Chapter 3 - Emission Inventory
❖
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3 EMISSIONS INVENTORY 

3.1 INTRODUCTION 

This chapter discusses the emissions inventory (EI) as related to ozone 

attainment demonstrations for the SJVAB. The two principal components of 

OADP EIs are a baseline year and future year projections. The projections 

reflect emissions reductions stemming from implementation of controls as well as 

emissions increases stemming from growth. Future year emissions are used as 

input to a grid-based photochemical computer model that simulates physical and 

chemical processes in the atmosphere and predicts future ozone levels. 

Comparison of the magnitude and frequency of the predicted future ozone levels 

with the national ambient air quality standards allows a demonstration of 

attainment from the emission controls. The baseline year and future year EIs 

were developed to reflect emissions of volatile organic compounds (VOCs) and 

nitrogen oxides (NOx) during the ozone season (May through October). Ozone 

is not emitted directly into the atmosphere, and thus it does not appear in an 

emissions inventory. Ozone is created through a photochemical reaction 

between VOCs and NOx in the presence of sunlight. NOx and VOCs, which are 

termed ozone precursors, are directly emitted and can be measured as emitted 

or estimated using parameters that can be easily measured; therefore, they are 

included in the EI. The EI identifies the sources and quantities of these 

precursors. VOC emissions from society’s activities generally result from 

evaporation of liquids, release of gaseous VOCs, and incomplete combustion. 

NOx emissions are primarily the result of high temperature combustion. 

Section 3.2 describes the types of emission inventories, Section 3.3 describes 

the baseline year inventory, and Section 3.4 describes development of the future 

year inventory. Section 3.5 discusses conformity, and Section 3.6 discusses 

emission inventory uncertainties. Conclusions are presented in Section 3.7. 

3.2 INVENTORY TYPES 

An EI is a compilation of emission sources and corresponding quantities of air 

pollutants emitted per unit time (e.g., tons/day) for a specified time period (e.g., 

1990, ozone season 2002, etc.). The two basic types of EIs are modeling and 

planning inventories; each has a different purpose in the overall air quality 

planning process, and each reflects a different compilation of emission sources. 

3.2.1 Modeling Inventory 

The modeling inventory typically represents emissions that occurred on specific 

days when ambient ozone levels exceeded the NAAQS at locations within the 

SJVAB. Modeling inventories are used to help understand the conditions that 

create the high ozone levels and to evaluate emission control measures needed 
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to attain the ozone NAAQS. Modeling EIs therefore include all sources of VOCs 

and NOx that could be contributing to the problem: anthropogenic (caused by 

human activity), biogenic (e.g., caused by plants, molds, and animals) and 

geogenic (e.g., caused by earth processes such as oil seeps). Biogenic and 

geogenic sources can emit significant quantities of pollutants. Modeling 

inventories, meteorological conditions, and emission control effectiveness are all 

used as input to photochemical models to demonstrate that implementation of 

specified emission control programs will result in attainment of the ozone 

NAAQS. Also, the spatial coverage of modeling inventories extends beyond the 

SJVAB boundaries to capture transport and other processes affecting high ozone 

levels on specific days. 

EIs used in the District’s attainment demonstration plans are based on data 

contained in the ARB’s California Emission Inventory Development and 

Reporting Air System (CEIDARS), the California Emission Forecasting System 

(CEFS), and the Central California Ozone Study (CCOS). The emissions 

inventory used for model calibration is “day specific.” It represents the emissions 

that occurred when the federal standard for ozone was exceeded in the SJVAB. 

The use of day specific emissions allows model results to be compared to and 

calibrated with measured ozone levels. 

Modeling inventories encompass an area larger than the SJVAB. The modeling 

domain is divided into a grid system composed of 4 Km by 4 Km grid cells 

defined by Universal Transverse Mercator (UTM) coordinates (see Chapter 5). 

Modelers allocate stationary and mobile source emissions to individual grid cells 

within this system. They locate area source emissions using readily measured 

parameters whose behavior would correlate with emissions (e.g., population 

density). In general, the modeling emission data features episodic-day emissions 

for the base year. 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. Finally emissions 

used for modeling are assigned to chemical classes depending on their reactivity 

in producing ozone in the atmosphere. Hence, “gridded” emissions data used for 

ozone modeling applications differ from the average annual day or planning 

inventory emission data in two respects: 1) the modeling region covers larger 

geographic areas than the SJVAB; and 2) emissions represent day-specific 

estimates instead of average or seasonal conditions for the base year. 

For seasonal sources, emissions were determined by calculating the number of 

operating days in 1999 during the ozone season and dividing the total emissions 

for the season by the number of days that the activity occurred during the 

season. For non-seasonal point sources, emissions for an average operating 

day were calculated by dividing the facility’s total emissions for 1999 by the 

number of operating days throughout 1999 that the facility operated. 
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Unlike area and point sources, the motor vehicle emissions inventory was 

temperature adjusted to represent a typical “summertime” day. Emissions 

factors for motor vehicles reflect temperature and activity data (vehicle miles 

traveled, speed, etc.) for six daily time periods. The emissions accounted for in 

the District’s planning inventories are based on the California mobile emission 

model EMFAC2002. 

3.2.2 Planning Inventory 

The planning inventory represents a “typical” summer day during the seasonal 

time period in which ambient air quality standards are violated. For example, the 

ozone planning inventory is based on daily emissions that occurred during the 

ozone season, May through October. Although the modeling and planning 

inventories are based on the same data, the planning inventory is better suited 

for summary representation of emissions and for fulfilling regulatory 

requirements. The planning inventory is geared towards complying with 

emission reduction requirements and the role of control measures in meeting 

those requirements; it therefore includes only anthropogenic emission sources 

and does not include biogenic or geogenic emissions. The planning inventory 

also only includes sources within the SJVAB boundaries. 

3.2.3 Data Sources and Accuracy 

The bulk of the SJVAB EI is actually estimated rather than directly measured. 

Multiplying an emission factor by an activity level produces an estimated 

emission; if the source has a pollutant control device or technique applied, 

emission estimates are reduced to reflect the efficiency of the pollution control. 

Emission factors relate air pollutant emission rates (usually mass per unit time) to 

an easy-to-measure activity level for various types of sources (typically the 

factors are available for major air pollutant sources found in many regions and 

states). For example, emission factors for engine operation may use horsepower 

or gallons of fuel consumed to determine emissions. The emission estimates for 

most point sources (specific facilities) are more reliable than the estimates for 

generic classes of sources because emissions from point sources are usually 

tested, and the test results are used to generate the emission factors. 

Furthermore, facility operators can inform the District of their actual production 

figures or fuel burned, thereby eliminating the need for the District to estimate 

this type of data. In addition, some major sources are equipped with automated 

emissions monitoring equipment that directly measures emissions to the 

atmosphere and eliminates the needs for estimations. 

Estimating area source emissions is more difficult. Point source estimating 

techniques are often used, but with less reliability. For example, determining the 

amounts of specific consumer products used within the SJVAB entails making 

estimates and assumptions and consulting a variety of data sources that might 

describe an easily-measured parameter (such as regional sales for a class of 
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product) but do not provide needed information such as location and quantity of 

use of individual products. Consequently, the resultant quality of the data is not 

as good as data from point sources and point source tests. Area source 

emissions estimates often are based on total activity during a season and do not 

provide much information about typical use, daily activity, or exact location of the 

source. 

