CHAPTER 3 

BASE YEAR AND FUTURE EMISSIONS 

Introduction

Emission Inventories 

Base Year Emissions

Future Emissions 

Top Ten Source Categories (2002, 2014, 2023) 
Chapter 3 Base Year and Future Emissions 

3-1

INTRODUCTION 

This chapter summarizes emissions that occurred in the Basin during the base year 2002, 

and projected emissions in the years 2014, 2020, and 2023. More detailed emission data 

analyses are presented in Appendix III of the Final 2007 AQMP. Additional emission 

inventories for other interim years (i.e., 2005, 2008, 2010, 2011, 2017, and 2030) are 

also developed. These inventory years are selected to comply with federal and state 

Clean Air Act requirements. The 2002 base year emissions inventory reflects adopted 

air regulations with current compliance dates as of 2002; whereas future baseline 

emissions inventories are based on adopted air regulations with both current and future 

compliance dates. A list of AQMD and CARB rules and regulations that are part of the 

base year and future-year baseline emissions inventories is presented in Appendix III of 

the Final 2007 AQMP. The District is committed to implement the AQMD rules that are 

incorporated in the Final 2007 AQMP baseline emissions inventories. 

The emissions inventory is divided into four major classifications: point, area, off-road, 

and on-road sources. The 2002 base year point source emissions are based principally 

on reported data from facilities. The area source and off-road emissions are estimated 

jointly by CARB and the District. The on-road emissions are calculated using the 

CARB EMFAC2007 V2.3 emission factors and the transportation activity data provided 

by SCAG from their modified 2004 Regional Transportation Plan (2004 RTP). In this 

document Outer Continental Shelf (OCS) emissions (i.e. ships beyond the three-mile 

state waters line) are included in the ships emissions. The future emission forecasts are 

based on demographic and economic growth projections provided by the Southern 

California Association of Governments (SCAG). In addition, emission reductions 

resulting from District regulations adopted by June 30, 2006 are included in the emission 

forecasts. CARB regulations adopted by June 2005 were included in the baseline. 

Several additional adjustments were made to EMFAC2007 V2.3 to make additional 

technical corrections to the inventory. The most significant adjustment was the 

application of a factor (0.78) to the 2005 heavy heavy-duty diesel truck emissions to 

correct the population estimates previously assumed in the inventory. Other adjustments 

were made to on-road categories in order to account for CARB’s adopted rules which 

are not included in EMFAC2007 V2.3. Categories affected by this change included 

light-duty passenger cars, light-, medium-, and heavy-duty trucks, buses, and motor 

homes. 

Off-road emissions were updated using CARB’s November 1, 2006 OFFROAD model. 

External adjustments were also made for inventory categories such as ships, dredging, 

industrial equipment, lawn and garden equipment, and others. Adjustments were made 

after the model was finalized to reflect information revising activity levels and patterns, 

and to include Carl Moyer benefits and CARB’s adopted rules which are not included in 

the OFFRAD model. 
Final 2007 AQMP 

3-2

This chapter also includes information on the top ten source categories that contribute to 

the majority of the emissions inventory in 2002, 2014, and 2023. The data for the year 

2023 is being presented because the South Coast will need to request a “bump up” in 

attainment classification. Data for 2020 is included in portions of this Chapter and in 

Appendix III. Please see Chapter 12 for more information on the attainment status. 

EMISSION INVENTORIES 

Three inventories are prepared for the Final 2007 AQMP for the purpose of regulatory 

and SIP performance tracking and transportation conformity: an annual average 

inventory, a summer planning inventory, and a winter planning inventory. Baseline 

emissions data presented in this chapter are based on average annual day emissions (i.e., 

total annual emissions divided by 365 days) and seasonally adjusted planning inventory 

emissions. The Final 2007 AQMP uses annual average day emissions to estimate the 

cost-effectiveness of control measures, to rank control measure implementation, and to 

perform PM2.5 modeling and analysis. The planning inventory emissions developed to 

capture the emission levels during a poor air quality season are used to report emission 

reduction progress as required by the federal and state Clean Air Acts. 

Detailed descriptions of the base year and future baseline emission inventories are 

presented in Appendix III of the Final 2007 AQMP. 

Attachment F to Appendix III shows emissions associated with combustion of diesel fuel 

for various source categories. 

Stationary Sources 

Stationary sources can be divided into two major subcategories: point and area sources. 

Point sources are generally large emitters with one or more emission sources at a 

permitted facility with an identified location (e.g., power plants, refineries). Area 

sources generally consist of many small emission sources (e.g., residential water heaters, 

architectural coatings) which are distributed across the region. Their emissions over a 

given area may be calculated using socioeconomic data. For 2002, reported data are 

used for point sources emitting more than 4 tons per year of the following criteria air 

contaminants: VOC, NOx, SOx, and PM2.5. For CO, facilities report if they are over 

100 tons per year. If any of these thresholds are triggered, all pollutants are reported by 

the facility. 

Area source emissions were jointly developed by CARB and the District for 

approximately 350 categories. Several special studies were conducted to improve the 

area source inventory. Specific source categories such as gasoline dispensing, consumer 

products, architectural coatings, fugitive dust, and ammonia sources were updated (see 

Appendix III). For consumer products and architectural coatings, revised and updated 
Chapter 3 Base Year and Future Emissions 

3-3

survey data were used. For fugitive dust, the PM10 to PM2.5 ratio was changed based 

on a study by the Western Regional Air Partnership (WRAP). 

Mobile Sources 

Mobile sources consist of two subcategories: on-road and off-road sources. On-road 

vehicle emissions are calculated using socioeconomic data and transportation models 

provided by SCAG, spatial distribution data from Caltrans’ Direct Travel Impact Model 

(DTIM4), and EMFAC2007 V2.3 inventories obtained from CARB. The EMFAC2007 

V2.3 reflects SCAG’s revised baseline activity data from the modified 2004 RTP. The 

2000 Census data, combined with SCAG’s 2001 origin and destination survey data, are 

used in SCAG’s modified 2004 RTP and in this AQMP. Major improvements made to 

the EMFAC2007 V2.3 include: 

1. Heavy heavy-duty diesel vehicles population redistribution; 

2. Vehicle miles traveled updates; 

3. Heavy heavy-duty diesel factors updates; 

4. Pending vehicles updates; 

5. Fuel correcting factors updates; 

6. Ethanol permeation effects; 

7. New population data; and 

8. New temperature and relative humidity profiles corresponding to the federal 8-

hour ozone standard. 

