I) Diesel Tire Wear Wear Diesel | Mobile |
| 993 | Medium Duty Trucks Gasoline Exhaust Stabilized Non-Catalytic | Mobile |
| 994 | Medium Duty Trucks Gasoline Exhaust Cold Start Non-Catalytic | Mobile |
| 996 | Medium Duty Trucks Gasoline Diurnal Breathing Evaporative Non-Catalytic | Mobile |
| 997 | Medium Duty Trucks Gasoline Hot Soak Evaporation Evaporative Non-Catalytic | Mobile |
| 998 | Medium Duty Trucks Gasoline Running Evaporation Evaporative Non-Catalytic | Mobile |
| 999 | Medium Duty Trucks Gasoline Resting Losses Evaporative Non-Catalytic | Mobile |
| 1000 | Medium Duty Trucks Gasoline Tire Wear Wear Non-Catalytic | Mobile |
| 1001 | Medium Duty Trucks Gasoline Exhaust Stabilized Catalytic | Mobile |
| 1002 | Medium Duty Trucks Gasoline Exhaust Cold Start Catalytic | Mobile |
| 1004 | Medium Duty Trucks Gasoline Diurnal Breathing Evaporative Catalytic | Mobile |
| 1005 | Medium Duty Trucks Gasoline Hot Soak Evaporation Evaporative Catalytic | Mobile |
| 1006 | Medium Duty Trucks Gasoline Running Evaporation Evaporative Catalytic | Mobile |
| 1007 | Medium Duty Trucks Gasoline Resting Losses Evaporative Catalytic | Mobile |
| 1008 | Medium Duty Trucks Gasoline Tire Wear Wear Catalytic | Mobile |
| 1009 | Motorcycles Gasoline Resting Losses Evaporative Non-Catalytic | Mobile |
| 1159 | Light Duty Passenger Gasoline Brake Wear Wear Catalytic | Mobile |
| 1160 | Light Duty Passenger Gasoline Brake Wear Wear Non-Catalytic | Mobile |
| 1161 | Light Duty Passenger Diesel Brake Wear Wear Diesel | Mobile |
| 1162 | Light Duty Trucks (I) Gasoline Brake Wear Wear Catalytic | Mobile |
| 1163 | Light Duty Trucks (I) Gasoline Brake Wear Wear Non-Catalytic | Mobile |
| 1164 | Light Duty Trucks (I) Diesel Brake Wear Wear Diesel | Mobile |
| 1165 | Medium Duty Trucks Gasoline Brake Wear Wear Catalytic | Mobile |
| 1166 | Medium Duty Trucks Gasoline Brake Wear Wear Non-Catalytic | Mobile |
| 1167 | Light Heavy Duty Trucks (I) Gasoline Brake Wear Wear Catalytic | Mobile |
| 1168 | Light Heavy Duty Trucks (I) Gasoline Brake Wear Wear Non-Catalytic | Mobile |
| 1169 | Light Heavy Duty Trucks (I) Diesel Brake Wear Wear Diesel | Mobile |
| 1170 | Medium Heavy Duty Trucks Gasoline Exhaust Stabilized Catalytic | Mobile |
| 1171 | Medium Heavy Duty Trucks Gasoline Exhaust Stabilized Non-Catalytic | Mobile |
| 1172 | Medium Heavy Duty Trucks Diesel Exhaust Stabilized Diesel | Mobile |
| 1173 | Medium Heavy Duty Trucks Gasoline Running Evaporation Evaporative Catalytic | Mobile |
| 1174 | Medium Heavy Duty Trucks Gasoline Running Evaporation Evaporative Non-Catalytic | Mobile |
| 1175 | Medium Heavy Duty Trucks Gasoline Diurnal Breathing Evaporative Catalytic | Mobile |
| 1176 | Medium Heavy Duty Trucks Gasoline Diurnal Breathing Evaporative Non-Catalytic | Mobile |
| 1177 | Medium Heavy Duty Trucks Gasoline Hot Soak Evaporation Evaporative Catalytic | Mobile |