Because of the variety of data used to compile EIs and the calculations 

performed on these data, emissions estimates vary in their accuracy. For 

example, emissions directly measured by a continuous emissions monitor are 

generally more accurate than emissions estimated from activity levels, emission 

factors and control efficiencies. Emissions data in this OADP are reported to the 

nearest 0.1 tons (200 lbs)/day (with one or two exceptions), even though this 

level of accuracy may not be representative of all of the inventory source types. 

3.2.4 Emission Source Types 

3.2.4.1 Stationary Sources 

Theoretically, stationary sources are divided into two major subcategories: point 

and area sources. However, for EI purposes, only point sources are categorized 

as stationary sources. Point sources are generally large emitters with one or 

more emissions points at a permitted facility with an identified location. 

Examples include food processing facilities, oil production and refinery facilities, 

steam generators, boilers, process heaters, stationary piston engines, glass 

manufacturing, and mining operations. The emissions from point sources are 

generally calculated using emission factors obtained from direct measurements 

(e.g., source testing), EPA’s document entitled, Compilation of Air Pollutant 

Emissions Factors (AP-42), or ARB’s material balance formula. The simplest 

method of calculating emissions is to multiply the process rate (how much or how 

often an activity occurs) by an emissions factor (mass of air pollutant emitted per 

unit time of activity) and a control factor (percent of emissions not allowed to 

reach the atmosphere). For most point sources, facility operators provide the 

process rates (activity levels) that are necessary for emission calculations. Some 

point sources are equipped with continuous emissions monitoring equipment that 

provides direct measurement of selected pollutants as they are emitted from a 

stack to the atmosphere. For these sources, emissions are directly measured 

and need not be estimated using emission factors and activity levels. 

3.2.4.2 Area Sources 

ARB and the District jointly develop the area source emission inventories, with 

the ARB responsible for about two-thirds of the sources and the District for the 

remaining one-third. Area source categories are divided into two types: 

aggregated point and area-wide. Aggregated point sources are many small point 

sources, or facilities, that are not inventoried individually, but are estimated as a 

group and reported as a single source category. Examples of aggregated point 
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sources include residential water heaters, dry cleaning operations, and 

automobile service stations. Area-wide sources include many dispersed sources 

that emit pollutants over a broad geographic area and are not reported in the 

stationary source inventory. Examples of area-wide sources include consumer 

products (e.g., nail polish, hair spray, aftershave, household cleaners, paints, 

windshield washer fluid); home-use pesticides; asphalt paving; pavementmarking paints; off-gassing of manufactured products; residential fuel 

combustion; farming operations; construction and demolition; road dust; fires; 

waste burning; and utility equipment. 

3.2.4.3 Mobile Sources 

ARB develops on-road and non-road mobile source emissions estimates, and 

maintains a comprehensive compilation of emission factors. These factors are 

combined with appropriate activity levels and estimates of control measure 

effectiveness to calculate the emissions (the computer tool used to calculate 

mobile emissions is referred to as “EMFAC”, although the term “EMFAC” is often 

used to also describe the final calculated emission estimates). As ARB releases 

new versions of EMFAC, they are named with the year of release and usually 

version number within a given year (e.g., EMFAC2002, v. 2.2). 

The mobile source category “on-road motor vehicles” includes light duty 

passenger vehicles, light- and medium-duty trucks, heavy-duty trucks (gas and 

diesel), heavy-duty urban buses (diesel) and motorcycles. Motor vehicle 

emissions occur both through the exhaust pipe and from fuel evaporation. ARB 

uses a complex methodology to calculate the number of motor vehicles, their age 

and speed distribution, and the resulting emissions of NOx, total organic gases 

(TOG), reactive organic gases (ROG), carbon monoxide (CO), sulfur oxides 

(SOx), and particulate matter (PM10). ARB uses EMFAC to develop on-road 

motor vehicle emission estimates using estimated vehicle miles traveled. 

Non-road mobile sources include off-road vehicles such as construction 

equipment, farm tractors, trains, ships, aircraft (both government, commercial, 

and private), mobile equipment (forklifts, etc.), and utility equipment (lawn and 

garden equipment and chain saws). 

3.2.4.4 Natural Sources 

In addition to man-made air pollution, there are natural sources of emissions, 

also known as biogenic sources (i.e., plants, molds, and animals,) and geogenic 

sources (such as oil seeps and other earth processes). These natural sources 

emit significant quantities of pollutants. For example, certain types of vegetation 

emit large amounts of isoprene, terpenes, and other organic compounds that are 

VOC. Emission rates depend upon plant species, season, biomass density, time 

of day, local temperature, moisture, and other factors. 
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The SJVAB biogenic VOC emissions inventory, currently estimated at 380 tons 

per day, has been the subject of recent research and refinements. Seasonal or 

annual estimates have not been prepared using this updated methodology, but it 

provides a sense of the magnitude of biogenic emissions during the summer. 

3.3 BASELINE YEAR EMISSIONS 

The District and ARB developed a well-characterized emissions inventory for 

1999 and projected it to years of interest given information on growth trends and 

control measures that occurred in specific source categories over the time 

periods of interest. SJVAB emissions for 2000 establish a baseline for evaluating 

trends out to selected future years (Table 3-1).1

 Carbon monoxide (CO) is 

included in Table 3-1 because CO can help produce ozone (though it is not 

typically described as an ozone precursor). The CO emissions in Table 3-1 do 

not set an emissions budget for conformity (the SJVAB is no longer 

nonattainment for CO). 

Planners calculate the seasonal point source emissions in the EI by applying the 

fractional monthly throughputs during the ozone season and then dividing the 

total emissions by the number of days that the activity occurred during the 

season. Planners calculate non-seasonal point source emissions (average 

operating day) by dividing the facility’s total emissions for a given year by the 

number of days per year of interest that the facility operated. 

Unlike area and point sources, the motor vehicle emissions inventory was 

temperature adjusted to represent a typical “summertime” day. Emission factors 

for motor vehicles reflect temperature and activity data (vehicle miles traveled, 

speed, etc.) for six daily time periods. EMFAC2002, Version 2.2 was used in this 

document to compute on-road motor vehicle emissions in the planning 

inventories. Table 3-1 includes the EMFAC2002, Version 2.2 results. 

Table 3-1 presents the planning EI for 2000 as well as for 2008 and 2010 (2008 

is a Rate of Progress milestone year and 2010 is the target attainment year; note 

that ROP uses 1990 as a baseline—see Chapter 7). Summer 2000 emissions 

represent the overall magnitude of emissions that led to the ozone levels 

occurring during the CCOS episode (see Section 2.4.2.3) used in this Extreme 

OADP.

2

 Appendix A presents the county-by-county 2008 and 2010 planning onroad motor vehicle emissions inventories, of which VOC and NOx emissions form 

the basis of conformity budgets developed later in this chapter. 

 

1

 Note that different baselines are used in this plan for different purposes. Chapter 7 uses 1990 

as a baseline for Rate of Progress calculations as required by the Federal Clean Air Act. Chapter 

5 uses day-specific emissions from the July/August 2000 CCOS episode as a base case to 

establish model performance. 

