AVAQMD 

Federal 8-Hour Ozone Attainment Plan 

(Western Mojave Desert 

Non-attainment Area) 

Adopted on: 

May 20, 2008 

Antelope Valley Air Quality Management District 

43301 Division Street, Suite 206 

Lancaster, California 93535-4649 
 2

This document was prepared by the AVAQMD Planning, Rule-making and Grants section, with 

input from the entire AVAQMD staff. Significant portions of this document were prepared by, 

or are based on work done by, the California Air Resources Board and the South Coast Air 

Quality Management District staffs. The AVAQMD staff greatly appreciates the assistance of 

those agencies in the preparation of this document. 
AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

i

Table of Contents

List of Tables...........................................................................................................................ii

List of Figures.........................................................................................................................ii

Abbreviations and Acronyms .................................................................................................iii

Executive Summary ...................................................................................................................... 1

CHAPTER 1 – Introduction and Background........................................................................... 3

Introduction ................................................................................................................................. 5 

Purpose.................................................................................................................................... 5

Background ................................................................................................................................. 5 

Regulatory History .................................................................................................................. 5

Regional Ozone Planning Chronology ................................................................................... 6

Statement of Issues.................................................................................................................. 6

Federal Legal Requirements................................................................................................... 6

Pollutant Description and Health Effects ............................................................................... 8

Setting...................................................................................................................................... 8

Ozone Trend ............................................................................................................................ 8

CHAPTER 2 – Emission Inventories ........................................................................................ 11

General.................................................................................................................................. 13

Modeled Emission Inventory................................................................................................. 13

Federal Ozone Non-Attainment Area Base Year Emission Inventory .................................. 13

Future Year Emission Inventories......................................................................................... 14

CHAPTER 3 – Control and Contingency Measures................................................................ 17

Existing Control Measures.................................................................................................... 19

Proposed Control Measures.................................................................................................. 19

State Control Measures......................................................................................................... 19

Local Rule Adoption Schedule .............................................................................................. 23

Contingency Measures.......................................................................................................... 24

Required Progress................................................................................................................. 24

Controlled Emission Inventories........................................................................................... 25

Conformity Budgets............................................................................................................... 25

CHAPTER 4 – Attainment Demonstration .............................................................................. 27

Attainment Demonstration ........................................................................................................ 29 

Modeling Approach Overview .............................................................................................. 29

Modeling Domain.................................................................................................................. 30

Model Inputs.......................................................................................................................... 30

Modeling Results................................................................................................................... 30

ARB Weight of Evidence Assessment .................................................................................... 31

Appendices................................................................................................................................... 33

Appendix A - Base Year Emission Inventory.........................................................................A-1 

Appendix B - Future Year Emission Inventories....................................................................B-1 

Appendix C - Transportation Conformity Budgets.................................................................C-1 

Appendix D - Annual Ambient Monitoring Data Summary...................................................D-1 
ii AVAQMD Federal 8-hour Ozone Attainment Plan 

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Appendix E - ARB Weight of Evidence Assessment ............................................................. E-1 

List of Tables 

Table 1 - 2002 Base Year Summary ............................................................................................. 13 

Table 2 - Expected Emission Reductions from Proposed New SIP Measures............................. 23 

Table 3 - AVAQMD Rule Adoption Schedule ............................................................................. 23 

Table 4 - Reasonable Further Progress for the WMDONA.......................................................... 25 

Table 5 - Transportation Conformity Budget (AV portion of WMDONA) ................................. 26 

Table 6 - 2020 Federal Ozone Attainment Demonstration ........................................................... 31 

List of Figures 

Figure 1 - Federal 8-Hour Ozone Design Value Trend................................................................... 9 

Figure 2 - 2002 Base Year Pie Charts (FONA) ............................................................................ 14 

Figure 3 - Forecasted VOC Emission Inventories (FONA).......................................................... 15 

Figure 4 - Forecasted NOx Emission Inventories (FONA) ........................................................... 16 
AVAQMD Federal 8-hour Ozone Attainment Plan 

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Abbreviations and Acronyms 

AQAP.................Air Quality Attainment Plan 

AQMA................Air Quality Management Area 

AQMP ................Air Quality Management Plan 

AVAPCD ...........Antelope Valley Air Pollution Control District 

AVAQMD..........Antelope Valley Air Quality Management District 

CAAQS ..............California Ambient Air Quality Standard 

CALGRID ..........California Photochemical Grid Model 

CARB.................California Air Resources Board 

CCAA.................California Clean Air Act 

CO ......................Carbon Monoxide 

ERC....................Emission Reduction Credit 

FCAA .................Federal Clean Air Act 

FMVCP ..............Federal Motor Vehicle Control Program 

FONA.................Federal Ozone Non-attainment Area 

MDAQMD .........Mojave Desert Air Quality Management District 

MPR ...................Model Performance Ratio 

NAAQS ..............National Ambient Air Quality Standard 

NOX ....................Oxides of Nitrogen 

NSR....................New Source Review 

O3........................Ozone 

RACT .................Reasonably Available Control Technology 

ROG ...................Reactive Organic Gases 

ROP....................Rate of Progress 

RRF ....................Relative Reduction Factor 

SBCAPCD..........San Bernardino County Air Pollution Control District 

SCAB .................South Coast Air Basin 

SCAG .................Southern California Association of Governments 

SCAQMD...........South Coast Air Quality Management District 

SCAQS87...........1987 Southern California Air Quality Study 

SCOS97..............1997 Southern California Ozone Study 

SDMAQMA.......Southeast Desert Modified Air Quality Management Area 

SSAB..................Salton Sea Air Basin 

tpaad ...................Tons per Annual Average Day 

tposd ...................Tons per Ozone Seasonal Day 

UAM...................Urban Airshed Model 

USEPA ...............United States Environmental Protection Agency 

VMT...................Vehicle Miles Traveled 

VOC ...................Volatile Organic Compounds 

WMDONA.........Western Mojave Desert Ozone Non-attainment Area 
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Executive Summary 

The United States Environmental Protection Agency (USEPA) designated the Western Mojave 

Desert non-attainment area as non-attainment for the 8-hour ozone National Ambient Air Quality 

Standard (NAAQS) pursuant to the provisions of the Federal Clean Air Act (FCAA). The 

Antelope Valley Air Quality Management District (AVAQMD) is included in the Western 

Mojave Desert non-attainment area. The AVAQMD has adopted State and Federal attainment 

plans for the region within its jurisdiction. The most recent such plan that was approved by 

USEPA is the AVAQMD 2004 Ozone Attainment Plan adopted in 2004. 

The AVAQMD has reviewed and updated all elements of the ozone plan. The AVAQMD will 

be in attainment of the 8-hour NAAQS for ozone by 2021. 

This document includes the latest planning assumptions regarding population, vehicle activity 

and industrial activity. This document addresses all existing and forecast ozone precursorproducing activities within the Antelope Valley through the year 2020. This document includes 

all necessary information to allow general and transportation conformity findings to be made 

within the Antelope Valley. 
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CHAPTER 1 – Introduction and Background 

Purpose 

Regulatory History 

Statement of Issues 

Federal Legal Requirements 

State Legal Requirements 

Pollutant Descriptions 

Health Effects 

Setting 

Ozone Trend 
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INTRODUCTION 

Purpose 

The Western Mojave Desert non-attainment area (as defined in 40 CFR 81.305) was designated 

non-attainment for the NAAQS for ozone by USEPA on April 15, 2004. The Western Mojave 

Desert Ozone Non-attainment Area (WMDONA) includes part of the San Bernardino County 

portion of the MDAQMD, as well as the Antelope Valley portion of Los Angeles County. The 

AVAQMD has experienced ambient ozone concentrations in excess of the 8-hour ozone 

NAAQS. This document: (1) demonstrates that the AVAQMD will meet the primary required 

federal ozone planning milestones, attainment of the 8-hour ozone NAAQS by June 2021; (2) 

presents the progress the AVAQMD will make towards meeting all required ozone planning 

milestones; and (3) discusses the newest 0.075 part per million 8-hour ozone NAAQS, 

preparatory to an expected non-attainment designation for the new NAAQS. This document 

satisfies 42 U.S.C. §§7410, 7502, 7504 and 7511a (FCAA §§110, 172, 174, and 182) regarding 

implementation plans, non-attainment plan provisions, planning procedures, and ozone plan 

submissions and requirements for the 8-hour NAAQS. 

BACKGROUND 

Regulatory History 

The USEPA designated the desert part of Los Angeles County as non-attainment and classified it 

as Moderate for the 8-hour standard. This area was classified based on an ozone design value 

calculated from 2001 through 2003 concentrations in the region. The Moderate classification 

requires attainment of the 8-hour ozone NAAQS by June 2010, six years after the date of 

designation. 

The desert portion of Los Angeles County was established as it’s own air district as of July 1, 

1997, the Antelope Valley Air Pollution Control District (AVAPCD), pursuant to former Health 

& Safety Code (H&SC) §40106 (Statutes 1996 ch 542, Repealed Statutes 2001 ch. 163). This air 

district was replaced by the AVAQMD on January 1, 2002, pursuant to H&SC §41300 et seq 

(Statutes 2001 ch. 163). As a successor district to the SCAQMD, the AVAQMD assumes the 

authorities and duties of the SCAQMD for the Antelope Valley (H&SC §41302). 

The SCAQMD addressed the desert portion of Los Angeles County in the 1991 AQMP, the 1994 

AQMP, and the 1997 AQMP. The 1994 AQMP is the most recent ozone attainment plan for the 

desert portion of Los Angeles County that has been approved by USEPA. The USEPA has 

approved a revision to the 1997 AQMP that was adopted after the formation of the AVAPCD. 

The AVAQMD adopted the AVAQMD 2004 Ozone Attainment Plan on April 20, 2004. This 

document replaces or updates all previously submitted federal ozone plans. 
6 AVAQMD Federal 8-hour Ozone Attainment Plan 

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Regional Ozone Planning Chronology 

1989 - CARB designates SEDAB as non-attainment for ozone CAAQS 

1990 - CARB classifies the SEDAB as moderate ozone non-attainment 

November, 1990 - Adoption of Federal Clean Air Act Amendments 

September 9, 1994 – SCAQMD adopts 1994 AQMP 

November 15, 1994 – SCAQMD submits 1994 AQMP to CARB 

July 10, 1996 – CARB submits 1994 AQMP to USEPA 

1996 - SEDAB is subdivided into the Mojave Desert Air Basin (MDAB) and the Salton Sea Air 

Basin (SSAB) 

November 15, 1996 – SCAQMD adopts 1997 AQMP 

January 8, 1997 – USEPA approves 1994 AQMP into State Implementation Plan (63 FR 1150) 

February 5, 1997 – CARB submits 1997 AQMP to USEPA 

July 1, 1997 – AVAPCD is formed 

April 21, 1998 – USEPA approves CO portion of 1997 AQMP for SCAB (63 FR 19661) 

July 24, 1998 – USEPA approves NO2 portion of 1997 AQMP for SCAB (63 FR 39747) 

January 12, 1999 – USEPA proposed limited approval/disapproval for remainder of 1997 

AQMP, approving emission inventories but disapproving attainment demonstration, 

reasonable further progress, milestones and proposed control measures (64 FR 1770) 

December 10, 1999 – SCAQMD adopts update to 1997 AQMP that fixes problems identified in 

January 12, 1999 USEPA action 

February 4, 2000 – CARB submits revised 1997 AQMP to USEPA 

April 10, 2000 – USEPA approves 1997 AQMP 

January 1, 2002 – AVAPCD changed to AVAQMD 

April 20, 2004 - Adoption of AVAQMD 2004 Ozone Attainment Plan 

Statement of Issues 

The Antelope Valley is downwind of the Los Angeles basin, and to a lesser extent, is downwind 

of the San Joaquin Valley. Prevailing winds transport ozone and ozone precursors from both 

regions into and through the Antelope Valley during the summer ozone season. These transport 

couplings have been officially recognized by CARB.1Local Antelope Valley emissions 

contribute to exceedances of both the NAAQS and CAAQS for ozone, but the Antelope Valley 

would be in attainment of both standards without the influence of this transported air pollution 

from upwind regions. 