| 1178 | Medium Heavy Duty Trucks Gasoline Hot Soak Evaporation Evaporative Non-Catalytic | Mobile |
| 1179 | Medium Heavy Duty Trucks Gasoline Tire Wear Wear Catalytic | Mobile |
| 1180 | Medium Heavy Duty Trucks Gasoline Tire Wear Wear Non-Catalytic | Mobile |
| 1181 | Medium Heavy Duty Trucks Diesel Tire Wear Wear Diesel | Mobile |
| 1182 | Medium Heavy Duty Trucks Gasoline Brake Wear Wear Catalytic | Mobile |
| 1183 | Medium Heavy Duty Trucks Gasoline Brake Wear Wear Non-Catalytic | Mobile |
| 1184 | Medium Heavy Duty Trucks Diesel Brake Wear Wear Diesel | Mobile |
| 1185 | Urban Buses Diesel Brake Wear Wear Diesel | Mobile |
| 1186 | Heavy Heavy Duty Trucks Diesel Exhaust Stabilized Diesel | Mobile |
| 1187 | Heavy Heavy Duty Trucks Diesel Tire Wear Wear Diesel | Mobile |
| 1188 | Heavy Heavy Duty Trucks Diesel Brake Wear Wear Diesel | Mobile |
| 1189 | Motorcycles Gasoline Brake Wear Wear Non-Catalytic | Mobile |
| 1295 | Light Duty Trucks (II) Gasoline Exhaust Stabilized Non-Catalytic | Mobile |
| 1296 | Light Duty Trucks (II) Gasoline Exhaust Cold Start Non-Catalytic | Mobile |
| 1297 | Light Duty Trucks (II) Gasoline Hot Soak Evaporation Evaporative Non-Catalytic | Mobile |
| 1298 | Light Duty Trucks (II) Gasoline Running Evaporation Evaporative Non-Catalytic | Mobile |
| 1299 | Light Duty Trucks (II) Gasoline Resting Losses Evaporative Non-Catalytic | Mobile |
| 1300 | Light Duty Trucks (II) Gasoline Diurnal Breathing Evaporative Non-Catalytic | Mobile |
| 1301 | Light Duty Trucks (II) Gasoline Tire Wear Wear Non-Catalytic | Mobile |
| 1302 | Light Duty Trucks (II) Gasoline Brake Wear Wear Non-Catalytic | Mobile |
| 1303 | Light Duty Trucks (II) Gasoline Exhaust Stabilized Catalytic | Mobile |
| 1304 | Light Duty Trucks (II) Gasoline Exhaust Cold Start Catalytic | Mobile |
| 1305 | Light Duty Trucks (II) Gasoline Hot Soak Evaporation Evaporative Catalytic | Mobile |
| 1306 | Light Duty Trucks (II) Gasoline Running Evaporation Evaporative Catalytic | Mobile |
| 1307 | Light Duty Trucks (II) Gasoline Resting Losses Evaporative Catalytic | Mobile |
| 1308 | Light Duty Trucks (II) Gasoline Diurnal Breathing Evaporative Catalytic | Mobile |
| 1309 | Light Duty Trucks (II) Gasoline Tire Wear Wear Catalytic | Mobile |
| 1310 | Light Duty Trucks (II) Gasoline Brake Wear Wear Catalytic | Mobile |
| 1311 | Light Duty Trucks (II) Diesel Exhaust Stabilized Diesel | Mobile |
| 1312 | Light Duty Trucks (II) Diesel Tire Wear Wear Diesel | Mobile |
| 1313 | Light Duty Trucks (II) Diesel Brake Wear Wear Diesel | Mobile |
| 1314 | Medium Duty Trucks Diesel Exhaust Stabilized Diesel | Mobile |
| 1315 | Medium Duty Trucks Diesel Tire Wear Wear Diesel | Mobile |
| 1316 | Medium Duty Trucks Diesel Brake Wear Wear Diesel | Mobile |