2

 As discussed in Section 3.2.1, the modeling inventory gives day-specific emissions by grid cell 

in the SJVAB and by reactivity class for VOC; because of its complexity and volume, it is not 

suitable for reproduction or inclusion in this Extreme OADP in either tabular or text form. 
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Table 3-1 

SJVAB 2000, 2008 and 2010 Planning Emissions Inventories

(Summer, tons/day, 1999 Base Year) 

Source Categories 20001

VOC 

2008 

VOC 

2010 

VOC 

20001

CO 

2008 

CO 

2010 

CO 

20001

NOx 

2008 

NOx 

2010 

NOx 

STATIONARY SOURCES: FUEL COMBUSTION 

Electric Utilities 0.4 0.5 0.5 2.4 2.7 2.8 3.1 3.0 3.1 

Cogeneration 0.8 0.9 1.0 7.0 9.3 9.6 9.0 6.1 6.3 

Oil and Gas 

Production 

(Combustion) 

2.7 3.2 3.2 14.4 15.9 15.7 39.6 25.9 25.4 

Petroleum Refining 

(Combustion) 0.1 0.1 0.1 0.4 0.4 0.4 1.5 1.5 1.5 

Manufacturing and 

Industrial 0.3 0.4 0.4 5.7 6.7 6.8 36.5 38.7 39.7 

Food and 

Agricultural 

Processing 

2.7 2.6 2.6 11.1 10.9 10.9 26.9 24.5 23.6 

Service and 

Commercial 1.2 1.3 1.3 3.3 3.4 3.5 13.7 14.2 14.4 

Other (Fuel 

Combustion) 0.2 0.1 1.1 0.7 0.5 0.4 1.8 1.4 1.2 

TOTAL FUEL 

COMBUSTION 8.4 9.1 10.2 45.0 49.8 50.1 132.1 115.3 115.3 

STATIONARY SOURCES: WASTE DISPOSAL 

Sewage Treatment 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 

Landfills 2.8 3.3 3.4 0.0 0.0 0.0 0.0 0.0 0.0 

Incinerators 0.0 0.0 0.0 0.0 0.1 0.1 0.1 0.1 0.1 

Soil Remediation 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 

Other 0.5 0.6 0.6 0.0 0.0 0.0 0.0 0.0 0.0 

TOTAL WASTE 

DISPOSAL 3.3 3.9 4.0 0.0 0.1 0.1 0.1 0.1 0.1 

STATIONARY SOURCES: CLEANING AND SURFACE COATING 

Laundering 0.1 0.1 0.1 0.0 0.0 0.0 0.0 0.0 0.0 

Degreasing 11.1 1.5 1.5 0.0 0.0 0.0 0.0 0.0 0.0 

Coatings & Related 

Process Solvents 13.8 16.5 17.5 0.0 0.0 0.0 0.0 0.0 0.0 

Printing 1.5 1.6 1.7 0.0 0.0 0.0 0.0 0.0 0.0 

Adhesives and 

Sealants 0.7 0.6 0.6 0.0 0.0 0.0 0.0 0.0 0.0 

Other 2.8 3.8 4.0 0.0 0.0 0.0 0.0 0.0 0.0 

TOTAL CLEANING 

AND SURFACE 

COATINGS 

29.9 24.1 25.4 0.0 0.0 0.0 0.0 0.0 0.0 

 
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Table 3-1: SJVAB 2000, 2008 and 2010 Planning Emissions Inventories- 

(cont.)

Source Categories 20001

VOC 

2008 

VOC 

2010 

VOC 

20001

CO 

2008 

CO 

2010 

CO 

20001

NOx 

2008 

NOx 

2010 

NOx 

STATIONARY SOURCES: PETROLEUM PRODUCTION AND MARKETING 

Oil & Gas 

Production 31.6 32.1 31.4 0.1 0.1 0.12 0.2 0.2 0.2 

Petroleum Refining 1.4 1.4 1.4 0.2 0.2 0.2 0.1 0.1 0.1 

Petroleum 

Marketing 6.6 7.1 7.3 0.0 0.1 0.1 0.0 0.0 0.0 

Other (Petroleum 

Production and 

Marketing) 

0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 

TOTAL 

PETROLEUM 

PROD./MKTG. 

39.6 40.6 40.1 0.4 0.4 0.4 0.3 0.3 0.3 

STATIONARY SOURCES: INDUSTRIAL PROCESSES 

Chemical 1.9 2.4 2.5 0.0 0.0 0.0 0.1 0.1 0.2 

Food/Agricultural 10.7 11.5 11.8 2.2 2.1 2.1 9.2 9.0 9.0 

Mineral Processes 0.3 0.4 0.4 0.4 0.4 0.4 1.5 1.7 1.7 

Metal Processes 0.2 0.2 0.2 0.1 0.1 0.1 0.0 0.0 0.0 

Wood and Paper 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 

Glass and Related 

Products 0.1 0.1 0.1 0.3 0.3 0.3 12.0 9.6 10.1 

Electronics 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 

Other (Industrial 

Processes) 0.1 0.1 0.2 0.0 0.0 0.0 0.0 0.0 0.0 

TOTALINDUSTRIAL 

PROCESSES 

13.3 14.6 15.1 2.9 2.9 3.0 22.9 20.5 21.0 

TOTAL 

STATIONARY 

SOURCES 

94.3 92.3 94.6 48.1 53.1 53.5 155.2 136.2 136.6 
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Table 3-1: SJVAB 2000, 2008 and 2010 Planning Emissions Inventories- 

(cont.)

Source Categories 20001

VOC 

2008 

VOC 

2010 

VOC 

20001

CO 

2008 

CO 

2010 

CO 

20001

NOx 

2008 

NOx 

2010 

NOx 

AREA SOURCES: SOLVENT EVAPORATION 

Consumer Products 25.2 25.7 26.7 0.0 0.0 0.0 0.0 0.0 0.0 

Architectural 

Coatings and 

Related Process 

Solvents 

14.1 12.9 13.1 0.0 0.0 0.0 0.0 0.0 0.0 

Pesticides/Fertilizers 27.8 24.0 23.4 0.0 0.0 0.0 0.0 0.0 0.0 

Asphalt 

Paving/Roofing 2.8 3.0 3.0 0.0 0.0 0.0 0.0 0.0 0.0 

TOTAL SOLVENT 

EVAPORATION 70.0 65.6 66.3 0.0 0.0 0.0 0.0 0.0 0.0 

AREA SOURCES: MISCELLANEOUS PROCESSES 

Residential Fuel 

Combustion 0.5 0.5 0.5 5.4 5.6 5.6 3.3 3.0 3.0 

Farming Operations 59.8 68.8 71.0 0.0 0.0 0.0 0.0 0.0 0.0 

Construction and 

Demolition 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 

Paved Road Dust 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 

Unpaved Road Dust 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 

Fugitive Windblown 

Dust 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 

Fires 0.1 0.1 0.1 1.2 1.3 1.3 0.0 0.0 0.0 

Waste Burning and 

Disposal 33.8 32.8 32.6 423.1 414.1 412.2 2.9 2.9 2.8 

Cooking 0.4 0.5 0.50 0.0 0.0 0.0 0.0 0.0 0.0 

Other (Misc.) 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 0.0 

TOTAL 

MISCELLANEOUS 

PROCESSES 

94.6 102.7 104.7 429.6 420.9 419.1 6.2 5.9 5.8 

TOTAL AREA 

SOURCES 164.6 168.3 171.1 429.6 420.9 419.1 6.3 5.9 5.9 
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Table 3-1: SJVAB 2000, 2008 and 2010 Planning Emissions Inventories- 

(cont.)