Federal Legal Requirements 

The AVAQMD must adopt a plan that provides for the implementation, maintenance and 

enforcement of the NAAQS within three years after promulgation of the NAAQS. The plan is to 

include enforceable emission limitations, provide for a monitoring program, provide for a permit 

program (including a new source review program), contingency measures, and air quality 

 

1

“Ozone Transport: 2001 Review,” April 2001, CARB identifies the South Coast Air Basin as having an 

overwhelming and significant impact on the Mojave Desert Air Basin (which includes the Antelope Valley) and the 

San Joaquin Valley as having an overwhelming impact on the MDAB. 
AVAQMD Federal 8-hour Ozone Attainment Plan 

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7

modeling (42 U.S.C. §7410(a); FCAA §110(a)). The SCAQMD met this requirement with their 

1991 Air Quality Management Plan and its 1994 update. This document represents an update to 

the Antelope Valley portion of that plan. The AVAQMD has adopted enforceable emission 

limitations, has a monitoring program in place (at Lancaster), maintains a permit program 

(including a New Source Review program with an ambient air quality modeling requirement), 

and has performed an attainment demonstration using air quality modeling. This document does 

not include any contingency measures, as any such contingent reductions must occur in the 

upwind areas that are responsible for the Antelope Valley’s ozone NAAQS exceedances. 

This document incorporates all reasonably available control measures (all such measures have 

already been adopted for the Antelope Valley). This document includes a comprehensive, 

accurate and current inventory of actual emissions (42 U.S.C. §7502(c)(3), 7511a(a)(1); FCAA 

§§172(c)(3), 182(a)(1)). 

This document discusses reasonable further progress (42 U.S.C. §§7502(c)(2), 7511a(b)(1); 

FCAA §§172(c)(2), 182(b)(1)) for the applicable periodic milestone dates (2002, 2005 and 2007) 

(42 U.S.C. §7511a(g); FCAA §182(g)). The Antelope Valley is not capable of meeting the 

reasonable further progress milestones on its own; the target levels would require reductions in 

source categories that are not under the jurisdiction of the AVAQMD (specifically mobile 

sources). 

This document has been coordinated with the transportation planning process (42 U.S.C. §7504; 

FCAA §174). The document includes an on-road mobile source emission budget for the 

Antelope Valley, and also includes the on-road mobile source emission budget for the entire 

Southeast Desert Modified AQMA as an appendix. 

This document updates the Antelope Valley emissions inventory (42 U.S.C. 7511a(a)(1); FCAA 

§182(a)(1)). The SCAQMD met the original inventory requirement with their 1991 Air Quality 

Management Plan and subsequent updates. 

The AVAQMD has an enhanced non-attainment pollutant monitoring program, requires 

reasonably available control technology, has an enhanced vehicle inspection and maintenance 

program, a De Minimis rule, and a gasoline vapor recovery rule. The District participates in the 

state’s Clean-Fuel Vehicle Program, and performs periodic transportation activity consistency 

demonstrations in conjunction with the Southern California Association of Governments 

(including a review of vehicle miles traveled growth). The AVAQMD controls oxides of 

nitrogen (NOx) in addition to Volatile Organic Compounds (VOC), and is addressing both 

pollutants in this document. The AVAQMD new source review program defines sources 

emitting 25 tons per year or more as major and requires offsets at a 1.3 to 1 ratio (42 U.S.C. 

§§7511a(d), 7511a(d)(2); FCAA §§182(d) 182(d)(2)). Employer trip rules (42 U.S.C. 

§7511a(d)(1); FCAA §182(d)(1)) have been shown to be not cost-effective for the AVAQMD 

due to low population density. 
8 AVAQMD Federal 8-hour Ozone Attainment Plan 

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Pollutant Description and Health Effects 

Ozone (or O3) is a colorless gas that is a highly reactive form of oxygen. It has a strong odor 

when highly concentrated. Ozone can occur naturally but can also be formed from other 

compounds through photochemistry, a complex system of reactions with hydrocarbons and 

oxides of nitrogen in the presence of sunlight (ultraviolet). The MDAB experiences ozone 

concentrations in excess of the State and Federal ambient air quality standards.

Ozone can cause respiratory irritation and discomfort, making breathing more difficult during 

exercise. Ozone can reduce the respiratory system’s ability to remove inhaled particles, increase 

pulse rate, decrease blood pressure and reduce the body’s ability to fight infection. After six 

hours of exposure a healthy person can have significant reduction of lung function. It is an 

irritant towards the skin, eyes, upper respiratory system, and mucous membranes, although 

symptoms disappear after exposure. It may also be a carcinogen. 

Setting 

The Antelope Valley is the desert portion of Los Angeles County. The AVAQMD has been 

designated non-attainment for the 8-hour ozone NAAQS by USEPA as a portion of the Western 

Mojave Desert non-attainment area in 40 CFR 81.305. The ozone design value classifies the 

area as a Moderate non-attainment area with 2010 as the required attainment year (42 U.S.C. 

7511(a)(2); FCAA §181(a)(2)). 

The Antelope Valley covers 1300 square miles and included 219,628 persons as of the 1990 

census (approximately 400,000 in 2002), centered within the cities of Lancaster and Palmdale. 

The region is characterized by a wide, arid valley little precipitation. Air Force Plant 42 and a 

portion of Edwards Air Force Base are located in the area. 

The primary roadways in the Antelope Valley are State Route 14 and State Route 18. Both of 

these arterials carry a substantial amount of daily commute traffic from the region into the 

Greater Los Angeles Basin. 

The Antelope Valley is primarily a bedroom community, but does have significant aerospace 

development and manufacturing on Plant 42 (Boeing, Lockheed Martin and Northrop Grumman 

all lease facilities on the base from the Air Force). 

Ozone Trend 

The Antelope Valley has experienced some improvement in 8-hour average ozone, as displayed 

in Figure 1 (the superimposed line is the three-year average trend line). Note the significant 

change from 1998 to 1999 - 1998 was a hot year, and 1999 a cool year. 
AVAQMD Federal 8-hour Ozone Attainment Plan 

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Figure 1 - Federal 8-Hour Ozone Design Value Trend 

0

0.02

0.04

0.06

0.08

0.1

0.12

0.14

0.16

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Eight-Hour Ozone Value (ppm)

Maximum

84 ppb Design Value Trend

(NAAQS

)
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CHAPTER 2 – Emission Inventories 

General 

Modeled Emission Inventory 

Base Year 

Future Years 
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General 

Ozone planning requirements call for the use of seasonal inventories representing emissions 

during a typical summer day (since ozone concentrations are typically highest under summer 

weather conditions). This document includes ozone seasonal day inventories, in units of tons per 

ozone seasonal day (or tons per os day, or tposd), unless otherwise indicated. All emissions 

presented in this document have been adjusted or calculated in terms of ozone seasonal day 

emissions. 

Federal ozone planning requirements call for emissions in terms of Volatile Organic Compounds 

(VOC), while State ozone planning requirements call for emissions in terms of Reactive Organic 

Gases (ROG). Due to changes in each definition, there is no effective difference between the 

two terms (for example, ethane is now excluded from both definitions). For purposes of this 

document and attainment planning, the District considers these terms interchangeable. 

Modeled Emission Inventory 

The emission inventory for the AVAQMD is provided in Appendix A of this document. 

Complete documentation for Los Angeles County emissions, including emission inventory 

calculation methodologies, are available from the following web address: 

http://www.arb.ca.gov/ei/maps/basins/abmdmap.htm

Federal Ozone Non-Attainment Area Base Year Emission Inventory 

The initial Federal base year for emission inventory purposes is 2002. 2002 is used as the base 

year inventory for all growth scenarios in this document. The base year emission inventory is 

presented in Appendix A; a summary is presented in Table 1 below. Figure 2 presents the base 

year source category contributions in basic pie chart format (VOC on the left, NOx on the right). 

Mobile sources were the primary emitters in the Antelope Valley in 2002. 

Table 1 - 2002 Base Year Summary 

2002 VOC 2002 NOx

Point 6.04 2.03

Area 4.38 0.37

Other Mobile 4.09 15.21

On-Road Mobile 10.11 13.99

Totals: 24.62 31.60

(tons per ozone seasonal day)
14 AVAQMD Federal 8-hour Ozone Attainment Plan 

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Figure 2 - 2002 Base Year Pie Charts (FONA) 

Point VOC

25%

Area VOC

18%

Other Mobile VOC

17%

On-Road Mobile VOC

40%

Point NOx

6%

Area NOx

1%

Other Mobile NOx

49%

On-Road Mobile NOx

44%

Future Year Emission Inventories 

Future year or forecasted emission inventories are estimated by multiplying a base year value for 

each category by a ‘growth code’ for a given future year. The ‘growth code’ is indexed to the 

base year (2002 for this document), so that its value for the base year is 1.00. This allows the 

growth code to estimate future activity in terms of emissions; if the growth code for the year 

2007 is 1.50, activity in that category (and resulting emissions) is expected to be 50 percent 

greater than in 2002. The growth codes used to forecast point sources are available from CARB. 

Forecasted VOC and NOx inventory summaries for each year of interest are presented in Figures 

3 and 4 respectively (the base year is included in each figure for reference). Future year 

emission inventories are presented in Appendix B. 
AVAQMD Federal 8-hour Ozone Attainment Plan 

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Figure 3 - Forecasted VOC Emission Inventories 

0.00

5.00

10.00

15.00

20.00

25.00

30.00

2002 2008 2011 2014 2017 2020

tons per ozone seasonal day

Point VOC

Area VOC

Other Mobile VOC

On-Road Mobile VOC

AV VOC
16 AVAQMD Federal 8-hour Ozone Attainment Plan 

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Figure 4 - Forecasted NOx Emission Inventories 

0.00

5.00

10.00

15.00

20.00

25.00

30.00

35.00

2002 2008 2011 2014 2017 2020

Tons per ozone seasonal day

Point NOx

Area NOx

Other Mobile NOx

On-Road NOx

AV NOx
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CHAPTER 3 – Control and Contingency Measures 

Existing Control Measures 

Proposed Control Measures 

Rule Adoption Schedule 

Contingency Measures 

Required Progress 

Controlled Emission Inventories 

Conformity Budgets 
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Existing Control Measures 

The current AVAQMD set of rules and regulations represents a broad set of control measures for 

AVAQMD sources. The AVAQMD has in place Reasonably Available Control Technology 

(RACT) requirements for the majority of sources (including gasoline dispensing vapor control), 

as well as a New Source Review program with a 25 ton per year major source level and a 1.3:1 

offset ratio requirement. In 2006, the AVAQMD committed to taking action on several Federal 

RACT categories.