| 1317 | Light Heavy Duty Trucks (I) Gasoline Exhaust Idle Running Non-Catalytic | Mobile |
| 1318 | Light Heavy Duty Trucks (I) Gasoline Exhaust Cold Start Non-Catalytic | Mobile |
| 1319 | Light Heavy Duty Trucks (I) Gasoline Resting Losses Evaporative Non-Catalytic | Mobile |
| 1320 | Light Heavy Duty Trucks (I) Gasoline Exhaust Idle Running Catalytic | Mobile |
| 1321 | Light Heavy Duty Trucks (I) Gasoline Exhaust Cold Start Catalytic | Mobile |
| 1322 | Light Heavy Duty Trucks (I) Gasoline Resting Losses Evaporative Catalytic | Mobile |
| 1323 | Light Heavy Duty Trucks (I) Diesel Exhaust Idle Running Diesel | Mobile |
| 1324 | Light Heavy Duty Trucks (II) Gasoline Exhaust Stabilized Non-Catalytic | Mobile |
| 1325 | Light Heavy Duty Trucks (II) Gasoline Exhaust Idle Running Non-Catalytic | Mobile |
| 1326 | Light Heavy Duty Trucks (II) Gasoline Exhaust Cold Start Non-Catalytic | Mobile |
| 1327 | Light Heavy Duty Trucks (II) Gasoline Hot Soak Evaporation Evaporative Non-Catalytic | Mobile |
| 1328 | Light Heavy Duty Trucks (II) Gasoline Running Evaporation Evaporative Non-Catalytic | Mobile |
| 1329 | Light Heavy Duty Trucks (II) Gasoline Resting Losses Evaporative Non-Catalytic | Mobile |
| 1330 | Light Heavy Duty Trucks (II) Gasoline Diurnal Breathing Evaporative Non-Catalytic | Mobile |
| 1331 | Light Heavy Duty Trucks (II) Gasoline Tire Wear Wear Non-Catalytic | Mobile |
| 1332 | Light Heavy Duty Trucks (II) Gasoline Brake Wear Wear Non-Catalytic | Mobile |
| 1333 | Light Heavy Duty Trucks (II) Gasoline Exhaust Stabilized Catalytic | Mobile |
| 1334 | Light Heavy Duty Trucks (II) Gasoline Exhaust Idle Running Catalytic | Mobile |
| 1335 | Light Heavy Duty Trucks (II) Gasoline Exhaust Cold Start Catalytic | Mobile |
| 1336 | Light Heavy Duty Trucks (II) Gasoline Hot Soak Evaporation Evaporative Catalytic | Mobile |
| 1337 | Light Heavy Duty Trucks (II) Gasoline Running Evaporation Evaporative Catalytic | Mobile |
| 1338 | Light Heavy Duty Trucks (II) Gasoline Resting Losses Evaporative Catalytic | Mobile |
| 1339 | Light Heavy Duty Trucks (II) Gasoline Diurnal Breathing Evaporative Catalytic | Mobile |
| 1340 | Light Heavy Duty Trucks (II) Gasoline Tire Wear Wear Catalytic | Mobile |
| 1341 | Light Heavy Duty Trucks (II) Gasoline Brake Wear Wear Catalytic | Mobile |
| 1342 | Light Heavy Duty Trucks (II) Diesel Exhaust Stabilized Diesel | Mobile |
| 1343 | Light Heavy Duty Trucks (II) Diesel Exhaust Idle Running Diesel | Mobile |
| 1344 | Light Heavy Duty Trucks (II) Diesel Tire Wear Wear Diesel | Mobile |
| 1345 | Light Heavy Duty Trucks (II) Diesel Brake Wear Wear Diesel | Mobile |
| 1346 | Medium Heavy Duty Trucks Gasoline Exhaust Idle Running Non-Catalytic | Mobile |
| 1347 | Medium Heavy Duty Trucks Gasoline Exhaust Cold Start Non-Catalytic | Mobile |
| 1348 | Medium Heavy Duty Trucks Gasoline Resting Losses Evaporative Non-Catalytic | Mobile |