Figure 3-1A compares the on-road baseline emissions between EMFAC2002 and the 

EMFAC2007 V2.3 used in the 2003 AQMP and Final 2007 AQMP, respectively. It 

should be noted that the comparison for 2002 reflects changes in methodology, but 2020 

also includes adopted rules, and updated growth projections since the release of 

EMFAC2002. 

Emissions from off-road vehicle categories (e.g., trains, ships, construction equipment, 

ports and rail cargo handling equipment) were developed primarily based on estimated 

activity levels and emission factors. The major changes made to the off-road model 

include: 

1. Off-road equipment population, activity, and emission factor updates; 

2. Locomotive inventory reflecting the 1998 South Coast Locomotive MOU and 

the 2005 CARB/Railroad MOU; 
Final 2007 AQMP 

3-4

3. Cargo handling equipment updates; 

4. Portable fuel containers updates; 

5. Marine vessel updates; and 

6. Commercial harbor craft updates. 

The inventory for trains was revised from the 2003 AQMP to reflect projected emission 

reductions based on the 1998 South Coast MOU and the 2005 CARB/Railroad MOU. 

Significant inventory improvements have been made to the marine vessel category, 

which includes ocean-going vessels, commercial harbor craft, and other ships. For both 

the Port of Los Angeles and Port of Long Beach, more recent and comprehensive 

emission inventories and projections have been included in the Final 2007 AQMP. New 

surveys and data sources for marine vessels have been used, as described in Appendix 

III. 

Figure 3-1B shows a comparison of the off-road baseline emissions based on the 

OFFROAD model revisions used for the 2003 AQMP and Final 2007 AQMP. As the 

inventory methodology has improved, more emissions have been quantified, resulting in 

equal or higher emissions than previously anticipated in spite of more rules being 

adopted. This creates a greater challenge for attainment. 

Uncertainty in the Inventory 

An effective AQMP relies on an adequate emission inventory. Over the years, 

significant improvements have been made to quantify emission sources upon which 

control measures are developed. Increased use of continuous monitoring and source 

tests has contributed to the improvement in point source inventories. Technical 

assistance to facilities and auditing of reported emissions by the District also have 

improved the accuracy of the emissions inventory. Area source inventories that rely on 

average emission factors and regional activities have inherent uncertainty. Industryspecific surveys or source-specific studies during rule development have provided muchneeded refinement to the emissions estimates. 

Mobile source inventories remain the greatest challenge due to the high number and 

types of equipment and engines involved, in-use performance variables, and complex 

emission characteristics. Every AQMP revision provides an opportunity to further 

improve the current knowledge of mobile source inventories. There is no exception to 

the Final 2007 AQMP. As described earlier, many improvements were made to the 

EMFAC2007 V2.3 and such work is still ongoing. However, it should be acknowledged 

that there are still areas that may not have been adequately addressed. For example, 

ethanol permeation not accounted for in the stationary source inventory for gasolinepowered equipment or gas stations, how best to reflect heavy heavy-duty truck in-use 

emissions with limited test data, and appropriate spatial and temporal distribution of 
Chapter 3 Base Year and Future Emissions 

3-5

recreational boats need to be examined further. The best available science should be 

followed to support the AQMP development. 

Relative to future growth, there are many challenges with making accurate projections. 

For example, where vehicle trips will occur, the distribution between various modes of 

transportation (such as trucks and trains), as well as estimates for population growth and 

changes to the number and type of jobs – although they are forecast with the best 

information available; nevertheless, they contribute to the overall uncertainty in emission 

projections. 

Gridded Emissions 

For air quality modeling purposes, the region is composed of the South Coast Air Basin, 

Coachella Valley, Antelope Valley, Ventura County (upwind area), and Mojave Desert. 

The modeling area is divided into a grid system composed of 5 km by 5 km grid cells 

defined by Universal Transverse Mercator (UTM) coordinates. Both stationary and 

mobile source emissions are allocated to individual grid cells within this system. In 

general, the modeling emission data features episodic-day emissions. Seasonal 

variations in activity levels are taken into account in developing gridded stationary point 

and area source emissions. Variations in temperature, hours of operation, speed of 

motor vehicles, or other factors are considered in developing gridded motor vehicle 

emissions. Hence, “gridded” emissions data used for ozone modeling applications 

(Chapter 5) differ from the average annual day or planning inventory emission data in 

two respects: 1) the modeling region covers larger geographic areas than the Basin; and 

2) emissions represent day-specific instead of average or seasonal conditions. In the 

Final 2007 AQMP, gridded inventories associated with selected ozone episodes have 

been prepared for air quality modeling analyses. In addition, gridded emissions for 2005 

and 2014 were developed to calculate annual average PM2.5 concentrations. 
Final 2007 AQMP 

3-6

FIGURE 3-1A 

Comparison of On-Road Emissions Between EMFAC2002 (2003 AQMP) 

and EMFAC2007 V2.3 (Final 2007 AQMP) 

(VOC & NOx – Summer Planning; SOx & PM2.5 – Annual Average Inventory) 

* Year 2020 inventories incorporate rules adopted since the release of EMFAC2002. 

** Redistribution of the heavy-duty truck VMT in the EMFAC2007 V2.3 causes heavy duty truck VMT reduction in the 

SCAB. As a result, NOx and SOx emissions are relatively lower in the Final 2007 AQMP than in the 2003 AQMP. 

Note: External adjustments to the EMFA2007 V2.3 are included. 