2

 The AVAQMD has recently adopted a Federal RACT rule for aerospace 

coating.3 The AVAQMD had committed to adopting an additional RACT rule by the end of 

2007 (see below) – the AVAQMD will update the adoption schedule for these actions. 

Proposed Control Measures 

The AVAQMD is not proposing to adopt any additional control measures for direct ozone 

precursor reduction purposes. However, the AVAQMD is committed to having all applicable 

Federal RACT rules, and is currently performing analyses on the feasibility of adopting 

additional rules under the State of California “all feasible measures” mandate. In addition, the 

AVAQMD will experience additional future emission reductions resulting from existing and 

proposed Federal and State control measures affecting mobile and area sources (see below). 

State Control Measures 

The California Air Resources Board (CARB or ARB) is the State agency responsible for 

ensuring clean air in California. Under State law, ARB has the responsibility to develop State 

Implementation Plan strategies for mobile sources and consumer products, to coordinate SIP 

strategies with the Bureau of Automotive Repair (BAR) and Department of Pesticide Regulation 

(DPR), and to review local plans for attaining the State and Federal ambient air quality 

standards. 

ARB adopted a State Strategy for California’s 2007 SIP in September, 2007. The State Strategy 

is comprehensive; it is designed to enable local districts attain federal air quality standards 

through a combination of technologically feasible, cost-effective, and far reaching measures for 

motor vehicles and other statewide sources. The 2007 State Strategy is also the first to address 

the federal 8-hour ozone standard – it represents a transition from the less stringent 1-hour 

standard that was the benchmark for previous SIPs. The State Strategy also includes measures 

that will contribute to attainment of the federal standard for fine particulates (PM2.5) by the 2014 

PM2.5 deadline. The South Coast Air Basin (SCAB) and the San Joaquin Valley are designated 

nonattainment for the federal PM2.5 standard. 

California first enacted passenger car exhaust standards in 1973. Today the State’s mobile 

source control program addresses a wide variety of on- and off-road vehicles and engines, 

gasoline and diesel fuel standards, and engine maintenance requirements. The existing program 

 

2

“8-Hour Reasonably Available Control Technology – State Implementation Plan Analysis (RACT SIP Analysis),” 

August, 2006 

3

“Rule 1124 – Aerospace Assembly and Component Manufacturing Operations,” adopted March 20, 2007 
20 AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

is projected to reduce emissions from passenger vehicles and heavy-duty trucks by 

approximately 1/3 between 2006 and 2014. The State Strategy ARB adopted in 2007 will result 

in a greater than 50 percent reduction in emissions from all mobile sources in the South Coast 

Air Basin by 2014. Most of the controls in the State Strategy will be implemented statewide, and 

directly benefit the entire state. Some will uniquely target the South Coast and San Joaquin 

Valley Air Basins, directly reducing emissions in the State’s most polluted areas, and indirectly 

improving air quality in downwind areas including Ventura, Antelope Valley, the Mojave Desert 

area, and the Coachella Valley. 

The State Strategy addresses three key mobile source issues: the need to clean up the legacy 

diesel fleets, the national and international nature of many diesel fleets, and limitations on SIP 

credit for unsecured funding. 

The total emission reductions and the obligation to propose specific measures for Board 

consideration would become enforceable upon approval by U.S. EPA of the State Strategy and 

each district’s attainment plan. While the State Strategy includes estimates of the emission 

reductions from each of the individual new measures, it is important to note that the State’s 

commitment is to achieve the aggregate emission reductions identified for the adopted State 

Strategy, from the baseline emissions identified in the SIP. Therefore, if a particular measure 

does not achieve its expected emission reductions, the State still commits to achieving the total 

aggregate emission reductions, whether this is realized through additional reductions from the 

new measures, or from alternative control measures or incentive programs. If actual emission 

decreases occur that exceed the projections reflected in the emission inventories and the State 

Strategy, the actual emission decreases may be counted toward meeting ARB’s total emission 

reduction commitments. 

ARB’s emission reduction commitments may be achieved through a combination of actions 

including but not limited to the implementation of control measures; the expenditure of local, 

state or federal incentive funds; or through other enforceable measures. 

Because ARB scientists determined that reducing emissions of one pollutant, oxides of nitrogen 

(NOx), is the most beneficial in reducing levels of both ozone and PM2.5, the state plan focuses 

on curbing pollution from the sources that produce nearly 90 percent of the state's NOx. These 

sources include cars, heavy duty trucks, large off-road equipment, ships and locomotives. The 

baseline emission inventories used to develop the 2007 and 2008 federal plans throughout the 

state incorporate reductions from control measures adopted through 2006. The State Strategy 

identifies new measures to be adopted through 2014; ARB has already acted on some of these 

measures. 

The 2007 State Strategy includes the control measures identified below. Table 2 identifies the 

timeframe for adoption and implementation of these programs. 

Smog Check Improvements The following changes are being developed to improve the 

effectiveness of the smog check program: 
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o A new low pressure evaporative test to examine passenger vehicles for leaks in fuel tanks 

and vapor lines that cause smog-forming emissions; 

o More stringent inspection standards (cutpoints), which are used to determine if a vehicle 

passes or fails; 

o Annual inspections for older and high use vehicles to shorten the time they are emitting 

excess emissions prior to being repaired; 

o The addition of a visible smoke test; and, 

o The addition of inspection requirements for diesel passenger cars and trucks and 

motorcycles, which are currently exempt from Smog Check. 

Expanded Passenger Vehicle Retirement Incentives and other programs retire more highemitting passenger vehicles, especially “off-cycle” vehicles – cars and light trucks that are 

between smog checks inspections. 

Reformulated Gasoline Modifications Modifications to California’s reformulated gasoline 

program will eliminate or offset permeation emissions resulting from the addition of ethanol to 

gasoline blends. 

Cleaner In-Use Heavy-Duty Trucks Modernize diesel trucks and reduce emissions by requiring 

replacement or cleanup of the dirtiest trucks on the road. This critical regulation, which is 

expected to be considered for adoption in 2008, will also include a program for out-of-state 

trucks doing business in California. 

Goods Movement Sources The 2007 State Strategy takes aim at emissions from ships, trucks, 

harbor craft and other sources associated with the growing goods movement sector. ARB has 

already adopted several goods movement emission reduction controls. 

o Harborcraft In November 2007 ARB approved a measure that requires owners of 

commercial harbor craft to either replace old engines with newer, cleaner versions or 

add control technologies to clean up exhaust. 

o Cold Ironing In December 2007, ARB approved a regulation to provide alternative 

power supplies at ports so that ships can use clean fuels, including electricity, instead 

of diesel-fueled auxiliary engines while at dock. 

o Port Trucks In December 2007 ARB approved a measure requiring retrofit or 

replacement of older heavy-duty diesel trucks that service ports or deliver containers 

from ports to nearby transfer facilities. 

o Ship Engines ARB staff is developing a regulation that would require ocean-going 

vessels to use cleaner fuels in ship main and auxiliary engines when they are 

operating near the California coast. 

o Locomotives The State Strategy also calls for reducing emissions from line-haul 

locomotives by replacing and rebuilding existing engines beginning in 2012. This 

measure relies in part on U.S. EPA action to ensure that clean engines are available to 

meet this schedule. 

Construction and Mining Equipment In July 2007, the Board approved a measure which 

regulates existing construction and other industrial equipment. The regulation establishes fleet 

average emission limits and requires older, dirtier engines to be replaced by current models or 

retrofitted with emission control devices. Accelerated clean-up provisions are available to local 
22 AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

districts that provide financial assistance to sources that would be subject to the more stringent 

requirements. 

Agricultural Equipment ARB staff is evaluating the options for modernizing and reducing 

emissions from agricultural equipment, and ARB is expected to consider a regulation in 2009. 

Recreational Boats Existing ARB regulations establish new emission limits for recreational 

boats beginning in 2009. The 2007 State Strategy calls for a more stringent, catalyst-based 

exhaust standard to be phased in by 2013. 

Off-Road Recreational Vehicles The State Strategy includes expanded emission standards for 

off-road recreational vehicles that would reduce exhaust emissions from new vehicles by 50 

percent beginning in 2012, using proven automotive and on-road motorcycle exhaust emission 

reduction technologies. 

Fuel Storage ARB adopted enhanced vapor recovery for above ground storage tanks in June 

2007. Additional evaporative emission standards are proposed for portable outboard marine tank 

engines and refueling gasoline tanks that are usually mounted on a vehicle and used to refuel 

other vehicles. 

Consumer Products ARB staff will consider new approaches such as alternative, market-based 

mechanisms, multi-media labeling programs, and public education as it develops ways to meet 

the State Strategy commitment to further reduce ROG emissions from consumer products. 

Greenhouse Gas Reduction Co-Benefits The California Global Warming Solutions Act of 2006 

(AB 32) requires the adoption of a comprehensive program to reduce greenhouse gas emissions. 

ARB has already started to adopt regulations in response to this requirement. Although the AB 

32 regulations will not directly reduce ozone precursors, many of these regulations are expected 

to have criteria pollutant “co-benefits.” 

Pesticides The Department of Pesticide Regulation’s 2008 Pesticide Plan includes strategies to 

reduce ROG emissions from pesticides through regulation of fumigant pesticide use, regulatory 

standards for registration of liquid pesticides, and strategic partnership agreements implementing 

pest management practices and technologies that use less pesticide product. 
AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

23

Table 2 - Expected Emission Reductions from Proposed New SIP Measures 

Antelope Valley Non Attainment Area -- 2020

Direct

PM2.5

Passenger Vehicles 0.2644 0.4306 0 --

 Smog Check Improvements (BAR) 0.3 0.3 0 --

 Expanded Vehicle Retirement 0 0 0 --

 Modifications to Reformulated Gasoline Program -- 0.1 -- --

Heavy-Duty Trucks 0.6 0 0 --

 Cleaner In-Use Heavy-Duty Trucks 0.6 0 0 --

Goods Movement Sources 1.4 0.2 0.1 --

 Auxiliary Ship Engine Cold Ironing & Clean Technology -- -- -- --

 Cleaner Main Ship Engines and Fuel -- -- -- --

 Port Truck Modernization -- -- -- --

 Accelerated Intro. of Cleaner Line-Haul Locomotives 1.4 0.2 0.1 --

 Clean Up Existing Harbor Craft -- -- -- --

Off-Road Equipment 1.5 0.2 0.1 --

 Cleaner In-Use Off-Road Equipment (over 25hp) 1.5 0.2 0.1 --

 Cleaner In-Use Agricultural Equipment NYQ NYQ NYQ --

Other Off-Road Sources 0 0.4 -- --

 New Emission Standards for Recreational Boats 0 0 -- --

 Expanded Off-Road Rec. Vehicle Emission Standards -- 0.4 -- --

 Additional Evaporative Emission Standards -- NYQ -- --

 Vapor Recovery for Above Ground Storage Tanks -- NYQ -- --

Areaswide Sources -- 0.4 -- --

 Consumer Products Program -- 0.4 -- --

 Pesticides: DPR 2008 Pesticide Plan -- NYQ -- --

Emission Reductions from Proposed New Measures 3.7 1.6 0.2 --

NYQ = Not Yet Quantified. BAR = Bureau of Automotive Repair. DPR = Dept. of Pesticide Regulation

Locomotives measure relies on U.S. EPA rulemaking and industry agreement to accelerate fleet turnover.