| 1349 | Medium Heavy Duty Trucks Gasoline Exhaust Idle Running Catalytic | Mobile |
| 1350 | Medium Heavy Duty Trucks Gasoline Exhaust Cold Start Catalytic | Mobile |
| 1351 | Medium Heavy Duty Trucks Gasoline Resting Losses Evaporative Catalytic | Mobile |
| 1352 | Medium Heavy Duty Trucks Diesel Exhaust Idle Running Diesel | Mobile |
| 1353 | Heavy Heavy Duty Trucks Gasoline Exhaust Stabilized Non-Catalytic | Mobile |
| 1354 | Heavy Heavy Duty Trucks Gasoline Exhaust Idle Running Non-Catalytic | Mobile |
| 1355 | Heavy Heavy Duty Trucks Gasoline Exhaust Cold Start Non-Catalytic | Mobile |
| 1356 | Heavy Heavy Duty Trucks Gasoline Hot Soak Evaporation Evaporative Non-Catalytic | Mobile |
| 1357 | Heavy Heavy Duty Trucks Gasoline Running Evaporation Evaporative Non-Catalytic | Mobile |
| 1358 | Heavy Heavy Duty Trucks Gasoline Resting Losses Evaporative Non-Catalytic | Mobile |
| 1359 | Heavy Heavy Duty Trucks Gasoline Diurnal Breathing Evaporative Non-Catalytic | Mobile |
| 1360 | Heavy Heavy Duty Trucks Gasoline Tire Wear Wear Non-Catalytic | Mobile |
| 1361 | Heavy Heavy Duty Trucks Gasoline Brake Wear Wear Non-Catalytic | Mobile |
| 1362 | Heavy Heavy Duty Trucks Gasoline Exhaust Stabilized Catalytic | Mobile |
| 1363 | Heavy Heavy Duty Trucks Gasoline Exhaust Idle Running Catalytic | Mobile |
| 1364 | Heavy Heavy Duty Trucks Gasoline Exhaust Cold Start Catalytic | Mobile |
| 1365 | Heavy Heavy Duty Trucks Gasoline Hot Soak Evaporation Evaporative Catalytic | Mobile |
| 1366 | Heavy Heavy Duty Trucks Gasoline Running Evaporation Evaporative Catalytic | Mobile |
| 1367 | Heavy Heavy Duty Trucks Gasoline Resting Losses Evaporative Catalytic | Mobile |
| 1368 | Heavy Heavy Duty Trucks Gasoline Diurnal Breathing Evaporative Catalytic | Mobile |
| 1369 | Heavy Heavy Duty Trucks Gasoline Tire Wear Wear Catalytic | Mobile |
| 1370 | Heavy Heavy Duty Trucks Gasoline Brake Wear Wear Catalytic | Mobile |
| 1371 | Heavy Heavy Duty Trucks Diesel Exhaust Idle Running Diesel | Mobile |
| 1372 | School Buses Gasoline Exhaust Stabilized Non-Catalytic | Mobile |
| 1373 | School Buses Gasoline Exhaust Cold Start Non-Catalytic | Mobile |
| 1374 | School Buses Gasoline Hot Soak Evaporation Evaporative Non-Catalytic | Mobile |
| 1375 | School Buses Gasoline Running Evaporation Evaporative Non-Catalytic | Mobile |
| 1376 | School Buses Gasoline Resting Losses Evaporative Non-Catalytic | Mobile |
| 1377 | School Buses Gasoline Diurnal Breathing Evaporative Non-Catalytic | Mobile |
| 1378 | School Buses Gasoline Tire Wear Wear Non-Catalytic | Mobile |
| 1379 | School Buses Gasoline Brake Wear Wear Non-Catalytic | Mobile |
| 1380 | School Buses Gasoline Exhaust Stabilized Catalytic | Mobile |
| 1381 | School Buses Gasoline Exhaust Cold Start Catalytic | Mobile |
| 1382 | School Buses Gasoline Hot Soak Evaporation Evaporative Catalytic | Mobile |