2003 AQMP 2007 AQMP * 

117

337

114

360

0

50

100

150

200

250

300

350

400

2002 2020

VOC

Tons/Day

187

645

184

611**

0

100

200

300

400

500

600

700

800

2002 2020

NOx

Tons/Day

13 13

16

18

0

2

4

6

8

10

12

14

16

18

20

2002 2020

PM2.5

Tons/Day

2

5

2

4 **

0

1

2

3

4

5

6

2002 2020

SOx

Tons/Day
Chapter 3 Base Year and Future Emissions 

3-7

FIGURE 3-1B 

Comparison of Off-Road Emissions Between 2003 AQMP and Final 2007 AQMP 

(VOC & NOx – Summer Planning; SOx & PM2.5 – Annual Average Inventory) 

* Year 2020 inventories incorporate rules adopted since the release of EMFAC2002

2003 AQMP 2007 AQMP * 

125

222

146

219

0

50

100

150

200

250

2002 2020

VOC

Tons/Day

54

33 32

27

0

10

20

30

40

50

60

2002 2020

SOx

Tons/Day

16

19

15

21

0

5

10

15

20

25

2002 2020

PM2.5

Tons/Day

250

323

271

378

0

50

100

150

200

250

300

350

400

450

2002 2020 NOx

Tons/Day
Final 2007 AQMP 

3-8

BASE YEAR EMISSIONS 

2002 Emission Inventory 

Tables 3-1A and 3-1B shows the 2002 emissions inventory by major source category. 

Table 3-1A shows annual average emissions, while Table 3-1B shows the planning 

inventories for summer and winter. 

Overall, total mobile source emissions account for 64 percent of the VOC and 91 

percent of the NOx emissions for these two ozone-forming pollutants, based on the 

annual average inventory. The on-road mobile category alone contributes about 43 and 

57 percent of the VOC and NOx emissions, respectively, and approximately 76 percent 

of the CO for the annual average inventory. 

Figure 3-2 characterizes relative contributions by stationary and mobile source 

categories. Stationary sources are subdivided into point (e.g., chemical manufacturing, 

petroleum production, and electric utilities) and area sources (e.g., architectural coatings, 

residential water heaters, and consumer products). Mobile sources consist of on-road 

(e.g., light-duty passenger cars) and off-road sources (e.g., trains and ships). Entrained 

road dust is also included in Figure 3-2. 

On- and off-road sources continue to be the major contributors for each of the 5 

pollutants, as seen in Figure 3-2. For example, mobile sources represent 64 percent of 

VOC emissions, 92 percent of NOx emissions, and 98 percent of CO emissions. For 

directly emitted PM2.5, mobile sources represent 39 percent of the emissions with 

another 20 percent due to vehicle-related entrained road dust. 

Within the category of stationary sources, point sources contribute more SOx emissions 

than area sources. Area sources play a major role in VOC emissions, emitting about five 

times more than point sources. Area sources are the predominant source (32 percent) of 

directly emitted PM2.5 emissions, including sources such as cooking. 
Chapter 3 Base Year and Future Emissions 

3-9

TABLE 3-1A 

Summary of Emissions By Major Source Category: 2002 Base Year 

Average Annual Day (tons/day1

) 

Source Category VOC NOx CO SOx PM2.5 

Stationary Sources 

 Fuel Combustion 7 35 52 2 6 

 Waste Disposal 7 2 1 0 0 

 Cleaning and Surface Coatings 54 0 0 0 1 

 Petroleum Production and Marketing 35 0 9 7 1 

 Industrial Processes 21 0 2 0 5 

 Solvent Evaporation 

 Consumer Products 110 0 0 0 0 

 Architectural Coatings 49 0 0 0 0 

 Others 3 0 0 0 0 

 Misc. Processes * 16 27 62 0 47 

 RECLAIM Sources 0 29 0 12 0 

Total Stationary Sources 302 93 126 22 60 

Mobile Sources 

 On-Road Vehicles 362 628 3677 4 18 

 Off-Road Vehicles 180 372 1016 27 21 

Total Mobile Sources 542 1000 4693 31 39 

TOTAL 844 1093 4819 53 99 

TABLE 3-1B 

Summary of Emissions By Major Source Category: 2002 Base Year 

Planning Inventory** (tons/day1

) 

SUMMER 

OZONE PRECURSORS

WINTER 

INVENTORY

Source Category VOC NOx NOx CO 

Stationary Sources 

 Fuel Combustion 7 36 35 54 

 Waste Disposal 8 2 2 1 

 Cleaning and Surface Coatings 60 0 0 0 

 Petroleum Production and Marketing 35 1 1 9 

 Industrial Processes 22 0 0 2 

 Solvent Evaporation 

 Consumer Products 110 0 0 0 

 Architectural Coatings 57 0 0 0 

 Others 4 0 0 0 

 Misc. Processes 14 21 33 102 

 RECLAIM SOURCES 0 29 29 0 

Total Stationary Sources 317 89 100 168 

Mobile Sources 

 On-Road Vehicles 360 611 680 3630 

 Off-Road Vehicles 220 378 367 844 

Total Mobile Sources 580 989 1047 4474 

TOTAL 897 1078 1147 4642 

* Travel-related road dust included. **Planning inventories are not used for PM2.5 analysis. 

1 Values are rounded to nearest integer. 
Final 2007 AQMP 

3-10

VOC Emissions: 897 Tons/Day

30%

6%

40%

24%

FIGURE 3-2 

Relative Contribution by Source Category to 2002 Emission Inventory 

(VOC & NOx – Summer Planning; CO, SOx & PM2.5 – Annual Average Inventory) 

NOx Emissions: 1,079 Tons/Day

4%

4%

57%

35%

CO Emissions: 4,819 Tons/Day

1%

1%

77%

21%

SOx Emissions: 53 Tons/Day

3%

38%

8%

51%

Directly Emitted PM2.5 Emissions: 

99 Tons/Day

20%

32%

9%

18%

21%

On-Road Off-Road Point Area Entrained Road Dust

Note: Consumer products and architectural coatings under the 

area source category represent 110 and 57 tons per day of VOC 

emissions, respectively. 
Chapter 3 Base Year and Future Emissions 

3-11

In the mobile source category, emissions from on-road vehicles are much higher than 

those from off-road sources for all criteria pollutants except SOx and PM2.5. This can 

be explained by the fact that the sulfur content in fuels used for off-road vehicles is 

relatively higher than those for on-road vehicles, and commercial/industrial off-road 

equipment generates high levels of PM2.5. 