Source Categories 20001

VOC 

2008 

VOC 

2010 

VOC 

20001

CO 

2008 

CO 

2010 

CO 

20001

NOx 

2008 

NOx 

2010 

NOx 

MOBILE SOURCES: ON-ROAD MOTOR VEHICLES 4

Light Duty 

Passenger (LDA) 47.2 23.0 19.2 459.1 240.3 202.5 40.6 19.4 16.1 

Light Duty Trucks-1 

(LDT1) 23.7 14.5 12.5 291.0 163.7 138.6 24.9 13.1 11.0 

Light Duly trucks-2 

(LDT2) 15.7 10.4 9.4 195.5 117.4 103.5 21.4 12.6 11.0 

Medium Duty Trucks 6.8 4.5 4.1 82.8 51.0 45.7 10.3 6.4 5.6 

Light Heavy Duty 

Gas Trucks-1 

(LHDV1) 

4.7 1.5 1.4 34.1 8.4 7.0 2.3 2.3 2.4 

Light Heavy Duty 

Gas Trucks-2 

(LHDV2) 

0.6 0.5 0.5 5.4 2.9 2.5 0.7 0.7 0.7 

Medium Heavy Duty 

Gas Trucks (MHDV) 4.4 2.7 2.4 39.2 19.9 16.7 2.7 2.1 1.9 

Heavy Heavy Duty 

Gas Trucks (HHDV) 2.4 1.6 1.4 42.6 21.1 17.8 4.4 2.8 2.4 

Light Heavy Duty 

Diesel Trucks-1 

(LHDV1) 

0.1 0.2 0.2 0.3 0.7 0.7 2.0 2.4 2.1 

Light Heavy Duty 

Diesel Trucks-2 

(LHDV2) 

0.2 0.2 0.2 0.4 0.5 0.5 2.2 1.8 1.6 

Medium Heavy Duty 

Diesel Trucks 

(MHDV) 

0.6 0.6 0.6 3.8 4.1 4.0 18.0 15.9 14.1 

Heavy Heavy Duty 

Diesel Trucks 

(MHDV) 

4.2 3.7 3.4 18.4 15.3 14.2 85.4 69.6 60.9 

Motorcycles 2.3 2.0 1.9 16.0 18.3 16.4 0.4 0.5 0.5 

Heavy Duty Urban 

Diesel Buses (UB) 0.2 0.2 0.2 0.7 0.7 0.7 3.6 3.5 3.5 

Heavy Duty Gas 

Urban Buses (UB) 1.0 1.1 1.1 11.5 9.9 9.6 0.9 1.0 1.0 

School Buses 0.3 0.3 0.3 4.9 3.3 3.2 2.1 2.6 2.6 

Motor Homes 0.9 0.8 0.7 25.1 18.3 15.7 1.9 1.8 1.7 

TOTAL ON-ROAD 

MOTOR VEHICLES 115.3 67.8 59.5 1230.8 695.8 599.3 223.8 158.5 139.1 
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Table 3-1: SJVAB 2000, 2008 and 2010 Planning Emissions Inventories- 

(cont.)

Source Categories 20001

VOC 

2008 

VOC 

2010 

VOC 

20001

CO 

2008 

CO 

2010 

CO 

20001

NOx 

2008 

NOx 

2010 

NOx 

OTHER MOBILE SOURCES 

Aircraft 6.9 7.2 7.3 63.6 71.4 72.7 2.3 2.4 4.03

Trains 1.2 1.2 1.1 4.3 4.8 5.0 32.6 21.3 20.8 

Ships and 

Commercial Boats 0.1 0.1 0.1 0.2 0.2 0.2 0.3 0.3 0.3 

Recreational Boats 18.6 12.5 10.4 108.5 98.5 98.0 3.7 5.3 5.3 

Off-Road 

Recreational Vehicle 1.8 1.1 1.1 15.9 16.4 16.9 0.3 0.3 0.3 

Off-Road Equipment 20.2 12.8 11.7 6 165.9 132.2 127.5 51.5 39.6 34.9 6

Farm Equipment 12.4 9.2 8.3 72.6 61.5 60.0 80.9 59.1 54.5 

Fuel Store/Handle 8.0 2.4 2.4 0.0 0.0 0.0 0.0 0.0 0.0 

TOTAL OTHER 

MOBILE SOURCES 69.2 46.5 42.4 430.9 385.0 380.2 171.5 128.4 120.13

TOTAL MOBILE 

SOURCES 184.5 114.3 101.9 1661.7 1080.8 879.5 395.3 287.0 259.23

TOTAL 

SAN JOAQUIN 

VALLEY 

443.5 374.9 367.6 2139.4 1554.8 1352.1 556.8 429.1 401.7 

1 Emissions data for all source categories came from the ARB emissions inventory spreadsheet 

prepared by the California Air Resources Board for the San Joaquin Valley, v2.11_RF932PEI as 

accessed from the Central California Ozone Study website in January 2004. This inventory 

reflects control measures in place as of September 2002. Adjustments as noted below. 

2 An entry of “0.0” means that emissions data are available but are equal to or less than 0.04 

tons/day, and thus have been rounded to 0.0 in accordance with the rounding protocol described 

in Appendix A. Totals of columns may not match sum of entries due to rounding. 

3

 Includes line item increase of 1.5 tpd for increased aircraft operations at Lemoore Naval Air 

Station (2010 NOx only). 

4 For the purposes of consistency, the on-road motor vehicle emissions inventory from the 

January 2004 CCOS inventory was replaced with the actual emissions data used in deriving the 

2008 and 2010 conformity budgets presented later in this Chapter (Table 3-4). 

5

 VOC and NOx emissions in 2010 were increased by 1.0 tpd VOC and 0.1 tpd NOx to account 

for ARB lawn and garden equipment control measures whose emissions reductions were 

inadvertently reflected in the planning inventory before ARB adopted the Statewide Strategy. 6

 VOC and NOx emissions in 2010 were increased by 0.04 tpd VOC and 0.1 tpd NOx to account 

for an adopted ARB control measure for stationary internal combustion engines whose emission 

reductions were inadvertently reflected in the planning inventory prior to adoption of the measure. 
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3-12 

3.4 FUTURE INVENTORIES

Demonstrating attainment of ambient air quality standards at a future date 

requires development of future year inventories that are based on assumptions of 

current levels of controls on sources, growth in activity in the District, use of 

emission reduction credits (ERCs), and implementation of future programs that 

affect emissions of air pollutants. These factors are discussed in the following 

subsections. Table 3-1 summarizes the 2008 and 2010 emission inventories. 

3.4.1 Growth Factors 

Changes in the baseline emissions inventory over time result from emissions 

growth (or decline) and/or emissions control. Predicting future ozone precursor 

emission rates is traditionally accomplished by assuming that VOC and NOx 

emissions are directly related to social and economic activities and control levels. 

If social and economic activity levels increase, it is generally assumed that 

emissions will similarly increase. Indicators representing social and economic 

activity levels include population, housing, employment, barrels of oil produced, 

cubic feet of natural gas produced, and vehicle miles traveled. These indicators 

are referred to as “surrogates.” The ratio of the projected surrogate each year to 

the actual 1999 level of activity for each surrogate is referred to as its growth 

factor. Growth factors are multiplied by 1999 emissions to project future year 

emissions. A growth factor of less than one indicates a decline in an activity over 

the planning period, while a growth factor of more than one indicates an increase 

in activity. 