| 1383 | School Buses Gasoline Running Evaporation Evaporative Catalytic | Mobile |
| 1384 | School Buses Gasoline Resting Losses Evaporative Catalytic | Mobile |
| 1385 | School Buses Gasoline Diurnal Breathing Evaporative Catalytic | Mobile |
| 1386 | School Buses Gasoline Tire Wear Wear Catalytic | Mobile |
| 1387 | School Buses Gasoline Brake Wear Wear Catalytic | Mobile |
| 1388 | School Buses Diesel Exhaust Stabilized Diesel | Mobile |
| 1389 | School Buses Diesel Tire Wear Wear Diesel | Mobile |
| 1390 | School Buses Diesel Brake Wear Wear Diesel | Mobile |
| 1391 | Urban Buses Gasoline Exhaust Stabilized Non-Catalytic | Mobile |
| 1392 | Urban Buses Gasoline Exhaust Cold Start Non-Catalytic | Mobile |
| 1393 | Urban Buses Gasoline Hot Soak Evaporation Evaporative Non-Catalytic | Mobile |
| 1394 | Urban Buses Gasoline Running Evaporation Evaporative Non-Catalytic | Mobile |
| 1395 | Urban Buses Gasoline Resting Losses Evaporative Non-Catalytic | Mobile |
| 1396 | Urban Buses Gasoline Diurnal Breathing Evaporative Non-Catalytic | Mobile |
| 1397 | Urban Buses Gasoline Tire Wear Wear Non-Catalytic | Mobile |
| 1398 | Urban Buses Gasoline Brake Wear Wear Non-Catalytic | Mobile |
| 1399 | Urban Buses Gasoline Exhaust Stabilized Catalytic | Mobile |
| 1400 | Urban Buses Gasoline Exhaust Cold Start Catalytic | Mobile |
| 1401 | Urban Buses Gasoline Hot Soak Evaporation Evaporative Catalytic | Mobile |
| 1402 | Urban Buses Gasoline Running Evaporation Evaporative Catalytic | Mobile |
| 1403 | Urban Buses Gasoline Resting Losses Evaporative Catalytic | Mobile |
| 1404 | Urban Buses Gasoline Diurnal Breathing Evaporative Catalytic | Mobile |
| 1405 | Urban Buses Gasoline Tire Wear Wear Catalytic | Mobile |
| 1406 | Urban Buses Gasoline Brake Wear Wear Catalytic | Mobile |
| 1407 | Motor Homes Gasoline Exhaust Stabilized Non-Catalytic | Mobile |
| 1408 | Motor Homes Gasoline Exhaust Cold Start Non-Catalytic | Mobile |
| 1409 | Motor Homes Gasoline Hot Soak Evaporation Evaporative Non-Catalytic | Mobile |
| 1410 | Motor Homes Gasoline Running Evaporation Evaporative Non-Catalytic | Mobile |
| 1411 | Motor Homes Gasoline Resting Losses Evaporative Non-Catalytic | Mobile |
| 1412 | Motor Homes Gasoline Diurnal Breathing Evaporative Non-Catalytic | Mobile |
| 1413 | Motor Homes Gasoline Tire Wear Wear Non-Catalytic | Mobile |
| 1414 | Motor Homes Gasoline Brake Wear Wear Non-Catalytic | Mobile |
| 1415 | Motor Homes Gasoline Exhaust Stabilized Catalytic | Mobile |
| 1416 | Motor Homes Gasoline Exhaust Cold Start Catalytic | Mobile |
| 1417 | Motor Homes Gasoline Hot Soak Evaporation Evaporative Catalytic | Mobile |
| 1418 | Motor Homes Gasoline Running Evaporation Evaporative Catalytic | Mobile |
| 1419 | Motor Homes Gasoline Resting Losses Evaporative Catalytic | Mobile |