FUTURE EMISSIONS 

Data Development 

The milestone years 2002, 2005, 2008, 2010, 2011, 2014, 2017, 2020, 2023, and 2030 

are the target years for emissions rate-of-progress estimates under the federal Clean Air 

Act and the state Clean Air Act. Future emissions are divided into RECLAIM and nonRECLAIM emissions. Future NOx and SOx emissions from RECLAIM sources are 

estimated based on their allocations as specified by AQMD Rule 2002 –Allocations for 

NOx and SOx. The forecasts for non-RECLAIM emissions were derived using: 1) 

emissions from the 2002 base year; 2) expected controls after implementation of District 

rules adopted by June 30, 2006, and most CARB rules adopted as of June 2005; and 3) 

emissions growth in various source categories between the base and future years. 

AQMD rules adopted after June 30, 2006 are treated as baseline adjustments for 

emissions reduction accounting purposes. From efforts currently underway for 

amending Rule 1110.2, staff has estimated additional emissions of 1.26 tons per day of 

NOx; 42.07 tons per day of CO; and 7.39 tons per day of VOC in 2005 due to 

unanticipated non compliance. These emissions are expected to be totally controlled by 

year 2008 if the proposed rule amendment, which is scheduled to be brought to the 

Governing Board this year, is adopted. Therefore, these emissions were not added to the 

2007 AQMP inventories. 

Demographic growth forecasts for various socioeconomic categories (e.g., population, 

housing, employment by industry), developed by SCAG for their interim 2007 RTP, 

were used in the modified 2004 RTP to estimate future emissions. Industry growth 

factors for 2002, 2005, 2010, 2015, 2020, 2025, and 2030 were provided by SCAG. 

Growth factors for other interim years were interpolated between key forecast years. 

Table 3-2 summarizes key socioeconomic parameters used in the Final 2007 AQMP for 

emissions inventory development. 
Final 2007 AQMP 

3-12

TABLE 3-2 

Baseline Demographic Forecasts in the Final 2007 AQMP 

Category 2002 2020 (% Growth) 2030 (% Growth) 

Population 

(Millions) 

15.1 18.4 22% 19.6 30% 

Housing Units 

(Millions) 

4.8 5.9 23% 6.4 33% 

Total Employment 

(Millions) 

6.8 8.2 21% 9.0 32% 

Daily VMT 

(Millions) 

349 414 19% 453 30% 

______________________________________________________________________________________ 

Current forecasts indicate that this region will experience a population growth of 22 

percent by the year 2020 with a 19 percent increase in vehicle miles traveled (VMT). 

As compared to the projection from the 2003 AQMP, the current projection for the year 

2020 shows about a 200,000 (1%) increase in population, 300,000 (3.5%) decrease in 

total employment and 40.7 million mile ( 9%) decrease in the daily VMT forecast. The 

decrease in VMT forecast is primarily due to the redistribution of VMT to the eastern 

portion of the region outside of the SCAB. 

CARB staff revised assumptions related to pending vehicle registrations, which affects 

emissions as well. EMFAC2007 includes an assumption that 25 percent of these 

vehicles are on the road, rather than the 100 percent estimate used in the EMFAC2007 

Working Draft. 

Comparing EMFAC2007 VMT to projections from SCAG shows a significant “blip” or 

increase in VMT between 2002 and 2005, although 2010 VMT decreases and 

projections for 2010 and beyond are very close between EMFAC2007 and SCAG 

estimates. The District staff retained two technical experts in the area of transportation 

analysis to review the VMT estimates for 2005. The consultants reviewed CARB’s 

assumptions and, to the extent possible, some of the DMV and BAR data used to 

produce the 2005 VMT estimates. They concluded that there is no independent evidence 

to support a decline in VMT between 2005 and 2010, and recommended conducting a 

sensitivity analysis in the near term, to determine the magnitude of the differences. 

Detailed discussions on the VMT sensitivity analysis is contained in Appendix-V of the 

Final 2007 AQMP. Based on the analysis, the District staff recommends that for 

purposes of attainment demonstration VMT estimates provided by SCAG be used 

instead of EMFAC2007. 
Chapter 3 Base Year and Future Emissions 

3-13

Summary of Baseline Emissions 

Emission data by source categories (point, area, on-road mobile and off-road mobile 

sources) and by pollutants are presented in Tables 3-3 through 3-5 for the years 2014, 

2020, and 2023. The tables provide annual average, and summer and winter planning 

inventories. 

Without any additional controls, VOC, NOx, and CO emissions are expected to decrease 

due to existing regulations, such as controls on off-road equipment, new vehicle 

standards, and the RECLAIM program. Figure 3-3 illustrates the relative contribution to 

the 2023 inventory by source category. A comparison between Figures 3-2 and 3-3 

indicates that the on-road mobile category continues to be a major contributor to CO and 

NOx emissions. However, due to the adopted regulations, by 2023 on-road mobile 

accounts for about 19 percent of total VOC emissions compared to 40 percent in 2002. 

Meanwhile, area sources become the major contributor to VOC emissions from 30 

percent in 2002 to 44 percent in 2023. See Figures 3-7 through 3-18 for the top ten 

ranking by source category for 2002, 2014, and 2020. 
Final 2007 AQMP 

3-14

TABLE 3-3A 

Summary of Emissions By Major Source Category: 2014 Base Year 

Average Annual Day (tons/day1

) 

Source Category VOC NOx CO SOx PM2.5 

Stationary Sources 

 Fuel Combustion 7 24 51 3 6 

 Waste Disposal 8 2 1 0 1 

 Cleaning and Surface Coatings 41 0 0 0 1 

 Petroleum Production and Marketing 32 0 8 1 1 

 Industrial Processes 21 0 3 0 5 

 Solvent Evaporation 

 Consumer Products 107 0 0 0 0 

 Architectural Coatings 24 0 0 0 0 

 Others 3 0 0 0 0 

 Misc. Processes* 14 23 115 0 55 

 RECLAIM Sources 0 27 0 12 0 

Total Stationary Sources 257 76 178 16 69 

Mobile Sources 

 On-Road Vehicles 144 293 1393 2 17 

 Off-Road Vehicles 127 285 1006 25 16 

Total Mobile Sources 271 578 2399 27 33 

TOTAL 528 654 2577 43 102 

TABLE 3-3B 

Summary of Emissions By Major Source Category: 2014 Base Year 

Planning Inventory** (tons/day1

) 

SUMMER 

OZONE PRECURSORS

WINTER 

INVENTORY

Source Category VOC NOx NOx CO

Stationary Sources 

 Fuel Combustion 7 25 24 53 

 Waste Disposal 8 2 2 1 

 Cleaning and Surface Coatings 45 0 0 0 

 Petroleum Production and Marketing 33 0 0 8 

 Industrial Processes 23 0 1 3 

 Solvent Evaporation 

 Consumer Products 107 0 0 0 

 Architectural Coatings 29 0 0 0 

 Others 3 0 0 0 

 Misc. Processes 9 17 32 220 

 RECLAIM Sources 0 27 27 0 

Total Stationary Sources 264 71 86 285 

Mobile Sources 

 On-Road Vehicles 148 287 312 1373 

 Off-Road Vehicles 157 292 278 839 

Total Mobile Sources 305 579 590 2212 

TOTAL 569 650 676 2497 

* Travel-related road dust included. **Planning inventories are not used for PM2.5 analysis. 