Note: Emission reductions reflect the combination impact of regulations and supportive incentive programs.

Proposed New SIP Measures NOx ROG SOx

Local Rule Adoption Schedule 

The rule actions identified in Table 3 below are expected to have some (currently unquantified) 

positive effect on ozone precursor emissions. The State all feasible measures actions are 

analyses that may result in a rule adoption action depending on the outcome of the feasibility 

analysis – the specified date is for completion of the feasibility analysis. 

Table 3 - AVAQMD Rule Adoption Schedule 

Rule Title Rule Nature Adoption Date

Internal Combustion Engines Federal RACT 1/2009 

Fugitive Dust Federal RACT 3/2009 

Agricultural Operations Federal RACT 12/16/2008 
24 AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

Rule Title Rule Nature Adoption Date

Usage of Solvents State All Feasible Measures 12/16/2008 

Boilers, Steam Generators and Process Heaters State All Feasible Measures 12/16/2008 

Turbines State All Feasible Measures 12/16/2008 

Residential Water Heaters State All Feasible Measures 12/16/2008 

Commercial Charboilers State All Feasible Measures 12/16/2008 

Graphic Arts State All Feasible Measures 12/16/2008 

Metal Parts and Product Coatings State All Feasible Measures 12/16/2008 

Spray Booths State All Feasible Measures 12/16/2008 

Wood Flat Stock Coatings State All Feasible Measures 12/16/2008 

Soil Decontamination State All Feasible Measures 12/16/2008 

Solid Waste Landfills State All Feasible Measures 12/16/2008 

Woodworking Operations State All Feasible Measures 12/16/2008 

Composting Operations State All Feasible Measures 12/16/2008 

Residential Wood Burning State All Feasible Measures 12/16/2008 

Contingency Measures 

Failure to attain or make appropriate progress in attaining any ozone standard would not be due 

to local emissions, but would be due to insufficient ozone precursor reductions in the upwind 

regions (primarily the SCAQMD). California’s adopted motor vehicle emission reduction 

program will continue to reduce emissions in the Antelope Valley and upwind regions beyond 

2007, and serves as a contingency measure for this plan. 

Required Progress 

Federal law specifies that each ozone non-attainment area must demonstrate ongoing emission 

reductions relative to the base year (2002). Federal law requires a three percent (3%) per year 

reduction in VOC emissions, and does not allow credit to be taken for certain federal motor 

vehicle control programs (FMVCP). Where both VOC and NOx emissions have been shown to 

contribute to high ozone levels, the Clean Air Act allows NOx emission reductions to be used to 

augment VOC emission reductions in order to demonstrate reasonable further progress. In nonattainment areas that are impacted by transport from other regions, the Federal Clear Air Act also 

allows emissions and emission reduction from those regions to be taken into account when 

assessing reasonable further progress. Air quality modeling, described in Chapter 4, 

demonstrates that emissions from the SCAB contribute to violations of the NAAQS in both the 

Antelope Valley and Mojave Desert portions of the federal non-attainment area (the WMDONA) 

Table 4 demonstrates that the rate of progress projected for the WMDONA meets Federal Clean 

Air Act requirements. The required rate of progress is met in part by substituting NOx reductions 

for VOC reductions at the rate of 1.6 tons of NOx per ton of VOC shortfall. The WMDONA 

consists of the Antelope Valley in Los Angeles County and the Mojave and Victor Valley 

portions of San Bernardino County. The reasonable further progress assessment takes into 

account projected emissions for upwind areas within 100 kilometers of the WMDONA 

(specifically Orange County and the SCAB portions of Los Angeles and San Bernardino 

Counties) as allowed by USEPA guidance. 
AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

25

Table 4 - Reasonable Further Progress for the WMDONA 

2002 2008 2011 2014 2017 2020

Baseline ROG 882.5 651.1 601.9 570.3 551.9 543.5

CA MVCP/RVP Adjustment 0.0 54.4 71.0 84.5 91.5 96.0

RACT Corrections 0 000 0 0

Adjusted 2002 Baseline ROG in milestone year 882.5 828.1 811.4 798.0 791.0 786.5

RFP commitment for ROG reductions from new measures 000 0 0

Required % change since previous milestone year (ROG or 

NOx) compared to 2002

15% 9% 9% 9% 9%

Required % change since 2002 (ROG or NOx)1 15% 24% 33% 42% 51%

Target ROG levels 703.9 616.7 534.6 458.8 385.4

Apparent shortfall in ROG -52.78 -14.73 35.68 93.17 158.17

Apparent shortfall in ROG, % -6.4% -1.8% 4.5% 11.8% 20.1%

ROG shortfall previously provided by NOx substitution, % 0.0% 0.0% 0.0% 4.5% 11.8%

Actual ROG shortfall, % -6.4% -1.8% 4.5% 7.3% 8.3%

Baseline NOx 1123.7 905.0 789.0 696.9 622.9 574.2

CA MVCP Adjustment 0.0 64.8 80.8 93.2 98.7 102.8

Adjusted 2002 Baseline NOx in milestone year 1123.7 1058.8 1042.9 1030.4 1025.0 1020.8

RFP commitment for NOx reductions from new measures 0 000 0 0

Change in NOx since 2002 153.8 253.8 333.6 402.1 446.6

Change in NOx since 2002, % 14.5% 24.3% 32.4% 39.2% 43.8%

NOx reductions since 2002 already used for RFP substitution 

and contingency through last milestone year, % 0.0% 3.0% 3.0% 7.5% 14.8%

NOx reductions since 2002 available for RFP substitution and 

contingency in this milestone year, %

14.5% 21.3% 29.4% 31.8% 29.0%

Change in NOx since 2002 used for ROG substitution in this 

milestone year, % 0.0% 0.0% 4.5% 7.3% 8.3%

Change in NOx since 2002 available for contingency in this 

milestone year, % 3.0% 3.0% 3.0% 3.0% 3.0%

Change in NOx since 2002 surplus after meeting substitution 

and contingency needs in this milestone year, %

11.5% 21.3% 24.9% 24.4% 20.6%

RFP shortfall, if any 0.0% 0.0% 0.0% 0.0% 0.0%

RFP Met? YES YES YES YES YES

Contingency Met? YES YES YES YES YES

1 15% ROG only reduction required from 2002-2008

Western Mojave Desert & Antelope Valley (with transport from Orange, San Bernardino-SCAB and LA-SCAB), summer 

planning, tons per day

Controlled Emission Inventories 

As the AVAQMD is not proposing any additional local control measures with quantified 

emission reductions, the controlled emission inventory is identical to the forecasted emission 

inventory. 

Conformity Budgets 

The forecasted emission inventories presented in this document are the emission budgets for 

general conformity purposes, as no additional control measures with quantified emission 

reductions are proposed. A project subject to the general conformity test must be demonstrated 

to conform with the applicable portion of the forecasted emission inventory. For a project that 

falls between forecasted years, a linearly interpolated inventory may be calculated. For a project 

that falls after 2020, use 2020. 

The forecasted on-road mobile source inventory represents the emission budget for 

transportation conformity purposes, as no transportation control measures are proposed. A 
26 AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

project subject to the transportation conformity test must be demonstrated to conform with the 

forecasted on-road mobile source inventory. The WMDONA on-road mobile source inventory is 

presented below, in addition to the appendices. The portion presented in Table 5 is for 

information only - the AVAQMD is officially adopting the transportation budget for the entire 

Western Mojave Desert ozone non-attainment area as presented in Appendix C. 

Table 5 - Transportation Conformity Budget (AV portion of WMDONA) 

(tons per ozone seasonal day) 

2002 2008 2011 2014 2017 2020

On-Road Mobile VOC 10.11 7.96 7.27 6.26 5.70 5.35

On-Road Mobile NOx 13.99 10.67 9.20 7.39 6.08 5.08
AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

27

CHAPTER 4 – Attainment Demonstration 

Modeling Approach Overview 

Modeling Domain 

Model Inputs 

Modeling Results 

ARB Weight of Evidence Assessment 
28 AVAQMD Federal 8-hour Ozone Attainment Plan 

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AVAQMD Federal 8-hour Ozone Attainment Plan 

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29

ATTAINMENT DEMONSTRATION 

This chapter paraphrases and reiterates information from the most recent SCAQMD/CARB 

ozone model runs, the runs performed for the 2007 SCAQMD AQMP. For further information, 

please refer to Appendix V of that document.4

The Federal Clean Air Act (FCAA) required the use of photochemical air quality modeling to 

evaluate whether a proposed control strategy will result in attainment of the applicable ozone 

standard. Recognizing the uncertainty inherent in large-scale air quality models, recent federal 

guidance has also required an evaluation of supplementary data, known as a weight of evidence 

analysis. A weight of evidence analysis can also be used to support an attainment demonstration 

if photochemical modeling indicates that the control strategy will result in future ozone 

concentration that will approach but not quite reach the standard. 

Modeling Approach Overview 

The Western Mojave Desert ozone non-attainment area, which includes the AVAQMD, is a 

small portion of the complex greater Southern California airshed. Ozone and ozone precursors 

are known to flow (or be transported), under the influence of winds, throughout Southern 

California. The most technically accurate method of evaluating ozone concentrations, ozone 

emissions, and future ozone behavior is through a large modeling project that includes all of the 

affected areas in Southern California (and a portion of northern Mexico). The modeling effort 

has been performed as a joint project by all of the air districts in the region and CARB, with 

SCAQMD and CARB staff and resources doing the primary work. This regional modeling effort 

has allowed the most accurate understanding and prediction of future ozone concentrations for 

Southern California. 

The modeled attainment demonstration in this plan was prepared using photochemical dispersion 

and meteorological tools developed in response to USEPA modeling guidelines, and 

recommendations from air quality modeling experts. The Urban Airshed Model (UAM) is the 

regional modeling system preferred by USEPA and CARB for analyzing ozone non-attainment 

areas. The UAM predicts future ambient ozone concentrations under historical conditions that 

led to high ambient ozone concentrations. These conditions are typically multi-day ‘episodes’ in 

which the State and Federal ozone standards were exceeded. The UAM also evaluates ozone 

precursor emissions, local and regional meteorology, and regional topography to calculate ozone 

concentrations. These calculations are performed on an hourly basis throughout the modeled 

episode, thus allowing the UAM to stimulate changing conditions (i.e. night, day and wind). 

Meteorological fields were generated using the MM5 prognostic meteorological model, and the 

required modeling emissions inventories were developed by CARB and SCAQMD staff. The 

ozone air quality modeling utilized the Comprehensive Air Quality Model with Extensions 

(CAMx) model, with initial and boundary conditions based on estimates of clean-air 

concentrations. Analysis of the model outputs included the estimation of 1-hour and 8-hour 

ozone concentrations for each ozone monitoring site within the domain, as well as statistical 

 

4

“Final 2007 Appendix V - Modeling and Attainment Demonstrations,” SCAQMD, June 2007 
30 AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

measures comparing observed and stimulated ozone concentrations. These analyses were used 

to evaluate model performance by sub-region within the domain. 