| 1420 | Motor Homes Gasoline Diurnal Breathing Evaporative Catalytic | Mobile |
| 1421 | Motor Homes Gasoline Tire Wear Wear Catalytic | Mobile |
| 1422 | Motor Homes Gasoline Brake Wear Wear Catalytic | Mobile |
| 1423 | Motor Homes Diesel Exhaust Stabilized Diesel | Mobile |
| 1424 | Motor Homes Diesel Tire Wear Wear Diesel | Mobile |
| 1425 | Motor Homes Diesel Brake Wear Wear Diesel | Mobile |
| 1426 | Motorcycles Gasoline Exhaust Stabilized Catalytic | Mobile |
| 1427 | Motorcycles Gasoline Exhaust Cold Start Catalytic | Mobile |
| 1428 | Motorcycles Gasoline Hot Soak Evaporation Evaporative Catalytic | Mobile |
| 1429 | Motorcycles Gasoline Running Evaporation Evaporative Catalytic | Mobile |
| 1430 | Motorcycles Gasoline Resting Losses Evaporative Catalytic | Mobile |
| 1431 | Motorcycles Gasoline Diurnal Breathing Evaporative Catalytic | Mobile |
| 1432 | Motorcycles Gasoline Tire Wear Wear Catalytic | Mobile |
| 1433 | Motorcycles Gasoline Brake Wear Wear Catalytic | Mobile |
| 1436 | School Buses Gasoline Exhaust Idle Running Catalytic | Mobile |
| 1437 | School Buses Gasoline Exhaust Idle Running Non-Catalytic | Mobile |
| 1438 | School Buses Diesel Exhaust Idle Running Diesel | Mobile |
| 1724 | Other Buses Gasoline Exhaust Cold Start Catalytic | Mobile |
| 1725 | Other Buses Gasoline Exhaust Cold Start Non-Catalytic | Mobile |
| 1726 | Other Buses Gasoline Exhaust Stabilized Catalytic | Mobile |
| 1727 | Other Buses Gasoline Exhaust Stabilized Non-Catalytic | Mobile |
| 1728 | Other Buses Diesel Exhaust Stabilized Diesel | Mobile |
| 1729 | Other Buses Gasoline Exhaust Idle Running Catalytic | Mobile |
| 1730 | Other Buses Gasoline Exhaust Idle Running Non-Catalytic | Mobile |
| 1731 | Other Buses Diesel Exhaust Idle Running Diesel | Mobile |
| 1732 | Other Buses Gasoline Running Evaporation Evaporative Catalytic | Mobile |
| 1733 | Other Buses Gasoline Running Evaporation Evaporative Non-Catalytic | Mobile |
| 1734 | Other Buses Gasoline Diurnal Breathing Evaporative Catalytic | Mobile |
| 1735 | Other Buses Gasoline Diurnal Breathing Evaporative Non-Catalytic | Mobile |
| 1736 | Other Buses Gasoline Resting Losses Evaporative Catalytic | Mobile |
| 1737 | Other Buses Gasoline Resting Losses Evaporative Non-Catalytic | Mobile |
| 1738 | Other Buses Gasoline Hot Soak Evaporation Evaporative Catalytic | Mobile |
| 1739 | Other Buses Gasoline Hot Soak Evaporation Evaporative Non-Catalytic | Mobile |
| 1740 | Other Buses Gasoline Tire Wear Wear Catalytic | Mobile |
| 1741 | Other Buses Gasoline Tire Wear Wear Non-Catalytic | Mobile |
| 1742 | Other Buses Diesel Tire Wear Wear Diesel | Mobile |
| 1743 | Other Buses Gasoline Brake Wear Wear Catalytic | Mobile |
| 1744 | Other Buses Gasoline Brake Wear Wear Non-Catalytic | Mobile |
| 1745 | Other Buses Diesel Brake Wear Wear Diesel | Mobile |