ARB and the District compiled growth factor estimates for the years 2008 and 

2010 for each of the eight counties within the District using the best data 

available. Although using growth factors is a standard method for projecting 

emissions, their use cannot account for all activities that might occur in an area 

during a given time frame. Moreover, they tend to be more accurate when 

applied to the Valley as a whole, rather than on a county-by-county basis. For 

example, one facility might gain in market share while another loses its market 

share even though production increases at both facilities. While the overall 

growth factor is correct, each facility had very different growth rates. 

On-road mobile source emissions growth is estimated for each class of vehicle 

by ARB based on estimates of vehicle miles traveled provided by Regional 

Transportation Planning Agencies (RTPAs) located within the District, and 

Caltrans. ARB then disaggregates this information by vehicle class and 

estimates on-road mobile source emissions using the most current version of 

EMFAC. Also, enhanced inspection and maintenance programs for motor 

vehicles are factored into the mobile source projections. These data collectively 

represent the best available estimates on a county-by-county basis of future 

activity level for stationary and mobile sources within the District. 
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3.4.2 Control Factors 

After the baseline EI is multiplied by a growth factor, it is then multiplied by a 

control factor. A control factor is a weighted average that represents the level of 

controls of one or more rules and regulations and/or programs for a group of 

sources. This control factor takes into account information other than control 

levels stated in a rule or program. Rule penetration, compliance rates, public 

awareness, and participation are considered in determining a control factor. 

Control factors need to be updated on a continuing basis as the production 

levels, industry types and size, programs, public awareness, and other conditions 

change over time. The District and ARB compiled control factor estimates using 

the best data available for each of the eight counties in the SJVAB, based on rule 

adoption schedules and program changes stated in this and other plans. 

3.4.3 Inclusion of Emission Reduction Credits (ERCS) 

3.4.3.1 Introduction 

The District requires all new and modified stationary sources that increase 

emissions in amounts in excess of emission offset thresholds to obtain emission 

reduction credits (ERCs) to offset the growth in emissions. District Rule 2201 

(New and Modified Stationary Source Review Rule) contains the offset 

requirement. Offsets represent either on-site reductions or the use of banked 

ERCs. The District expects that some pre-baseline (pre-2000 for this Extreme 

OADP) credits will be used to allow growth from permitted stationary sources. 

Appendix B presents the current list of ERCs for the SJVAB for NOx and VOC. 

The General Preamble to the Federal Clean Air Act (57 FR 13498) states that 

“the pre-baseline ERCs must be reflected as growth and included in the 

attainment demonstration “to the extent that the State expects that such credits 

will be used as offsets or netting prior to attainment of the ambient standards.” 

The August 26, 1994 memorandum from John Seitz, EPA’s Director of Office of 

Air Quality Planning and Standards, to David Howekamp of EPA Region IX 

provides two ways for inclusion of these ERCs as growth by stating that “A state 

may choose to show that the magnitude of the pre-1990 ERCs (in absolute 

tonnage) was included in the growth factor, or the state may choose to show that 

it was not included in the growth factor, but in addition to anticipated general 

growth.” 

By including the pre-baseline ERCs in the growth factor, the District has selected 

the first methodology provided in Seitz’s memorandum. However, in either case, 

the purpose is to show that 

baseline inventory + growth + ERCs (pre-baseline) - offsets - reductions 

will result in a projected inventory adequate to attain the federal 1-hour ozone 

standard and any applicable rate of progress, where 

growth = non-permitted growth + permitted growth 

offsets = ERCs (post-baseline) + ERCs (pre-baseline) 

reductions = reductions required by the measures in the Plan 
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3.4.3.2 Growth Estimate 

The District used reports from the California Emission Forecasting System 

(CEFS) to generate emissions trends and growth estimates in this Extreme 

OADP. The California Air Pollution Control and Air Quality Management Districts 

and the California Air Resources Board (ARB) jointly developed the SIP/CCOS 

emissions inventory and associated emissions projections. Staff used the 

CEFS’s computer tools to develop projections and the emission estimates based 

on the most currently available growth and control data available at the time of 

the forecast runs. The CEFS was developed in the 1990s to assist in the 

development of air quality plans, determining how and where air pollution can be 

reduced, tracking progress towards meeting plans goals and mandates, and in 

constructing emission trends. 

A key component of CEFS is the growth data. In preparation for CCOS, the 

growth factors were enhanced in 2001. The February 26, 2001 report titled

“Development of Emissions Growth Surrogates and Activity Projections Used in 

Forecasting Point and Area Source Emissions” describes efforts undertaken to 

identify the most appropriate growth surrogates for stationary and area sources. 

The growth estimates generated by CEFS include growth in emissions requiring 

offsets under New Source Review Rule as well those that can be accommodated 

without triggering offsets. Tables 3-2 and 3-3 show total growth rates of 15 

tons/day of NOx, and 9.8 tons/day of VOCs. These tables also show the 

expected reductions for each pollutant from the measures contained or relied on 

in this Plan. As shown in Tables 3-2 and 3-3, the projected inventory for 2010 

incorporates the projected growth as well as the expected controls from the 

measures contained in the Plan. Notwithstanding slight rounding errors, the 

projected 2010 inventory equals the baseline inventory plus the projected growth 

minus the expected reductions from the controls contained in the Plan. 

3.4.3.3 Pre-Baseline Offset Use 

Under District’s New Source Review Rule 2201, new sources with emissions 

exceeding the following level must offset their emissions: 

 NOx ................................... 20,000 lbs/year 

 VOC.................................... 20,000 lbs/year 

 PM10.................................. 29,200 lbs/year 

 SOx.................................... 54,750 lbs/year 

 CO (attainment area) ............. 200,000 lbs/year 

 CO (non-attainment area) ....... 30,000 lbs/year 

Additionally, for existing facilities with emissions meeting or exceeding the above 

levels, any increase in emissions must be offset. The amount of offsets required 

was estimated by establishing the percentage of permitting actions for each 

source category that would be subject to offset requirements under Rule 2201. 
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Table 3-2 

Estimated NOx Growth, Control, and Estimated Offset Use for Stationary Sourc

SUMMARY 

CATEGORY NAME 

2000 

Emissions 

Tons/day 

Growth Factor (%) Estimated 

Growth 

(tons/day) 

Control 

Factor (%) 

Required 

Reductions 

(tons/day) 

2010 

Emissions 

Tons/day 

R

STATIONARY SOURCES 

FUEL COMBUSTION 

ELECTRIC UTILITIES 3.1 15.3% 0.5 11.2% 0.4 3.1 

COGENERATION 9.0 38.5% 3.5 46.8% 5.8 6.3 

OIL AND GAS 

PRODUCTION 

(COMBUSTION) 

39.6 2.3% 0.9 39.4% 16.0 25.4 

PETROLEUM 

REFINING 

(COMBUSTION) 