Modeling Domain 

The modeling domain is based on the domain defined for the 1997 Southern California Ozone 

Study and includes the South Coast Air Basin and the surrounding coastal, desert and mountain 

areas, including the AVAQMD. This model domain includes the upwind sources within 

SCAQMD, which are responsible for the overwhelming ozone transport into the AVAQMD. 

The northern boundary of the model extends into Santa Barbara and Kern counties, while the 

southern boundary extends in Mexico. The eastern boundary of the modeling domain extends 

into the desert portions of San Bernardino and Riverside counties, while the western boundary 

extends into the Pacific Ocean. The domain horizontal grid is 116 by 80 cells, with a cell 

resolution of five kilometers. 

Model Inputs 

SCAQMD performed the UAM attainment demonstration using data maintained by CARB and 

AVAQMD. The emissions inventory used for the UAM is consistent with the emissions 

inventory presented in the appendices to this document. 

Modeling Results 

Future years are simulated twice using the UAM: first, using the uncontrolled emissions 

inventory; and second, using a reduced emissions inventory controlled by the proposed ozone 

control strategy. Comparing the uncontrolled and controlled ambient ozone concentrations 

identifies the effectiveness of the proposed ozone control strategy. Attainment year ambient 

ozone concentrations using the reduced emissions inventory controlled by the proposed ozone 

control strategy should achieve the ozone standard. 

As required by federal guidance, a relative reduction factor (RRF) approach was used in 

projecting future design values. The RRF reflects the ratio between the future year model 

prediction (in this case the end of 2020) and the reference year model prediction (in this case 

2002). A reference or base year design value is then multiplied by the RRF to project a future 

year design value. The modeling satisfies the minimum five episode requirement for use in 

developing a site-specific RRF for most sites, as recommended by the USEPA guidance for 

modeling 8-hour ozone design values. 

Table 6 presents the photochemical ozone modeling results for the FONA, including the 

AVAQMD site. 
AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

31

Table 6 - 2020 Federal Ozone Attainment Demonstration 

Baseline (2001-2003) 2012 2017 2020

Lancaster 100.7 86.5 79.7 74.0

Phelan 104.7 92.6 86.7 80.5

Victorville 98.3 88.0 77.0 74.4

Hesperia 106.3 95.7 88.7 76.5

Barstow 87.6 79.7 73.2 79.5

Twentynine Palms 86.7 77.3 65.8 82.2

Modeled

(all values ozone in ppb)

The modeling results show that the AVAQMD will not attain the 8-hour ozone NAAQS (84 ppb) 

by the 2012 attainment deadline for Serious ozone non-attainment areas, but that the AVAQMD 

will attain by the 2020 deadline for Severe-17 non-attainment areas. 

ARB Weight of Evidence Assessment 

Federal modeling guidelines also require non-attainment areas to determine whether other 

evidence, such as evaluations of air quality and emission trends, support the modeled attainment 

demonstration. USEPA’s ozone modeling guidance also indicates that when photochemical 

modeling projects attainment year concentrations of between 0.082 and 0.087 ppm, the State 

may conduct further analyses of the model outcomes and consider other evidence such as 

emissions and air quality trends data. If the weight of this evidence supports a finding that the 

proposed control program will result in attainment by the statutory deadline, the State may 

consider this evidence in determining whether the proposed control program will result in 

attainment. 

CARB has performed a detailed weight of evidence assessment for the attainment demonstration 

of the AVAQMD portion of the Western Mojave Desert federal ozone nonattainment area. This 

analysis supports the determination that the AVAQMD portion will attain the Federal 8-hour 

ozone standard by the 2020 deadline for Severe-17 areas on the basis of reduced transported air 

pollution from upwind areas. Because the photochemical modeling projected a high value of 

88.7 ppm in 2017, the weight of evidence analysis cannot be used to support a projection of 

attainment by 2017. The ARB Weight of Evidence assessment is presented in Appendix F. 
32 AVAQMD Federal 8-hour Ozone Attainment Plan 

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AVAQMD Federal 8-hour Ozone Attainment Plan 

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33

Appendices 

A - Base Year Emission Inventory 

B - Future Year Emission Inventories 

C - Transportation Conformity Budgets 

D - Annual Ambient Monitoring Data Summary 

E - ARB Weight of Evidence Assessment 
34 AVAQMD Federal 8-hour Ozone Attainment Plan 

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AVAQMD Federal 8-hour Ozone Attainment Plan 

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A-1

APPENDIX A - BASE YEAR EMISSION INVENTORY 

All emissions are presented in tons per ozone seasonal day for the 2002 base year 

SUBCATEGORY NOx VOC

Stationary

MANUFACTURING AND INDUSTRIAL 1.13 0.07

SERVICE AND COMMERCIAL 0.37 0.05

OTHER (FUEL COMBUSTION) 0.20 0.02

LANDFILLS 0.00 0.02

OTHER (WASTE DISPOSAL) 0.00 0.02

LAUNDERING 0.00 0.00

DEGREASING 0.00 2.28

COATINGS AND RELATED PROCESS SOLVENTS 0.00 0.80

ADHESIVES AND SEALANTS 0.00 0.06

OTHER (CLEANING AND SURFACE COATINGS) 0.00 0.00

PETROLEUM REFINING 0.00 0.00

PETROLEUM MARKETING 0.00 2.58

OTHER (PETROLEUM PRODUCTION AND MARKETING) 0.00 0.00

CHEMICAL 0.00 0.00

FOOD AND AGRICULTURE 0.00 0.01

MINERAL PROCESSES 0.13 0.05

METAL PROCESSES 0.00 0.00

WOOD AND PAPER 0.00 0.00

OTHER (INDUSTRIAL PROCESSES) 0.19 0.08

Stationary Subtotal 2.03 6.04

Area-Wide

CONSUMER PRODUCTS 0.00 2.31

ARCHITECTURAL COATINGS AND RELATED PROCESS SOLVENTS 0.00 1.26

PESTICIDES/FERTILIZERS 0.00 0.20

ASPHALT PAVING / ROOFING 0.00 0.09

RESIDENTIAL FUEL COMBUSTION 0.25 0.04

FARMING OPERATIONS 0.00 0.13

CONSTRUCTION AND DEMOLITION 0.00 0.00

PAVED ROAD DUST 0.00 0.00

UNPAVED ROAD DUST 0.00 0.00

FUGITIVE WINDBLOWN DUST 0.00 0.00

FIRES 0.00 0.01

MANAGED BURNING AND DISPOSAL 0.12 0.31

COOKING 0.00 0.05

Area-Wide Subtotal 0.37 4.38

On-Road Mobile

LIGHT DUTY PASSENGER (LDA) 3.03 4.64

LIGHT DUTY TRUCKS - 1 (LDT1) 0.89 1.16

LIGHT DUTY TRUCKS - 2 (LDT2) 2.22 1.78

MEDIUM DUTY TRUCKS (MDV) 1.39 1.02

LIGHT HEAVY DUTY GAS TRUCKS - 1 (LHDV1) 0.57 0.39

LIGHT HEAVY DUTY GAS TRUCKS - 2 (LHDV2) 0.04 0.05

MEDIUM HEAVY DUTY GAS TRUCKS (MHDV) 0.07 0.09

HEAVY HEAVY DUTY GAS TRUCKS (HHDV) 0.09 0.03

LIGHT HEAVY DUTY DIESEL TRUCKS - 1 (LHDV1) 0.01 0.00

LIGHT HEAVY DUTY DIESEL TRUCKS - 2 (LHDV2) 0.16 0.00

MEDIUM HEAVY DUTY DIESEL TRUCKS (MHDV) 0.47 0.01

HEAVY HEAVY DUTY DIESEL TRUCKS (HHDV) 4.46 0.29

MOTORCYCLES (MCY) 0.09 0.58

HEAVY DUTY DIESEL URBAN BUSES (UB) 0.07 0.00

HEAVY DUTY GAS URBAN BUSES (UB) 0.00 0.00

SCHOOL BUSES (SB) 0.21 0.02

OTHER BUSES (OB) 0.06 0.01

MOTOR HOMES (MH) 0.16 0.04

On-Road Subtotal 13.99 10.11

Other Mobile

AIRCRAFT 0.60 0.71

TRAINS 2.34 0.18

RECREATIONAL BOATS 0.03 0.23

OFF-ROAD RECREATIONAL VEHICLES 0.01 0.35

OFF-ROAD EQUIPMENT 12.18 2.13

FARM EQUIPMENT 0.05 0.01

FUEL STORAGE AND HANDLING 0.00 0.48

SHIPS AND COMMERCIAL BOATS 0.00 0.00

Other Mobile Subtotal 15.21 4.09

Grand Total 31.60 24.62
A-2 AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

Detailed Point Sources for 2002 (all emissions in tons per year) 

Source VOC NOx 

Boeing NASA (Aerospace) 2.6 0.6 

Lockheed Martin (Aerospace) 22.9 10.1 

Northrop Grumman (Aerospace) 12.7 82 

Antelope Valley Aggregate (Batch Plant) 3.7 46.0 

Asphalt Construction Co (Batch Plant) 0.8 1.5 

Calmat Vulcan 6851 Ave T (Batch Plant) 4.5 52.0 

Calmat Vulcan 7107 Ave T (Batch Plant) 0.9 1.9 

Granite Construction (Batch Plant) 0.0 0.1 

Hi-Grade Materials Ave T (Batch Plant) 0.1 0.0 

Rexhall Industries (Fiberglass) 20.0 0.0 

Antelope Valley Healthcare System (Institution) 3.5 3.4 

Ca State Prison - Los Angeles County (Institution) 0.4 0.2 

LA County Sheriff W 60th (Institution) 0.2 2.6 

Magna Color (Misc Coating/Manuf) 0.7 0.0 

Mountain High Combined (Misc Diesel Use) 9.6 48.0 

Verizon (Misc Diesel Use) 0.0 0.6 

LA County Palmdale Water Reclamation Plant 0.6 1.2 

LA County Sanitation District #14 3.5 1.0 

Lancaster Landfill, Waste Management 0.5 0.1 

Total Point Sources 2002 (tons per year): 87.2 251.3 

Total Point Sources 2002 (tons per day): 0.24 0.69 
AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

B-1

APPENDIX B - FUTURE YEAR EMISSION INVENTORIES 

(all emissions in tons per ozone seasonal day unless otherwise indicated) 

VOC: 