| 2275 | Light Duty Passenger Gasoline Diurnal Breathing Evaporative Electric | Mobile |
| 2276 | Light Duty Passenger Gasoline Resting Losses Evaporative Electric | Mobile |
| 2277 | Light Duty Passenger Gasoline Hot Soak Evaporation Evaporative Electric | Mobile |
| 2278 | Light Duty Passenger Gasoline Tire Wear Wear Electric | Mobile |
| 2279 | Light Duty Passenger Gasoline Brake Wear Wear Electric | Mobile |
| 2280 | Light Duty Trucks (I) Gasoline Diurnal Breathing Evaporative Electric | Mobile |
| 2281 | Light Duty Trucks (I) Gasoline Resting Losses Evaporative Electric | Mobile |
| 2282 | Light Duty Trucks (I) Gasoline Hot Soak Evaporation Evaporative Electric | Mobile |
| 2283 | Light Duty Trucks (I) Gasoline Tire Wear Wear Electric | Mobile |
| 2284 | Light Duty Trucks (I) Gasoline Brake Wear Wear Electric | Mobile |
| 2285 | Medium Heavy Duty Trucks Diesel Exhaust Cold Start Diesel | Mobile |
| 2286 | Heavy Heavy Duty Trucks Diesel Exhaust Cold Start Diesel | Mobile |
| 2287 | School Buses Diesel Exhaust Cold Start Diesel | Mobile |
| 2288 | Other Buses Diesel Exhaust Cold Start Diesel | Mobile |
| 2544 | Light Duty Trucks (II) Gasoline Diurnal Breathing Evaporative Electric | Mobile |
| 2545 | Light Duty Trucks (II) Gasoline Hot Soak Evaporation Evaporative Electric | Mobile |
| 2546 | Light Duty Trucks (II) Gasoline Brake Wear Wear Electric | Mobile |
| 2547 | Light Duty Trucks (II) Gasoline Tire Wear Wear Electric | Mobile |
| 2548 | Light Duty Trucks (II) Gasoline Resting Losses Evaporative Electric | Mobile |
| 2549 | Medium Duty Trucks Gasoline Diurnal Breathing Evaporative Electric | Mobile |
| 2550 | Medium Duty Trucks Gasoline Hot Soak Evaporation Evaporative Electric | Mobile |
| 2551 | Medium Duty Trucks Gasoline Brake Wear Wear Electric | Mobile |
| 2552 | Medium Duty Trucks Gasoline Tire Wear Wear Electric | Mobile |
| 2553 | Medium Duty Trucks Gasoline Resting Losses Evaporative Electric | Mobile |
| 2554 | Urban Buses Gasoline Brake Wear Wear Electric | Mobile |
| 2555 | Urban Buses Gasoline Tire Wear Wear Electric | Mobile |
9.17.8 Contact
Author: Yuan Du
Reviewer: Abhinav Guha, Tan Dinh
Last Update: November 06, 2023
9.17.9 References & Footnotes
California Air Resources Board (CARB). MSEI - Modeling Tools - EMFAC Software and Technical Support Documentation. Accessed in May 2020. https://ww2.arb.ca.gov/our-work/programs/mobile-source-emissions-inventory/msei-modeling-tools-emfac-software-and↩︎
California Air Resources Board (CARB). Public Release of EMFAC2017 Update, v1.0.2. March 2018 https://ww2.arb.ca.gov/sites/default/files/2023-01/emfac2017-public-release-notice-v1.0.2.pdf↩︎
CARB. EMFAC Off-Model Adjustment Factors to Account for the SAFE Vehicle Rule Part One. November 20, 2019. https://ww2.arb.ca.gov/sites/default/files/2023-02/emfac_off_model_co2_adjustment_factors_06262020-final.pdf↩︎