1 Values are rounded to nearest integer. 
Chapter 3 Base Year and Future Emissions 

3-15

TABLE 3-4A 

Summary of Emissions By Major Source Category: 2020 Base Year 

Average Annual Day (tons/day1

) 

Source Category VOC NOx CO SOx PM2.5 

Stationary Sources 

 Fuel Combustion 7 22 53 3 6 

 Waste Disposal 8 2 1 0 0 

 Cleaning and Surface Coatings 43 0 0 0 1 

 Petroleum Production and Marketing 34 0 8 1 1 

 Industrial Processes 23 1 3 0 6 

 Solvent Evaporation 

 Consumer Products 112 0 0 0 0 

 Architectural Coatings 26 0 0 0 0 

 Others 3 0 0 0 0 

 Misc. Processes* 14 22 119 0 58 

 RECLAIM Sources 0 27 0 12 0 

Total Stationary Sources 270 74 184 16 72 

Mobile Sources 

 On-Road Vehicles 110 187 973 2 16 

 Off-Road Vehicles 119 264 1071 32 15 

Total Mobile Sources 229 451 2044 34 31 

TOTAL 499 525 2228 50 108 

TABLE 3-4B 

Summary of Emissions By Major Source Category: 2020 Base Year 

Planning Inventory** (tons/day1

) 

SUMMER 

OZONE PRECURSORS

WINTER 

INVENTORY

Source Category VOC NOx NOx CO 

Stationary Sources 

 Fuel Combustion 7 24 23 55 

 Waste Disposal 8 2 2 1 

 Cleaning and Surface Coatings 49 0 0 0 

 Petroleum Production and Marketing 34 0 0 8 

 Industrial Processes 25 0 0 4 

 Solvent Evaporation 

 Consumer Products 112 0 0 0 

 Architectural Coatings 30 0 0 0 

 Others 3 0 0 0 

 Misc. Processes 9 15 32 226 

 RECLAIM Sources 0 27 27 0 

Total Stationary Sources 277 68 84 294 

Mobile Sources 

 On-Road Vehicles 114 184 199 958 

 Off-Road Vehicles 147 272 257 895 

Total Mobile Sources 261 456 456 1853 

TOTAL 538 524 540 2147 

* Travel-related road dust included. **Planning inventories are not used for PM2.5 analysis. 

1 Values are rounded to nearest integer. 
Final 2007 AQMP 

3-16

TABLE 3-5A 

Summary of Emissions By Major Source Category: 2023 Base Year 

Average Annual Day (tons/day1

) 

Source Category VOC NOx CO SOx PM2.5 

Stationary Sources 

 Fuel Combustion 7 22 54 3 6 

 Waste Disposal 9 2 1 0 0 

 Cleaning and Surface Coatings 45 0 0 0 1 

 Petroleum Production and Marketing 35 0 8 1 1 

 Industrial Processes 24 0 3 0 6 

 Solvent Evaporation 

 Consumer Products 114 0 0 0 0 

 Architectural 26 0 0 0 0 

 Others 2 0 0 0 0 

 Misc. Processes* 14 23 120 1 59 

 RECLAIM Sources 0 27 0 12 0 

Total Stationary Sources 276 74 186 17 73 

Mobile Sources 

 On-Road Vehicles 99 164 838 2 16 

 Off-Road Vehicles 120 268 1119 36 16 

Total Mobile Sources 219 432 1957 38 32 

TOTAL 495 506 2143 55 105 

TABLE 3-5B 

Summary of Emissions By Major Source Category: 2023 Base Year 

Planning Inventory** (tons/day1

) 

SUMMER 

OZONE PRECURSORS

WINTER 

INVENTORY

Source Category VOC NOx NOx CO 

Stationary Sources 

 Fuel Combustion 7 24 23 55 

 Waste Disposal 9 2 2 1 

 Cleaning and Surface Coatings 50 0 0 0 

 Petroleum Production and Marketing 35 0 0 8 

 Industrial Processes 26 0 1 4 

 Solvent Evaporation 

 Consumer Products 114 0 0 0 

 Architectural 31 0 0 0 

 Others 3 0 0 0 

 Misc. Processes 9 16 32 229 

 RECLAIM Sources 0 27 27 0 

Total Stationary Sources 285 69 85 297 

Mobile Sources 

 On-Road Vehicles 103 161 174 824 

 Off-Road Vehicles 148 276 261 936 

Total Mobile Sources 251 437 435 1760 

TOTAL 536 506 520 2057 

* Travel-related road dust included. **Planning inventories are not used for PM2.5 analysis. 

1 Values are rounded to nearest integer. 
Chapter 3 Base Year and Future Emissions 

3-17

FIGURE 3-3 

Relative Contribution by Source Category to 2023 Emission Inventory 

(VOC & NOx – Summer Planning; CO, SOx & PM2.5 – Annual Average Inventory) 

VOC Emissions: 536 Tons/Day

44%

9%

19%

28%

NOx Emissions: 506 Tons/Day

6%

7%

32%

55%

CO Emissions: 2,143 Tons/Day

6%

3%

39%

52%

Directly Emitted PM2.5 Emissions: 

105 Tons/Day

20%

9% 41%

15%

15%

On-Road Off-Road Point Area Entrained Road Dust

Note: Consumer products and architectural coatings under the 

area source category represent 114 and 31 tons per day of VOC 

emissions, respectively. 