ROG - Antelope Valley - SUMMER PLANNING INVENTORY -- ADJUSTED FOR MEASURES THROUGH 31 DEC 2006

SUBCATEGORY 2002 2008 2011 2014 2017 2020

Stationary

MANUFACTURING AND INDUSTRIAL 0.07 0.08 0.08 0.08 0.09 0.09

SERVICE AND COMMERCIAL 0.05 0.05 0.05 0.05 0.05 0.05

OTHER (FUEL COMBUSTION) 0.02 0.02 0.01 0.01 0.01 0.01

LANDFILLS 0.02 0.02 0.02 0.02 0.02 0.02

OTHER (WASTE DISPOSAL) 0.02 0.03 0.03 0.03 0.04 0.04

LAUNDERING 0.00 0.00 0.00 0.00 0.00 0.00

DEGREASING 2.28 2.38 2.46 2.54 2.60 2.67

COATINGS AND RELATED PROCESS SOLVENTS 0.80 0.86 0.93 1.00 1.07 1.12

ADHESIVES AND SEALANTS 0.06 0.05 0.05 0.05 0.05 0.04

OTHER (CLEANING AND SURFACE COATINGS) 0.00 0.00 0.00 0.00 0.00 0.00

PETROLEUM REFINING 0.00 0.00 0.00 0.00 0.00 0.00

PETROLEUM MARKETING 2.58 2.84 2.96 3.10 3.24 3.38

OTHER (PETROLEUM PRODUCTION AND MARKETING) 0.00 0.00 0.00 0.00 0.00 0.00

CHEMICAL 0.00 0.00 0.00 0.00 0.00 0.00

FOOD AND AGRICULTURE 0.01 0.01 0.01 0.01 0.01 0.01

MINERAL PROCESSES 0.05 0.05 0.06 0.06 0.06 0.06

METAL PROCESSES 0.00 0.00 0.00 0.00 0.00 0.00

WOOD AND PAPER 0.00 0.00 0.00 0.00 0.00 0.00

OTHER (INDUSTRIAL PROCESSES) 0.08 0.09 0.09 0.10 0.11 0.11

Stationary Subtotal 6.04 6.49 6.76 7.06 7.34 7.62

Area-Wide

CONSUMER PRODUCTS 2.31 2.31 2.54 2.80 3.05 3.31

ARCHITECTURAL COATINGS AND RELATED PROCESS SOLVENTS 1.26 1.10 1.13 1.15 1.18 1.20

PESTICIDES/FERTILIZERS 0.20 0.31 0.31 0.31 0.31 0.31

ASPHALT PAVING / ROOFING 0.09 0.09 0.09 0.09 0.09 0.09

RESIDENTIAL FUEL COMBUSTION 0.04 0.04 0.04 0.04 0.04 0.04

FARMING OPERATIONS 0.13 0.13 0.13 0.13 0.13 0.13

CONSTRUCTION AND DEMOLITION 0.00 0.00 0.00 0.00 0.00 0.00

PAVED ROAD DUST 0.00 0.00 0.00 0.00 0.00 0.00

UNPAVED ROAD DUST 0.00 0.00 0.00 0.00 0.00 0.00

FUGITIVE WINDBLOWN DUST 0.00 0.00 0.00 0.00 0.00 0.00

FIRES 0.01 0.01 0.01 0.01 0.01 0.01

MANAGED BURNING AND DISPOSAL 0.31 0.34 0.36 0.38 0.40 0.42

COOKING 0.05 0.05 0.05 0.06 0.06 0.06

Area-Wide Subtotal 4.38 4.38 4.65 4.97 5.27 5.58

On-Road Mobile

LIGHT DUTY PASSENGER (LDA) 4.64 3.24 2.79 2.18 1.82 1.58

LIGHT DUTY TRUCKS - 1 (LDT1) 1.16 0.84 0.70 0.56 0.45 0.38

LIGHT DUTY TRUCKS - 2 (LDT2) 1.78 1.58 1.56 1.40 1.32 1.25

MEDIUM DUTY TRUCKS (MDV) 1.02 0.86 0.87 0.82 0.78 0.75

LIGHT HEAVY DUTY GAS TRUCKS - 1 (LHDV1) 0.39 0.17 0.15 0.13 0.13 0.13

LIGHT HEAVY DUTY GAS TRUCKS - 2 (LHDV2) 0.05 0.02 0.02 0.02 0.02 0.02

MEDIUM HEAVY DUTY GAS TRUCKS (MHDV) 0.09 0.04 0.03 0.02 0.01 0.01

HEAVY HEAVY DUTY GAS TRUCKS (HHDV) 0.03 0.02 0.02 0.01 0.01 0.01

LIGHT HEAVY DUTY DIESEL TRUCKS - 1 (LHDV1) 0.00 0.00 0.00 0.00 0.00 0.00

LIGHT HEAVY DUTY DIESEL TRUCKS - 2 (LHDV2) 0.00 0.00 0.00 0.00 0.00 0.00

MEDIUM HEAVY DUTY DIESEL TRUCKS (MHDV) 0.01 0.01 0.01 0.01 0.01 0.01

HEAVY HEAVY DUTY DIESEL TRUCKS (HHDV) 0.29 0.26 0.22 0.18 0.15 0.13

MOTORCYCLES (MCY) 0.58 0.85 0.86 0.90 0.97 1.05

HEAVY DUTY DIESEL URBAN BUSES (UB) 0.00 0.00 0.00 0.00 0.00 0.00

HEAVY DUTY GAS URBAN BUSES (UB) 0.00 0.00 0.00 0.00 0.00 0.00

SCHOOL BUSES (SB) 0.02 0.02 0.01 0.01 0.01 0.01

OTHER BUSES (OB) 0.01 0.02 0.01 0.01 0.01 0.01

MOTOR HOMES (MH) 0.04 0.03 0.02 0.02 0.01 0.01

On-Road Subtotal 10.11 7.96 7.27 6.26 5.70 5.35

Other Mobile

AIRCRAFT 0.71 0.85 0.94 1.05 1.15 1.25

TRAINS 0.18 0.18 0.18 0.19 0.20 0.20

RECREATIONAL BOATS 0.23 0.21 0.19 0.18 0.17 0.17

OFF-ROAD RECREATIONAL VEHICLES 0.35 0.50 0.55 0.60 0.67 0.74

OFF-ROAD EQUIPMENT 2.13 1.85 1.67 1.53 1.41 1.33

FARM EQUIPMENT 0.01 0.01 0.01 0.00 0.00 0.00

FUEL STORAGE AND HANDLING 0.48 0.31 0.24 0.20 0.17 0.15

SHIPS AND COMMERCIAL BOATS 0.00 0.00 0.00 0.00 0.00 0.00

Other Mobile Subtotal 4.09 3.90 3.78 3.75 3.76 3.84

Grand Total 24.62 22.72 22.46 22.04 22.07 22.38
B-2 AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

NOx: 