1.5 0.1% 0.0 2.8% 0.04 1.5 

MANUFACTURING 

AND INDUSTRIAL 36.5 19.0% 7.0 9.5% 4.1 39.7 

FOOD AND 

AGRICULTURAL 

PROCESSING 

26.9 -2.5% -0.7 10.1% 2.6 23.6 

SERVICE AND COMMERCIAL 13.7 11.7% 1.6 5.9% 0.9 14.4 

OTHER (FUEL 

COMBUSTION) 0.0 0.0% 0.0 0.0% 0.0 0.0 

TOTAL FUEL COMBUSTION 130.2 114.0 
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Table 3-2 

Estimated NOx Growth, Control, and Estimated Offset Use for Stationary Sources1 

SUMMARY 

CATEGORY NAME 

2000 

Emissions 

Tons/day 

Growth Factor (%) Estimated 

Growth 

(tons/day) 

Control 

Factor (%) 

Required 

Reductions 

(tons/day) 

2010 

Emissions 

Tons/day 

R

WASTE DISPOSAL 

SEWAGE TRTMNT 0.0 0.0 0.0 0.0 0.0 

LANDFILLS 0.0 0.0 0.0 0.0 0.0 

INCINERATORS 0.1 13.9% 0.0 0.2% 0.0 0.1 

SOIL REMEDTN 0.0 0.0 0.0 0.0 0.0 

OTHER 0.0 0.0 0.0 0.0 0.0 

* TOTAL WASTE DISP 0.1 0.2% 0.0 0.1 

CLEANING AND SURFACE COATINGS 

LAUNDERING 0.0 0.0 0.0 0.0 0 

DEGREASING 0.0 0.0 0.0 0.0 0 

COATINGS & REL. 

PROCESS SOLV 0.0 0.0 0.0 0.0 0 

PRINTING 0.0 0.0 0.0 0.0 0 

ADHESIVES & 

SEALANTS 0.0 0.0 0.0 0.0 0 

OTHER (CLEANING & 

SFC COATINGS) 0.0 109.1% 0.0 0.0% 0.0 0.0 

* TOTAL CLN/SFC 0.0 0.0 

PETROLEUM PRODUCTION AND MARKETING

OIL/GAS PROD. 0.2 40.4% 0.1 0.1% 0.0 0.2 

PET. REFINING 0.1 0.0% 0.0 0.0% 0.0 0.1 

PET. MARKETING 0.0 39.7% 0.0 0.6% 0.0 0.0 

* TOTAL PETROLEUM 

PROD.& MARKETING 0.3 0.4 
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Table 3-2 

Estimated NOx Growth, Control, and Estimated Offset Use for Stationary Sources1 

SUMMARY 

CATEGORY NAME 

2000 

Emissions 

Tons/day Growth Factor (%) 

Estimated 

Growth 

(tons/day) 

Control 

Factor (%) 

Required 

Reductions 

(tons/day) 

2010 

Emissions 

Tons/day 

R

INDUSTRIAL PROCESSES

CHEMICAL 0.1 20.6% 0.0 0.2% 0.0 0.2 

FOOD AND 

AGRICULTURE 9.2 -3.0% -0.3 -0.1% -0.0 9.0 

MINERAL 

PROCESSES 1.5 17.4% 0.3 0.0% 0.0 1.7 

METAL PROCESSES 0.0 6.0% 0.0 0.0% 0.0 0.0 

WOOD AND PAPER 0.0 0.0 0.0 0.0% 0.0 0.0 

GLASS AND RELATED 

PRODUCTS 12.0 18.0% 2.2 28.9% 4.1 10.1 

ELECTRONICS 0.0 107.7% 0.0 0.0% 0.0 0.0 

OTHER (INDUSTRIAL 

PROCESSES) 0.0 36.8% 0.0 0.0% 0.0 0.0 

* TOTAL INDUSTRIAL 

PROCESSES 22.9 21.0 

** TOTAL 

STATIONARY 

SOURCES 

153.4 135.4 

GRAND TOTAL FOR 

SJVUAPCD 153.4 15.0 135.4 

1 This table represents a subset of the emissions inventory data used elsewhere in this Extreme OADP, and is used only fo

estimating emission reduction credit use. It reflects only changes that are projected to occur from 2000 to 2010 in the statiocomponent of the overall inventory. Also, it was derived from an ARB emissions inventory that is different from the Central (CCOS) emissions inventory Version 2.11 used for the remainder of this document, but that was developed with data consinventory. Consequently, emissions data presented in Table 3-2 may show minor differences from those in Table 3-1 for sshould not be directly compared with Table 3-1 or with other emissions data derived from Table 3-1. 
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Table 3-3 

Estimated VOC Growth, Control, and Estimated Offset Use for Stationary Sourc

SUMMARY 

CATEGORY NAME 

2000 

Emissions 

Tons/day 

Growth Factor (%) Estimated 

Growth 

(tons/day) 

Control 

Factor (%) 

Required 

Reductions 

(tons/day) 

2010 

Emissions 

Tons/day 

STATIONARY SOURCES 

FUEL COMBUSTION 

ELECTRIC UTILITIES 0.4 37.7% 0.1 -0.1% 0.0 0.5 

COGENERATION 0.7 27.0% 0.2 -0.0% 0.0 1.0 

OIL AND GAS 

PRODUCTION 

(COMBUSTION) 

2.7 15.6% 0.4 0.0% 0.0 3.2 

PETROLEUM 

REFINING 

(COMBUSTION) 

0.1 0.0% 0.0 0.0% 0.0 0.1 

MANUFACTURING 

AND INDUSTRIAL 0.3 26.3% 0.1 0.1% 0.0 0.4 

FOOD AND 

AGRICULTURAL 

PROCESSING 

2.7 -2.7% -0.1 -0.1% 0.0 2.6 

SERVICE AND COMMERCIAL 1.2 10.5% 0.1 -0.0% 0.0 1.3 

OTHER (FUEL 

COMBUSTION) 0.0 0.0% 0.0 0.0% 0.0 0.0 

* TOTAL FUEL 

COMBUSTION 8.1 9.0 

WASTE DISPOSAL 

SEWAGE 

TREATMENT 0.0 22.0% 0.0 0.6% 0.0 0.0 

LANDFILLS 2.8 21.8% 0.6 0.0% 0.0 3.4 

INCINERATORS 0.0 0.0 0.0 0.0 
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Table 3-3 

Estimated VOC Growth, Control, and Estimated Offset Use for Stationary Sources1 

SUMMARY 

CATEGORY NAME 

2000 

Emissions 

Tons/day 

Growth Factor (%) Estimated 

Growth 

(tons/day) 

Control 

Factor (%) 

Required 

Reductions 

(tons/day) 

2010 

Emissions 

Tons/day 

WASTE DISPOSAL (cont.) 