SOx Emissions: 55 Tons/Day

5%

25%

4%

66%
Final 2007 AQMP 

3-18

Impact of Growth 

To illustrate the impact of growth, year 2020 no-growth emissions were estimated by 

removing the growth factors from the 2020 baseline emissions. Figure 3-4 presents the 

comparison of the 2020 projected emissions with and without growth. It should be noted 

that in this analysis the benefit of New Source Review is not included. As shown in Table 

3-2, the growth from year 2002 to 2020 is significant and presents a formidable challenge to 

our air quality improvement efforts. We are expecting 22% growth in population; 23% 

growth in housing units; 21% growth in employment; and 19% growth in vehicle miles 

traveled. The projected growth will offset the impressive progress made in reducing VOC 

and NOx emissions through adopted regulations. To overcome such challenges and meet 

EPA’s more stringent standards necessitates continuing aggressive clean-up efforts from all 

air quality agencies. 

0

100

200

300

400

500

600

VOC - G VOC - NG NOx - G NOx - NG **CO - G **CO - NG SOx - G SOx - NG PM2.5 - G PM2.5 -NG

Point Area Road Dust Off-Road On-Road

* G = Emissions with growth; NG = Emissions without growth 

** CO emissions are divided by 10 

FIGURE 3-4 

2020 Emissions Forecast With and Without Growth 

(VOC & NOx – Summer Planning; CO, SOx & PM2.5 – Annual Average Inventory) 

538 

422 

524

386 

223

174

50 36

103 

84
Chapter 3 Base Year and Future Emissions 

3-19

Locomotive Emissions 

To illustrate the impact of growth on future emissions, the following information on 

locomotive emissions is provided. As part of the emissions inventory development, all 

adopted regulatory actions affecting future emissions limits are built into the baseline 

emissions inventory estimates. Relative to locomotive emissions, emission reductions 

associated with the current federal emissions standards, fuel standards, and the state 

MOU with the two major locomotive operators have been incorporated into the future 

projected baseline emissions inventory out to 2030. In addition, projected future 

economic growth has been incorporated into the baseline inventories. 

0

5

10

15

20

25

30

35

40

2002

2004

2006

2008

2010

2012

2014

2016

2018

2020

2022

2024

2026

2028

2030

Year

NOx (tpd)

FIGURE 3-5A 

Locomotive NOx 

Baseline Emissions Trend 
Final 2007 AQMP 

3-20

0.70

0.75

0.80

0.85

0.90

2002

2004

2006

2008

2010

2012

2014

2016

2018

2020

2022

2024

2026

2028

2030

Year

PM2.5 (tpd)

FIGURE 3-5B 

Locomotive PM2.5 

Baseline Emissions Trend 

The 1998 California MOU with the locomotive industry would require that the railroads 

meet a fleetwide Tier 2 locomotive emission standard on average to operate in the South 

Coast Air Basin. As shown in Figures 3-5 and 3-6, the South Coast would show a 

somewhat greater benefit in having cleaner engines earlier. In addition, the use of lower 

sulfur diesel fuel is expected to have a measurable benefit in NOx and PM emission 

reductions beginning in 2010. However, after 2012 there is a steady increase in 

emissions due to future growth projected for the rail industry. This growth is expected 

to overtake the benefits of the cleaner Tier 2 locomotives and low sulfur fuel standards. 

There is also significant uncertainty that the MOU will deliver the promised emission 

reductions. This AQMP seeks to provide the cleanest technologically feasible 

locomotives to accelerate emission reductions as early as possible. 

Recently, the U.S. EPA provided preliminary estimates of locomotive emissions of NOx 

and PM projected out to the year 2040. Figures 3-6A and 3-6B provide the emission 

projections from the various types of locomotives operating in the future. As older, 

uncontrolled locomotives (depicted in the figures as Uncontrolled and Tier 0 fleets) are 

turned over to newer, lower emission locomotives (depicted as Tier 1 and Tier 2 fleets), 

it is anticipated that the locomotive fleet will be cleaner in the future due to changes in 

the emission standards for new locomotives. Figures 3-6A and 3-6B show draft EPA 

model results for locomotives from 2006 to 2040 for NOx and PM, respectively. The 

national emission trends shown in these figures are similar to those for the South Coast 
Chapter 3 Base Year and Future Emissions 

3-21

Air Basin; that the anticipated growth will overtake the benefits of the cleaner Tier 2 

locomotives. 

 FIGURE 3-6A 

Projected Nationwide NOx Emissions from Locomotives 
Final 2007 AQMP 

3-22

Source: U.S. EPA, Presentation at the Second Public Meeting to Discuss Future Locomotive Emissions Control Factors, CARB (July 13, 2006). 

FIGURE 3-6B 

Projected Nationwide Particulate Matter Emissions from Locomotives 

TOP TEN SOURCE CATEGORIES (2002, 2014, 2023) 

This portion of Chapter 3 provides the ranking of the top 10 contributors to the 

inventory for the years 2002, 2014, and 2023. The annual average inventory for VOC, 

NOx, SOx and PM2.5 are shown in the following figures. VOC and NOx inventories 

are usually presented with a planning inventory, but the ranking would not change 

between planning and annual average. The categorization can be done several ways. 

These categories are fairly broad, intended for illustration purposes. 

Table 3-6 lists the top 10 categories for each of the three years for VOCs. The top five 

categories in each year are fairly consistent, although the ranking changes slightly for 

some categories. Mobile source categories and consumer products are responsible for a 

large portion of the emissions; the top 10 categories account for 82 percent of the total 

VOC inventory in 2002. 
Chapter 3 Base Year and Future Emissions 

3-23

TABLE 3–6 

Top Ten Ranking for VOC Emissions (2002, 2014, 2023), from Highest to Lowest 

 2002* 2014* 2023* 

1 Light-Duty Passenger Cars Consumer Products Consumer Products 

2 Consumer Products Off-Road Equipment Off-Road Equipment 

3 Off-Road Equipment Light-Duty Passenger Cars Recreational Boats 

4 Light-Duty Trucks Light-Duty Trucks Light-Duty Trucks 

5 Architectural Coatings Recreational Boats Petroleum Marketing 

6 Recreational Boats Petroleum Marketing Light Duty Passenger Cars 

7 Heavy-Duty Gasoline 

Trucks 

Architectural Coatings Architectural Coatings 

8 Medium-Duty Trucks Coatings & Related 

Processes 

Coatings & Related 

Processes 

9 Petroleum Marketing Medium-Duty Trucks Aircraft 

10 Coatings & Related 

Processes 

Heavy-Duty Gasoline 

Trucks 

Medium-Duty Trucks 

* Refer to Figures 3-7 to 3-18 for the annual average emissions totals. 
Final 2007 AQMP 