NOX - Antelope Valley - SUMMER PLANNING INVENTORY -- ADJUSTED FOR MEASURES THROUGH 31 DEC 2006

SUBCATEGORY 2002 2008 2011 2014 2017 2020

Stationary

MANUFACTURING AND INDUSTRIAL 1.13 1.22 1.26 1.32 1.38 1.43

SERVICE AND COMMERCIAL 0.37 0.39 0.40 0.40 0.41 0.41

OTHER (FUEL COMBUSTION) 0.20 0.18 0.17 0.16 0.15 0.15

LANDFILLS 0.00 0.00 0.00 0.00 0.00 0.00

OTHER (WASTE DISPOSAL) 0.00 0.00 0.00 0.00 0.00 0.00

LAUNDERING 0.00 0.00 0.00 0.00 0.00 0.00

DEGREASING 0.00 0.00 0.00 0.00 0.00 0.00

COATINGS AND RELATED PROCESS SOLVENTS 0.00 0.00 0.00 0.00 0.00 0.00

ADHESIVES AND SEALANTS 0.00 0.00 0.00 0.00 0.00 0.00

OTHER (CLEANING AND SURFACE COATINGS) 0.00 0.00 0.00 0.00 0.00 0.00

PETROLEUM REFINING 0.00 0.00 0.00 0.00 0.00 0.00

PETROLEUM MARKETING 0.00 0.00 0.00 0.00 0.00 0.00

OTHER (PETROLEUM PRODUCTION AND MARKETING) 0.00 0.00 0.00 0.00 0.00 0.00

CHEMICAL 0.00 0.00 0.00 0.00 0.00 0.00

FOOD AND AGRICULTURE 0.00 0.00 0.00 0.00 0.00 0.00

MINERAL PROCESSES 0.13 0.14 0.15 0.16 0.18 0.19

METAL PROCESSES 0.00 0.00 0.00 0.00 0.00 0.00

WOOD AND PAPER 0.00 0.00 0.00 0.00 0.00 0.00

OTHER (INDUSTRIAL PROCESSES) 0.19 0.20 0.21 0.22 0.24 0.25

Stationary Subtotal 2.03 2.14 2.19 2.28 2.35 2.42

Area-Wide

CONSUMER PRODUCTS 0.00 0.00 0.00 0.00 0.00 0.00

ARCHITECTURAL COATINGS AND RELATED PROCESS SOLVENTS 0.00 0.00 0.00 0.00 0.00 0.00

PESTICIDES/FERTILIZERS 0.00 0.00 0.00 0.00 0.00 0.00

ASPHALT PAVING / ROOFING 0.00 0.00 0.00 0.00 0.00 0.00

RESIDENTIAL FUEL COMBUSTION 0.25 0.25 0.25 0.25 0.26 0.26

FARMING OPERATIONS 0.00 0.00 0.00 0.00 0.00 0.00

CONSTRUCTION AND DEMOLITION 0.00 0.00 0.00 0.00 0.00 0.00

PAVED ROAD DUST 0.00 0.00 0.00 0.00 0.00 0.00

UNPAVED ROAD DUST 0.00 0.00 0.00 0.00 0.00 0.00

FUGITIVE WINDBLOWN DUST 0.00 0.00 0.00 0.00 0.00 0.00

FIRES 0.00 0.00 0.00 0.00 0.00 0.00

MANAGED BURNING AND DISPOSAL 0.12 0.13 0.14 0.15 0.16 0.16

COOKING 0.00 0.00 0.00 0.00 0.00 0.00

Area-Wide Subtotal 0.37 0.38 0.39 0.40 0.41 0.42

On-Road Mobile

LIGHT DUTY PASSENGER (LDA) 3.03 1.87 1.58 1.18 0.93 0.75

LIGHT DUTY TRUCKS - 1 (LDT1) 0.89 0.59 0.49 0.38 0.29 0.23

LIGHT DUTY TRUCKS - 2 (LDT2) 2.22 1.59 1.43 1.17 0.99 0.85

MEDIUM DUTY TRUCKS (MDV) 1.39 1.05 0.96 0.80 0.69 0.58

LIGHT HEAVY DUTY GAS TRUCKS - 1 (LHDV1) 0.57 0.28 0.26 0.25 0.25 0.25

LIGHT HEAVY DUTY GAS TRUCKS - 2 (LHDV2) 0.04 0.04 0.04 0.04 0.04 0.04

MEDIUM HEAVY DUTY GAS TRUCKS (MHDV) 0.07 0.04 0.04 0.03 0.03 0.02

HEAVY HEAVY DUTY GAS TRUCKS (HHDV) 0.09 0.07 0.06 0.05 0.04 0.03

LIGHT HEAVY DUTY DIESEL TRUCKS - 1 (LHDV1) 0.01 0.20 0.16 0.14 0.12 0.11

LIGHT HEAVY DUTY DIESEL TRUCKS - 2 (LHDV2) 0.16 0.15 0.12 0.10 0.09 0.07

MEDIUM HEAVY DUTY DIESEL TRUCKS (MHDV) 0.47 0.41 0.34 0.27 0.22 0.17

HEAVY HEAVY DUTY DIESEL TRUCKS (HHDV) 4.46 3.68 3.03 2.30 1.74 1.35

MOTORCYCLES (MCY) 0.09 0.18 0.20 0.21 0.23 0.25

HEAVY DUTY DIESEL URBAN BUSES (UB) 0.07 0.06 0.06 0.06 0.06 0.06

HEAVY DUTY GAS URBAN BUSES (UB) 0.00 0.00 0.00 0.00 0.00 0.00

SCHOOL BUSES (SB) 0.21 0.24 0.24 0.23 0.21 0.20

OTHER BUSES (OB) 0.06 0.08 0.07 0.07 0.06 0.05

MOTOR HOMES (MH) 0.16 0.14 0.13 0.11 0.09 0.07

On-Road Subtotal 13.99 10.67 9.20 7.39 6.08 5.08

Other Mobile

AIRCRAFT 0.60 0.72 0.79 0.88 0.97 1.05

TRAINS 2.34 1.78 1.36 1.45 1.56 1.68

RECREATIONAL BOATS 0.03 0.05 0.05 0.05 0.05 0.06

OFF-ROAD RECREATIONAL VEHICLES 0.01 0.01 0.01 0.01 0.01 0.02

OFF-ROAD EQUIPMENT 12.18 10.40 9.12 7.69 6.32 5.23

FARM EQUIPMENT 0.05 0.04 0.03 0.03 0.02 0.02

FUEL STORAGE AND HANDLING 0.00 0.00 0.00 0.00 0.00 0.00

SHIPS AND COMMERCIAL BOATS 0.00 0.00 0.00 0.00 0.00 0.00

Other Mobile Subtotal 15.21 13.00 11.37 10.12 8.93 8.05

Grand Total 31.60 26.18 23.16 20.19 17.78 15.97
AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

C-1

APPENDIX C - TRANSPORTATION CONFORMITY BUDGETS 

Antelope Valley - Western Mojave Desert Nonattainment Area

Transportation Conformity Budgets

Summer Planning Emissions in Tons per Day*

2008

ROG NOx

On-Road Emissions from 

EMFAC2007 22.7 82.0

Adjustments to Baseline* 0.0 -4.4

Net Inventory 22.63 77.56

Conformity Budget** 23 78

* Reductions from adopted rules not

 reflected in EMFAC

** Budget is obtained by rounding up

 to the nearest ton.

Antelope Valley - Western Mojave Desert Nonattainment Area

Transportation Conformity Budgets

Summer Planning Emissions in Tons per Day*

2011

ROG NOx

On-Road Emissions from 

EMFAC2007 19.8 70.5

Adjustments to Baseline* -0.1 -4.4

Net Inventory 19.7 66.1

Conformity Budget** 20 67

* Reductions from adopted rules not

 reflected in EMFAC

** Budget is obtained by rounding up from two significant figures

 to the nearest ton.
C-2 AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

Antelope Valley - Western Mojave Desert Nonattainment Area

Transportation Conformity Budgets

Summer Planning Emissions in Tons per Day*

2014

ROG NOx

On-Road Emissions from 

EMFAC2007 16.6 54.9

Adjustments to Baseline* -0.1 -4.1

State Strategy Reductions -3.4 -15.3

Net Inventory 13.0 35.5

Conformity Budget** 14 36

* Reductions from adopted rules not

 reflected in EMFAC

** Budget is obtained by rounding up from two significant figures

 to the nearest ton.

Antelope Valley - Western Mojave Desert Nonattainment Area

Transportation Conformity Budgets

Summer Planning Emissions in Tons per Day*

2017

ROG NOx

On-Road Emissions from 

EMFAC2007 14.5 43.1

Adjustments to Baseline* -0.1 -3.9

State Strategy Reductions -2.5 -14.1

Net Inventory 11.9 25.1

Conformity Budget** 12 26

* Reductions from adopted rules not

 reflected in EMFAC

** Budget is obtained by rounding up from two significant figures

 to the nearest ton.
AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

C-3

Antelope Valley - Western Mojave Desert Nonattainment Area

Transportation Conformity Budgets

Summer Planning Emissions in Tons per Day*

2020

ROG NOx

On-Road Emissions from 

EMFAC2007 13.2 35.4

Adjustments to Baseline* -0.1 -3.7

State Strategy Reductions -1.7 -7.4

Net Inventory 11.4 24.2

Conformity Budget** 12 25

* Reductions from adopted rules not

 reflected in EMFAC

** Budget is obtained by rounding up from two significant figures

 to the nearest ton.
C-4 AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

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AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

D-1

APPENDIX D - ANNUAL AMBIENT MONITORING DATA SUMMARY 

Maximum Design Value Trend

1990 0.15 0.14

1991 0.14 0.14

1992 0.17 0.16

1993 0.16 0.16

1994 0.14 0.16

1995 0.14 0.141

1996 0.13 0.138

1997 0.12 0.129

1998 0.16 0.137

1999 0.10 0.137

2000 0.14 0.139

2001 0.15 0.128

2002 0.16 0.128

2003 0.16 0.13

2004 0.12 0.13

2005 0.13 0.127

2006 0.13 0.123

Max 1-Hr Ozone (ppm)

Maximum Design Value Trend

1990 0.106 0.105

1991 0.111 0.105

1992 0.137 0.11

1993 0.127 0.113

1994 0.112 0.113

1995 0.112 0.108

1996 0.104 0.103

1997 0.101 0.098

1998 0.118 0.097

1999 0.083 0.089

2000 0.117 0.092

2001 0.102 0.091

2002 0.107 0.100

2003 0.120 0.100

2004 0.101 0.100

2005 0.10 0.098

2006 0.11 0.096

Max 8-Hour Ozone (ppm)
E-2 AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

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AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

E-1

APPENDIX E - ARB WEIGHT OF EVIDENCE ASSESSMENT 

(prepared by CARB staff) 
E-2 AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

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AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

E-3

Antelope Valley Weight of Evidence Assessment 

Introduction

For ozone planning purposes, the U.S. EPA has combined portions of Los Angeles and 

San Bernardino counties and designated them as the Western Mojave 8-Hour Ozone 

Nonattainment Area. The Nonattainment Area includes the northeast portion of 

Los Angeles County and the southwest portion of San Bernardino County, both of which 

are in the Mojave Desert Air Basin (refer to Figure 1). These two areas are managed by 

two separate jurisdictions. The Antelope Valley Air Quality Management District has 

jurisdiction over the Los Angeles County portion of the Nonattainment Area, while the 

Mojave Desert Air Quality Management District has jurisdiction over the San Bernardino 

County portion of the Nonattainment Area. This Weight of Evidence evaluation covers 

the Los Angeles County portion of the Nonattainment Area which is referred to as the 

Antelope Valley Planning Area in this document. 

Figure 1: Antelope Valley Planning Area and Surrounding Region 
E-4 AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

The Antelope Valley Planning Area (Antelope Valley) is currently classified as a 

Moderate nonattainment area for the federal 8-hour ozone standard and has a nominal 

attainment deadline of June 15, 2010. However, air quality analyses, as well as 

photochemical modeling completed by the South Coast Air Quality Management District 

(South Coast District), indicate it is unlikely that Antelope Valley will attain by 2010, as 

required for Moderate areas. 

Ozone air quality in the Antelope Valley can be significantly impacted by transport from 

both the South Coast Air Basin (South Coast) and the San Joaquin Valley Air Basin 

(San Joaquin Valley). As a result, attainment projections for Antelope Valley must 

consider not only local emissions, but also the impact of transported emissions and 

pollutants. An additional consideration for the Antelope Valley is its inclusion as part of 

a larger ozone nonattainment area. As mentioned previously, for federal planning 

purposes, the Antelope Valley and the southwestern portion of San Bernardino County 

are considered together as the Western Mojave 8-Hour Ozone Nonattainment Area 

(refer to Figure 1). Because the San Bernardino County portion of the Nonattainment 

Area has a higher design value, it dictates the attainment date for the entire region. 

The proposed South Coast, San Joaquin Valley, and statewide emissions reduction 

strategies will lower ozone concentrations in both the Antelope Valley and southwestern 

San Bernardino County over the next several years. However, the expected level of 

emissions reductions will fall short of those needed to reach attainment in either area by 

2010, as currently required. Therefore, both areas are requesting a reclassification. 

Photochemical modeling results show that the entire Western Mojave Ozone 

Nonattainment Area could attain by the 2021 deadline for a Severe-17 nonattainment 

area. Therefore, both districts are requesting a reclassification to Severe-17, with an 

attainment date of June 15, 2021. Although this later attainment date will apply 

throughout the entire Nonattainment Area, the Antelope Valley portion should reach 

attainment before that date. 

U.S. EPA Attainment Demonstration Requirements

The attainment demonstration portion of a SIP consists of the analyses used to 

determine whether a proposed control strategy provides the emissions reductions 

needed to meet the NAAQS by the attainment year. This attainment demonstration 

includes photochemical modeling, which predicts that projected emissions controls will 

result in an 8-hour ozone design value of 0.082 parts per million (ppm) for the Western 

Mojave Ozone Nonattainment Area by the end of 2020 (note: because the design value 

is based on a 3-year average, an area must have a design value that meets the 

standard at the end of the year prior to the attainment year; for example, an area with a 

June 15, 2021 attainment date must have a design value that meets the standard at the 

end of 2020). Because of the uncertainties inherent in photochemical modeling, the 

U.S. EPA allows states to supplement the modeling results with a “Weight of Evidence” 

(WOE) demonstration when the model predicts ozone levels of 0.082 ppm to 

0.087 ppm. 
AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

E-5

As mentioned earlier, ozone concentrations and design values for the Antelope Valley 

are lower than those for the San Bernardino County portion of the Nonattainment Area. 

However, because these two areas are considered a single nonattainment area, the site 

with the highest design value dictates the region’s attainment date. Photochemical 

modeling for the San Bernardino County portion of the Nonattainment Area does not 

show attainment until the end of 2020. However results for Lancaster, the only 

monitoring site in the Antelope Valley, show attainment before then, with a design value 

of 0.08 ppm at the end of 2017 and 0.074 ppm at the end of 2020. 

The following assessment focuses on the Antelope Valley portion of the Nonattainment 

Area and comprises the WOE evaluation as of March 2008. It provides a set of 

analyses that include consideration of measured air quality, as well as evaluation of 

other air quality indicators and emissions. The scope of the WOE analysis is different 

for each nonattainment area. The level of detail appropriate for a particular area 

depends upon the complexity of the air quality problem, how far into the future the 

attainment deadline is, and the amount of data and modeling available. Because all 

analysis methods have inherent strengths and weaknesses, examining an air quality 

problem in a variety of ways helps offset the limitations and uncertainties that are 

inherent in each particular method. 

Physical Context

The Antelope Valley Planning Area comprises the northeast portion of Los Angeles 

County and is located in the Mojave Desert Air Basin. As shown in Figure 1, the region 

lies generally north of the San Gabriel Mountains and east of the Tehachapi Mountains. 