SOIL REMEDIATION 0.0 13.6% 0.0 0.0% 0.0 0.0 

OTHER (WASTE 

DISPOSAL) 0.5 26.3% 0.1 0.0% 0.0 0.6 

* TOTAL WASTE 

DISPOSAL 3.3 -0.0% 4.0 

CLEANING AND SURFACE COATINGS 

LAUNDERING 0.1 23.6% 0.0 0.4% 0.0 0.1 

DEGREASING 11.1 -7.7% -0.9 86.4% 8.8 1.5 

COATINGS & 

RELATED PROCESS 

SOLVENTS 

13.8 29.0% 4.0 2.1% 0.4 17.5 

PRINTING 1.5 16.9% 0.2 -0.0% 0.0 1.7 

ADHESIVES AND 

SEALANTS 0.7 -16.8% -0.1 -0.0% 0.0 0.6 

OTHER (CLEANING & 

SURFACE COATINGS) 2.8 43.3% 1.2 -0.0% -0.0 4.0 

*TOTAL CLEANING & 

SURFACE COATINGS 29.9 25.4 

PETROLEUM PRODUCTION AND MARKETING 

OIL/GAS PROD. 31.6 0.4% 0.1 0.9% 0.3 31.4 

PET. REFINING 1.4 0.3% 0.0 2.1% 0.0 1.4 

PET. MARKETING 6.6 21.9% 1.5 9.6% 0.8 7.3 

* TOTAL PETROLEUM 

PROD. & MARKETING 39.6 40.1 
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Table 3-3 

Estimated VOC Growth, Control, and Estimated Offset Use for Stationary Sources1 

SUMMARY 

CATEGORY NAME 

2000 

Emissions 

Tons/day 

Growth Factor (%) Estimated 

Growth 

(tons/day) 

Control 

Factor (%) 

Required 

Reductions 

(tons/day) 

2010 

Emissions 

Tons/day 

INDUSTRIAL PROCESSES 

CHEMICAL 1.9 31.7% 0.6 0.0% 0.0 2.5 

FOOD & 

AGRICULTURE 10.7 13.0% 1.4 2.7% 0.3 11.8 

MINERAL 

PROCESSES 0.3 22.8% 0.1 0.0% 0.0 0.4 

METAL PROCESSES 0.2 0.4% 0.0 0.0% 0.0 0.2 

WOOD & PAPER 0.0 0.0 0.0 0.0 

GLASS & RELATED 

PRODUCTS 0.1 15.0% 0.0 0.0% 0.0 0.1 

ELECTRONICS 0.0 105.9% 0.0 0.0% 0.0 0.0 

OTHER (INDUSTRIAL 

PROCESSES) 0.1 10.0% 0.0 -0.1% 0.0 0.1 

* TOTAL INDUSTRIAL 

PROCESSES 13.3 15.1 

** TOTAL 

STATIONARY 

SOURCES 94.2 93.5 

GRAND TOTAL FOR 

SJVUAPCD 94.2 9.8 93.5 

1 This table represents a subset of the emissions inventory data used elsewhere in this Extreme OADP, and is used only fo

estimating emission reduction credit use. It reflects only changes that are projected to occur from 2000 to 2010 in the statiocomponent of the overall inventory. Also, it was derived from an ARB emissions inventory that is different from the Central (CCOS) emissions inventory Version 2.11 used for the remainder of this document, but that was developed with data consinventory. Consequently, emissions data presented in Table 3-2 may show minor differences from those in Table 3-1 for sshould not be directly compared with Table 3-1 or with other emissions data derived from Table 3-1. 
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For each source category, this percentage was established based on past 

permitting history, the fraction of sources in the category with emissions at or 

above the offset trigger levels, and the historical permitting activity for the source 

category. The District used the following factors in estimating the potential need 

for offsets: 

• All increases from modifications to existing sources with potential 

emissions at or above the above offset thresholds would require offsets 

(District Rule 2201). 

• New sources with emissions exceeding the above offset thresholds would 

require offsets (District Rule 2201). 

• The percentage of sources that meet any of the above criteria was 

estimated by examining past permitting history and by projecting future 

permitting based on the estimated growth. For instance, the majority of 

permitting actions with increases in emissions from oil production facilities 

come from sources with potential emissions in excess of the above offset 

thresholds. Therefore, for that source category, it was assumed that 

100% of increase in overall emissions would require offsets. 

The quantity of required offsets was then established by multiplying the expected 

growth in emissions for each source category by this percentage and the 

expected offset ratio. District rule 2201 establishes offset ratios ranging from 

1.3:1 to 1.5:1 based on the distance from the source of ERCs to the source with 

the increase in emissions. An offset ratio of 1.5:1 applies to all transactions 

where the distance is greater than 15 miles. Historically, most transactions in the 

District involve a distance of greater than 15 miles. For calendar years 2000—

2003, the average offset ratio for all permitting actions was slightly higher than 

1.4:1. Therefore, the District used an average offset ratio of 1.4:1 for these 

calculations. 

Tables 3-2 and 3-3 contain the expected growth, percentage of activities subject 

to offset requirements, and the expected quantity of offsets for each pollutant. 

Although some offsets are expected to come from post-baseline reduction, this 

Plan conservatively assumes that all offsets will be pre-baseline. The expected 

pre-baseline offset usage after 2000 through 2010, as shown in Tables 3-2 and 

3-3, is estimated as follows: 

 NOx .......................................12.1 tons/day 

 VOC ....................................... 8.1 tons/day 

 

As shown above, the quantities of pre-baseline offsets that are expected to be 

used between 2000 and 2010 are less than the estimated growth in emissions for 

each pollutant. As currently adopted, if growth in new and modified sources 

occurs at the rate estimated in this Plan, the use of offsets as provided in Rule 

2201 will ensure that permitted increases in major source emissions will not 

interfere with progress towards attainment of federal 1 hour ozone standards or 
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3-22 

the achievement of the 3 percent per year reduction in ozone precursor 

emissions. As discussed in Chapter 7, the District satisfies the requirement for 

rate of progress with above-mentioned projected inventories and without taking 

credit for the ERCs required of and provided by new and modified stationary 

sources. 

3.4.3.4 Safeguards

In order to assure the use of pre-baseline ERCs do not interfere with attainment 

effort and the applicable rate of progress, this Extreme OADP incorporates the 

following safeguards: 

• The District will place a cap on the amount of pre-baseline credits that can 

be used. Although the District has relied on a number of conservative 

assumptions in estimating the usage quantity of pre-baseline credits, 

some degree of uncertainty exists. For instance, unexpected growth or 

irregular permitting activity may occur for one or more source categories. 

The cap on the use of pre-baseline ERCs will be enforced by tracking the 

use of such credits and disallowing such credits, through permitting 

actions when the above-specified levels are reached. The District Rules 

and Regulations will be amended to require tracking and enforcement of 

the above referenced cap within 12 months after EPA approval of this 

Extreme OADP. Appendix E lists the cap on stationary source growth by 

pollutant. 

• Although some ERCs will come from post-baseline reductions, this 

Extreme OADP conservatively assumes that all offsets will come from prebaseline reductions. As discussed earlier, federal law only requires the 

pre-baseline ERCs to be included in the growth and the attainment 

demonstration. This Extreme OADP assumes that all ERCs will be prebaseline ERCs and, therefore, includes them all in the projected inventory 

as growth. Using a larger than permissible projected inventory leads to 

conservative conclusions relating to the attainment and rate of progress 

demonstrations. 

• Although permissible, this plan does not take credit for reductions and 

mitigations required under the District’s New Source Review Rule. In 

particular, this Plan does not reduce the future years emissions by taking 

credit for the amount of ERCs provided through permitting actions. This 

conservative approach assures that the attainment demonstration is not 

affected by the use of pre-baseline ERCs. 
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3.5 CONFORMITY BUDGETS 

Section 176(c) of the FCAA outlines the conformity provision of the Clean Air Act. 