3-24

VOC Annual Average Emissions-2002 

35 31

25

28

44 49

91 99

110

178

0

40

80

120

160

200

Light-Duty Passenger Cars

Consumer Products

Off-Road Equipment

Light-Duty Trucks

Architectural Coatings

Recreational Boats

Heavy-Duty Gasoline Trucks

Medium-Duty Trucks

Petroleum Marketing

Coatings & Related Processes

FIGURE 3-7 

Top Ten Categories for VOC 2002 

VOC Annual Average Emissions-2014 

24 22 13 17

28 41 35

50

61

107

0

40

80

120

160

200

Consumer Products

Off-Road Equipment

Light-Duty Passenger Cars

Light-Duty Trucks

Recreational Boats

Petroleum Marketing

Architectural Coatings

Coatings & Related Processes

Medium-Duty Trucks

Heavy-Duty Gasoline Trucks

FIGURE 3-8 

Top Ten Categories for VOC 2014 
Chapter 3 Base Year and Future Emissions 

3-25

VOC Annual Average Emissions-2023 

27

24 13 13

31 29 31 35

50

114

0

40

80

120

160

200

Consumper Products

Off-Road Equipment

Recreational boats

Light-Duty Passenger Trucks

Petroleum Marketing

Light-Duty Passenger Cars

Architectural Coatings

Coatings & Related Processes

Aircraft

Medium-Duty Trucks

FIGURE 3-9 

Top Ten Categories for VOC 2023 

Table 3-7 shows the top 10 categories for each of the three years for NOx. As with their 

predominant contribution to VOC emissions, mobile source categories are the 

predominant contributor to NOx emissions. For NOx, RECLAIM and residential fuel 

combustion are the stationary and area source categories that are in the top 10 list. The 

top 10 categories account for 91 percent of the total NOx inventory in 2002. 
Final 2007 AQMP 

3-26

TABLE 3-7 

Top Ten Ranking for NOx Emissions (2002, 2014, 2023), from Highest to Lowest 

 2002* 2014* 2023* 

1 Off-Road Equipment Heavy-Duty Diesel Trucks Ships & Commercial 

Boats 

2 Heavy-Duty Diesel Trucks Off-Road Equipment Off-Road Equipment 

3 Light-Duty Passenger Cars Ships & Commercial 

Boats 

Heavy-Duty Diesel Trucks 

4 Light-Duty Trucks Light-Duty Trucks Aircraft 

5 Ships & Commercial 

Boats 

Light-Duty Passenger Cars Trains 

6 Medium-Duty Trucks RECLAIM RECLAIM 

7 Heavy-Duty Gasoline 

Trucks 

Heavy-Duty Gasoline 

Trucks 

Light-Duty Trucks 

8 Trains ** Trains ** Residential Fuel 

Combustion 

9 RECLAIM Residential Fuel 

Combustion 

Light-Duty Passenger Cars

10 Residential Fuel 

Combustion 

Aircraft Heavy-Duty Gasoline 

Trucks 

* Refer to Figures 3-7 to 3-18 for the annual average emissions totals. 

** This assumes that the CARB railroad MOU is fully effective. It is likely that this may not occur because there are 

broadly worded exemptions in the MOU that could result in less emission reductions. However, if AQMD Rules 3501 - 

Recordkeeping for Locomotive Idling and 3502 - Minimization of Emissions from Locomotive Idling are implemented, 

more certainty in achieving emission reductions will occur. Recently, these rules were held invalid by a court, if this 

decision is ultimately reversed and the rules are upheld, AQMD staff intends to submit these rules into the State 

Implementation Plan (SIP). 
Chapter 3 Base Year and Future Emissions 

3-27

NOx Annual Average Emissions-2002 

FIGURE 3-10 

Top Ten Categories for NOx 2002 

NOx Annual Average Emissions-2014

24 23 22 22

27 43 37

87

137 145

0

40

80

120

160

200

Heavy-Duty Diesel Trucks

Off-Road Equipment

Ships & Commercial Boats

Light-Duty Trucks

Light-Duty Passenger Cars

RECLAIM

Heavy-Duty Gasoline Trucks

Trains

Residential Fuel Combustion

Aircraft

FIGURE 3-11 

Top Ten Categories for NOx 2014 

38

242

228

148

127

64 52

29 27

48

0

50

100

150

200

250

300

Off-Road Equipment

Heavy-Duty Diesel Trucks

Light-Duty Passenger Cars

Light-Duty Trucks

Ships & Commercial Boast

Medium-Duty Trucks

Heavy-Duty Gasoline Trucks

Trains

RECLAIM

Residential Fuel Combustion
Final 2007 AQMP 

3-28

NOx Annual Average Emissions-2023

23 21 17 17 27

29 28

78 81

116

0

40

80

120

160

200

Ships & Commercial Boats

Off-Road Equipment

Heavy-Duty Diesel Trucks

Aircraft

Trains

RECLAIM

Light-Duty Trucks

Residential Fuel Combustion

Light-Duty Passenger Cars

Heavy-Duty Gasoline Trucks

FIGURE 3-12 

Top Ten Categories for NOx 2023 

Table 3-8 shows the top 10 categories for each of the three years for SOx. Ship 

emissions are a more significant contributor for SOx than for the other three pollutants 

in this section. RECLAIM is consistently the second by ranking. Ships and commercial 

boats are consistently the highest emitting source category. The top ten categories 

represent 95 percent of the total SOx inventory in 2002. 
Chapter 3 Base Year and Future Emissions 