Federal actions are required to conform to the SIP’s purpose of eliminating or 

reducing the severity and number of exceedances of the NAAQS and achieving 

expeditious attainment of these standards. The FCAA distinguishes 

transportation actions [those undertaken by the Federal Highway Administration 

(FHWA) or the Federal Transit Administration (FTA)] from all other federal 

actions. 

Metropolitan Planning Organizations (MPOs) must make findings that the 

regional transportation plans (RTPs) and transportation improvement programs 

(TIPs) conform to the SIP. They submit this conformity finding along with the 

RTP and TIP, to FHWA and FTA for approval. The conformity finding must 

demonstrate that the emissions associated with the RTP and TIP do not exceed 

“emission budgets” that are contained in the SIP. 

The District’s Amended 2002 and 2005 Rate of Progress Plan for San Joaquin 

Valley Ozone established subarea emissions budgets for each county for ROG 

and NOx for 2005; in addition, the 2003 PM10 Plan established subarea 

emissions budgets for each county for NOx and PM for 2005, 2008 and 2010. 

This Extreme OADP establishes new subarea county emissions budgets for 

ROG and NOx for 2008 and 2010, as provided in Table 3-4 for the purposes of 

conformity. After an adequacy finding by EPA, these new budgets will apply for 

subsequent years, unless these budgets are superseded by new budgets or by 

budgets set for later years. 

Efforts have been made to incorporate the SJVAB MPO’s updated vehicle miles 

traveled (VMT) [submitted as comments in response to the release of EMFAC 

2002 and used in the Amended 2003 PM-10 Plan] into the emissions budgets. 

ARB staff conducted model runs to match the VMT data through adjustments to 

vehicle population. With this approach, emissions budgets reflect not only the 

latest VMT data, but also reflect the additional impact of those data on emissions 

from vehicle starting and from vehicle fuel evaporation. After reviewing the 

EMFAC results, District, ARB and TPA staff reduce the emissions estimates to 

account for any emissions controls that were not included in the model runs, and 

to make other adjustments as warranted to project emissions for future years. 

Table 3-4 reflects emissions reductions benefits of the California Inspection and 

Maintenance (I/M) program, statewide measures affecting mobile sources 

(Chapter 4), and reductions from the District’s Indirect Source Rules (ISR) and 

incentive programs (Chapter 4). 
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Table 3-4 

Transportation Conformity Budgets1

VOC Emissions (tons/day) NOx Emissions (tons/day) 

County 2008 2010 2008 2010 

Fresno 15.8 13.0 33.7 27.7 

Kern (SJVAB) 11.5 9.6 32.7 27.2 

Kings 2.5 2.1 6.2 5.4 

Madera 3.9 3.3 8.4 7.2 

Merced 5.0 4.0 11.4 9.1 

San Joaquin 9.3 7.7 22.4 17.9 

Stanislaus 8.5 7.0 17.4 14.0 

Tulare 8.5 6.9 18.8 15.3 

Total 65.0 53.6 151.0 123.8 

1 All emissions are expressed as summer tons/day, and were derived using EMFAC2002, Version 2.2 (April 2003) with 

updated vehicle population and vehicle miles traveled data. Emissions totals reflect the emissions reductions benefits 

from motor vehicle inspection and maintenance (I/M), state measure reductions, and reductions from the District’s Indirect 

Source Rules (ISR) and mobile source incentive programs; consequently, totals will not match those in Table 3-1 which 

do not reflect these additional control measures. The budget was established by taking the EMFAC results, subtracting 

the emissions reductions benefits, rounding up to the nearest tenth if the hundredths place was “1” or higher. See 

Appendix A for county-specific breakdown of on-road motor vehicle emissions and emissions reductions benefits. 

3.6 EMISSIONS INVENTORY UNCERTAINTIES 

A substantial amount of staff work goes into developing emissions inventories for 

SIPs. In order to prepare a plan in time to meet deadlines, many times the 

inventory used as a basis for modeling must be “frozen” in time at some point3 so 

that modeling can proceed and so that control measures can be evaluated. As 

staff works with the inventory, they often identify issues that need to be 

addressed to make the inventory more accurate, such as possible overestimates 

of source categories, underestimates of source categories, seasonal or other 

temporal changes in emissions that may not be reflected, or spatial distribution 

issues addressing how the emissions are distributed over the modeled area. 

For this Extreme OADP, the following uncertainties were identified after the 

inventory was frozen for use in plan development: inclusion of emissions from 

heavy duty trucks used to haul produce from fields to processing locations; 

inclusion of emissions from heavy duty trucks, entering California from Mexico 

due to the June 2004 Supreme Court decision regarding the North American 

Free Trade Agreement (NAFTA); spatial distribution of on-road motor vehicle 

emissions in the northern four counties vs. the southern four counties; 

discrepancies between two different methods of estimating heavy duty truck 

emissions in the SJVAB; the effects of temperature discrepancies on biogenic 

emissions and resultant predicted ozone levels; and the effects of fires on base 

case ozone levels and whether or not fires should be included in future scenarios 

for control measure evaluation (See Chapter 5). Work continues under CCOS to 

evaluate these and other uncertainties so that their magnitude can be evaluated 

 

3

 For this Extreme OADP, the inventory was frozen in November 2003. 
EXTREME OZONE ATTAINMENT DEMONSTRATION PLAN 

 

 

SJVUAPCD Chapter 3 - Emission Inventory 

3-25 

and their effect on future ozone trends quantified. ARB conducts periodic multiagency meetings to evaluate and discuss SIP emissions inventory issues (see 

Appendix D). 

3.7 CONCLUSION 

Emissions inventory data reflect the best estimates that can be made of the rates 

and chemical composition of air pollutants entering the atmosphere. Although 

some emissions are directly measured (usually those from large stationary 

sources equipped with continuous emissions monitors), most of the inventory is 

estimated using standardized techniques and methodologies. Inventories can 

change over time due to a number of factors including changes in source activity 

level, changes in emissions factors, or changes in the spatial distribution, 

chemical composition, or rate of the emissions. 

This Extreme OADP is based on two types of inventories: a planning inventory 

and a modeling inventory. Air quality planners use the planning inventory to 

study and propose control measures, to track trends in emissions for meeting 

federal Rate of Progress requirements (Chapter 7) and to track the use of ERCs, 

and to assist in demonstrating attainment (Chapter 5). In addition, the on-road 

motor vehicle emissions component of the planning inventory has special 

importance for establishing conformity budgets for transportation planning 

purposes. The modeling inventory provides day-specific information used as 

input for the photochemical model that predicts future ozone levels in the SJVAB. 

The planning and modeling inventories each have cutoff dates for the inclusion of 

control measures (i.e., control measures adopted past the cutoff date are not 

reflected in the inventories and must be subtracted from the results of inventory 

runs and model runs). 

This Extreme OADP uses the most accurate and up to date emission inventories 

possible within the time allowed to meet Federal Clean Air Act requirements. 

Many emission categories within the inventories were updated to reflect current 

data and emission factors. While changes and improvements to the SJVAB’s 

inventories are ongoing, at some point in time the planning and modeling 

inventories must be “frozen” to allow plan development to proceed (i.e., the 

inventory must be frozen so that potential future emission control measures can 

be evaluated for their effectiveness in attaining the federal 1-hour ozone 

standard). Many emission inventory improvement projects are in process or are 

planned, and the results of these and other studies will be reflected in the 

inventories used in future SIP submittals. 
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