3-29

TABLE 3-8 

Top Ten Ranking for SOx Emissions (2002, 2014, 2023), from Highest to Lowest 

 2002* 2014* 2023*

1 Ships & Commercial Boats Ships & Commercial Boats Ships & Commercial Boats 

2 RECLAIM RECLAIM RECLAIM 

3 Petroleum Refineries (nonRECLAIM) Aircraft Aircraft 

4 Heavy-Duty Diesel Trucks Manufacturing & Industrial 

Combustion 

Manufacturing & Industrial 

Combustion 

5 Aircraft Light-Duty Passenger Cars Light-Duty Passenger Cars 

6 Trains ** Light-Duty Trucks Light-Duty Trucks 

7 Off-Road Equipment Service & Commercial 

Combustion 

Service & Commercial 

Combustion 

8 Light-Duty Passenger Cars Petroleum Refineries (nonRECLAIM) Petroleum Refineries (nonRECLAIM) 

9 Manufacturing & Industrial 

Combustion 

Waste Burning & Disposal Waste Burning & Disposal 

10 Light-Duty Trucks Residential Fuel 

Combustion 

Residential Fuel 

Combustion 

* Refer to Figures 3-7 to 3-18 for the annual average emissions totals. 

** This assumes that the CARB railroad MOU is fully effective. It is likely that this may not occur because there are 

broadly worded exemptions in the MOU that could result in less emission reductions. However, if AQMD Rules 

3501 - Recordkeeping for Locomotive Idling and 3502 - Minimization of Emissions from Locomotive Idling are 

implemented, more certainty in achieving emission reductions will occur. Recently, these rules were held invalid by 

a court. If this decision is ultimately reversed, and the rules are upheld, AQMD staff intends to submit these rules into 

the State implementation Plan (SIP). 
Final 2007 AQMP 

3-30

SOx Annual Average Emissions-2002

23

12

7

2 111111

0

5

10

15

20

25

30

Ships & Commercial Boats

RECLAIM

Petroleum Refineries

Heavy-Duty Diesel Trucks

Aircraft

Trains

Off-Road Equipment

Light-Duty Passenger Cars

Manufacturing & Industrial Combustion

Light-Duty Trucks

tpd

FIGURE 3-13 

Top Ten Categories for SOx 2002 

SOx Annual Average Emissions-2014

22

12

2 11111 0.5 0.5

0

5

10

15

20

25

30

Ships & Commercial Boats

RECLAIM

Aircraft

Manufacturing & Industrial Combustion

Light-Duty Passenger Cars

Light-Duty Trucks

Service & Commercial Combustion

Petroleum Refineries

Waste Burning & Disposal

Residential Fuel Combustion

tpd

FIGURE 3-14 

Top Ten Categories for SOx 2014 
Chapter 3 Base Year and Future Emissions 

3-31

FIGURE 3-15 

Top Ten Categories for SOx 2023 

Table 3-9 shows the top 10 categories for each of the three years for directly emitted 

PM2.5. In contrast to the rankings for the other three pollutants in this section of the 

chapter, paved road dust and cooking are consistently at the top of the ranking for 

PM2.5 emissions. Each of these categories increases over time. The top ten categories 

represent 80 percent of the total directly emitted PM2.5 inventory in 2002, however, 

total directly emitted PM2.5 only accounts for about 25 percent of all ambient PM2.5. 

SOx Annual Average Emissions-2023 

33

12

3 2 1111 0.5 0.5

0

5

10

15

20

25

30

35

40

Ships & Commercial Boats

RECLAIM

Aircraft

Manufacturing & Industrial Combustion

Light-Duty Passenger Cars

Light-Duty Trucks

Service & Commercial Combustion

Petroleum Refineries

Waste Burning & Disposal

Residential Fuel Combustion

tpd
Final 2007 AQMP 

3-32

TABLE 3-9 

Top Ten Ranking for Directly Emitted PM2.5 Emissions (2002, 2014, 2023), 

from Highest to Lowest 

 2002* 2014* 2023* 

1 Paved Road Dust Paved Road Dust Paved Road Dust 

2 Commercial Cooking Commercial Cooking Commercial Cooking 

3 Off-Road Equipment Residential Fuel Combustion Residential Fuel Combustion 

4 Heavy-Duty Diesel Trucks Off-Road Equipment Construction & Demolition 

Dust 

5 Residential Fuel 

Combustion 

Construction & Demolition 

Dust 

Ships and Commercial Boats 

6 Ships & Commercial Boats Heavy-Duty Diesel Trucks Light-Duty Trucks 

7 Light-Duty Passenger Cars Waste Burning & Disposal Light-Duty Passenger Cars 

8 Construction & Demolition 

Dust 

Light-Duty Trucks Waste Burning & Disposal 

9 Light-Duty Trucks Light-Duty Passenger Cars Recreational Boats 

10 Wood & Paper Ships & Commercial Boats Off-Road Equipment 

* Refer to Figures 3-7 through 3-18 for the annual average emissions totals. 

Directly Emitted PM2.5

Annual Average Emissions-2002

19

13 13

9 8

444 3 2

0

5

10

15

20

25

Paved Road Dust

Commercial Cooking

Off-Road Equipment

Heavy-Duty Diesel Trucks

Residential Fuel Combustion

Ships & Commercial Boats

Light-Duty Passenger Cars

Construction & Demolition Dust

Light-Duty Trucks

Wood & Paper

tpd

FIGURE 3-16 

Top Ten Categories for PM2.5 2002 
Chapter 3 Base Year and Future Emissions 

3-33

Directly Emitted PM2.5

Annual Average Emissions-2014

19

15

9

7 6 6 5 444

0

5

10

15

20

25

Paved Road Dust

Commercial Cooking

Residential Fuel Combustion

Off-Road Equipment

Construction & Demolition Dust

Heavy-Duty Diesel Trucks

Waste Burning & Disposal

Light-Duty Trucks

Light-Duty Passenger Cars

Ships & Commercial Boats

tpd

FIGURE 3-17 

Top Ten Categories for PM2.5 2014 

FIGURE 3-18 

Top Ten Categories for PM2.5 2023 

Directly Emitted PM2.5 

Annual Average Emissions-2023 

20

16

9

7 6 5555

3

0

5

10

15

20

25

Paved Road Dust

Commercial Cooking

Residential Fuel Combustion

Construction & Demolition Dust

Ships & Commercial Boats

Light-Duty Trucks

Light-Duty Passenger Cars

Waste Burning & Disposal

Recreational Boats

Off-Road Equipment

tpd