Covering approximately 1460 square miles, the triangular shaped Antelope Valley is 

one of the smaller planning areas in California. However, for federal purposes, it is 

included with a portion of San Bernardino County as part of the Mojave Desert Ozone 

Nonattainment Area (refer to Figure 1). 

Most of the Antelope Valley is classified as high desert, although small portions extend 

into the San Gabriel Mountains. Elevations range from 2,300 to over 8,000 feet, and 

annual precipitation averages 7 inches in the desert portions of the Antelope Valley to 

over 20 inches in the mountain areas. At Lancaster, summer daily maximum 

temperatures average 96 degrees Fahrenheit, while winter daily maximum 

temperatures average 57 degrees. 

The Antelope Valley has a total population of about 320,000 (2006 estimate). More 

than 280,000 people live in the cities of Lancaster and Palmdale (2005 estimate). The 

Antelope Valley is part of an important transportation corridor linking the eastern and 

southern portions of California. Highway 14 is the major roadway carrying commuter 

and truck traffic through the Antelope Valley on its way in and out of southern California.
E-6 AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

Transport Impacts

As mentioned earlier, ozone concentrations in the Antelope Valley are impacted by 

transport. Therefore, transport must be considered in evaluating the prospects for 

attainment. Prevailing winds can blow emissions and pollutants from the South Coast 

into the Antelope Valley. During the spring through fall ozone season, Soledad Canyon 

on the eastern edge of the San Gabriel Mountains is the major outlet for airflow from the 

Santa Clarita and San Fernando Valley areas in the South Coast to the Antelope Valley. 

State Highway 14 from Santa Clarita parallels the general flow of air into the area. 

Emissions and pollutants are also transported from the southern San Joaquin Valley, 

through the Tehachapi Mountains southeast of Bakersfield, and into the Antelope 

Valley. 

Previous ARB transport assessments concluded that during 1-hour State ozone 

exceedances, the transport contribution from South Coast, as well as from San Joaquin 

Valley to the Lancaster area can be overwhelming (ARB 1990).5 Although the transport 

impacts can be overwhelming, the frequency of the impacts has not been determined. 

However, more recent analyses indicate that ozone exceedances in the Antelope Valley 

continue to be transport impacted. Areas impacted by transport generally show ozone 

concentrations peaking in the late afternoon or evening hours. The 24-hour ozone 

profile for Lancaster (refer to Figure 2) shows this later peak, indicating that transport 

continues to be an important contributor to high ozone concentrations in this area. 

Recent photochemical modeling completed for the Mojave Desert Ozone Nonattainment 

Area also evaluated the impact of transported emissions on air quality in the area. In 

general, results showed that without transport, emissions from within the Nonattainment 

Area would likely not be sufficient to generate an exceedance of the federal 8-hour 

ozone standard in future years. 

The overall long-term trend in the design value for Lancaster is downward. As shown in 

Figure 3, the Lancaster trend is generally similar to the trends for both Santa Clarita in 

the South Coast and Edison in the San Joaquin Valley. The similarity of the trend lines 

provides another indication that ozone in the Antelope Valley is linked to the South 

Coast, as well as to the San Joaquin Valley, and that transport from these upwind areas 

is an important contributor to ozone air quality in the Antelope Valley. In future years, 

emissions controls implemented in the upwind basins should benefit ozone air quality in 

the Antelope Valley. 

Figure 2: Hourly Average Ozone Concentrations on the Top Ten 1-Hour Ozone 

Days during 2006 at Lancaster 

 

5 Air Resources Board, 1990: Assessment and Mitigation of the Impacts of Transported Pollutants on 

Ozone Concentrations within California. ARB Staff Report prepared by the Technical Support Division 

and Office of Air Quality Planning and Liaison, June 1990.
AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

E-7

 

Hourly Average Ozone on the Top Ten 1-Hour Ozone Days During 2006

Lancaster-43301 Division Street

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0 1 2 34567 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23

Start Hour (PST)

Ozone Concentration (ppm)

Figure 3: Federal 8-Hour Ozone Design Values for Lancaster, Santa Clarita, and 

Edison 1995 to 2006 

 

Lancaster, Santa Clarita, & Edison Federal 8-Hr Ozone Design Values

0.00

0.02

0.04

0.06

0.08

0.10

0.12

0.14

0.16

0.18

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

Ozone (ppm)

Santa Clarita* Edison Lancaster**

* Santa Clarita site moved from the Fire Station to Placerita Canyon on 05/17/01. The 2001 and 2002 DVs reflect combined data.

** Lancaster site moved from W Pondera St. to Division St. on 11/01/01. The 2001 and 2002 DVs reflect combined data.

** 
E-8 AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

Ozone Air Quality Trends

The following discussion is based on ozone air quality data collected at sites in the 

Antelope Valley from 1995 through the present. During this time period, ozone 

concentrations were monitored at two locations in the Lancaster area. The 

Lancaster-West Pondera Street site was operating in 1995 and continued operating 

through the 2001 ozone season. At the beginning of November 2001, 

the site was relocated to Lancaster-Division Street, where it continues operating today. 

Because the site was relocated after the 2001 ozone season, data in the following 

graphs generally reflect the West Pondera Street site from 1995 through 2001 and the 

Division Street site from 2002 through the present. The 

exceptions to this are the design values for 2002 and 2003. Since the design value is 

based on data for a 3-year period, the design values for these years use a combination 

of data from both sites. It should be noted that when the site was relocated to Division 

Street, concentrations appeared to be somewhat higher. This has an impact on some 

of the trend lines – in particular, those based on only one or just a few values each year 

(for example, maximum concentration and number of exceedance days). However, 

because there is no overlap in the monitoring records for the two sites, an evaluation of 

the differences in concentrations at the two sites is not possible. In addition to the 

Lancaster sites, a site operated in Palmdale during 1995 only. Because the Palmdale 

data are so limited, they are not included in the following discussion.

Ozone trend indicators for Lancaster from 1995 to 2006 are shown in Figure 4. As 

shown, all indicators have decreased since 1995, indicating overall improvements in the 

various measures of ozone air quality. Similar to many other areas of the State, the 

largest drop is seen in the number of exceedance days. Although the trend is quite 

variable over the years, the overall decrease is 55 percent (from 35 days in 1995 to 16 

days in 2006). Data show a slightly lower value for 2007 – 14 exceedance days during 

the year. 

While the improvement in exceedance days is substantial, the improvement in the other 

indicators is more modest. Overall, the design value and mean of the Top 30 daily 

maximum concentrations decreased 10 percent between 1995 and 2006, while the 

maximum concentration decreased a little more than 5 percent. Similar to exceedance 

days, all three of these indicators had slightly lower values 

for 2007 than for 2006 (maximum concentration = 0.101 ppm in 2007 vs. 0.106 ppm in 

2006; design value = 0.095 ppm in 2007 vs. 0.096 ppm in 2006; mean Top 30 = 

0.086 ppm in 2007 vs. 0.087 ppm in 2006). Currently, the design value for Antelope 

Valley is still close to 15 percent above the federal standard, but this compares with a 

design value nearly 30 percent above the standard in 1995. Thus, since 1995, the area 

has made 50 percent of the progress needed to attain the standard. 

It is important to note that the trend lines for all four ozone indicators shown in Figure 4 

increased in 2002, when compared with 2001. As mentioned 
AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

E-9

Figure 4: Ozone Indicators for the Antelope Valley Planning Area 1995 to 2006 

 

Antelope Valley Planning Area Federal Ozone Statistics

0.00

0.03

0.06

0.09

0.12

0.15

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

Ozone (ppm)

0

20

40

60

80

100

Number of Days

Maximum Concentration Design Value* Mean Top 30 Exceedance Days

* Lancaster site moved from W Pondera St. to Division St. on 11/01/01. The 2001 and 2002 DVs reflect combined data.

previously, this is the same year the Lancaster site was relocated from West Pondera 

Street to Division Street, where concentrations appeared to be higher. Even so, the 

trend lines still show decreases from 2002 to the present. If the site had not been 

relocated, the overall decrease in the trend lines from 1995 to the present may have 

been greater. 

 

Looking at the more recent years, the trend in the maximum concentration shows a 

slight overall decrease when comparing 2002 to 2006, but shows an increase during the 

last three years. Because the maximum concentration is based on only one value each 

year and can be highly influenced by meteorology, it is not a good indicator of progress, 

nor is it used to measure compliance with the standard. The recent upward trend in the 

annual maximum concentration contrasts with small, but fairly consistent decreases in 

the other three indicators. When looking at the distribution of daily maximum 

concentrations that are below the annual maximum (i.e., the second through thirtieth 

daily maximum concentrations), it is apparent that although the annual maximum 

changed little, the second through thirtieth daily maximum concentrations have 

decreased over the years. This explains why the other indicators, design value, mean 

Top 30, and exceedance days, have all decreased, even though the annual maximum 

concentration has increased. 

Spatial Ozone Trends

Another way to look at the improvement in air quality is to map the change in the 

number of exceedance days. The maps in Figure 5 are based on monitoring data and 

show the reduction in the number of days exceeding the federal 8-hour standard over 

the last decade (1995 to 2005). This approach provides an estimate of the change in 
E-10 AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

the spatial extent of the ozone problem. Ten years ago (bottom 1995 map, based on 

1993 to 1995 means), about half of the Antelope Valley experienced 51 to 100 

exceedance days per year, while the other half 

experienced 21 to 50 days per year. Today (top 2005 map, based on 2003 to 2005 

means), nearly all of the Antelope Valley falls in the 21 to 50 days per year category, 

with a small portion having 11 to 20 days per year. 

 

The exceedance day maps clearly illustrate the influence of transport, particularly 

transport from the South Coast, on ozone air quality in both the Antelope Valley and 

southwest San Bernardino County areas. The highest count of exceedance 

Figure 5: Antelope Valley Change in Federal 8-Hour Exceedance Days 

1995 to 2005 

 
AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

E-11

days is found in the southern portion of these areas, adjacent to the South Coast Air 

Basin. Because of these transport impacts, emissions controls in the South Coast will 

be critical to attainment in the Mojave Desert Ozone Nonattainment Area. While areas 

closer to the South Coast still have the highest ozone concentrations, air quality in these 

areas has improved over time, and will continue to improve with the implementation of 

the South Coast and statewide emissions control strategies. 

Additional Air Quality Analyses

ARB staff conducted additional air quality analyses and also reviewed photochemical 

modeling for the Mojave Desert Ozone Nonattainment Area to assess whether the rate 

of progress historically, as well as the more modest progress in recent years, supports a 

2021 attainment date. 

 

Mean of the Top 30 Analysis 

The mean of the Top 30 represents the mean or average of the 30 highest daily 

maximum 8-hour ozone concentrations measured at a site during each year. Changes 

in this indicator over time reflect the change in the average ozone concentration on the 

30 worst days. Because this indicator is based on a relatively large number of 

observations, it is more robust than other indicators, such as maximum concentration. 

Although the mean of the Top 30 is not directly related to the federal standard, it does 

provide a stable indicator that is not highly influenced by year-to-year changes in 

meteorology. 

Figure 6 shows the trend in the mean of the Top 30 8-hour ozone concentrations for 

Antelope Valley. Since 1995, the mean of the Top 30 has declined 10 percent, from a 

concentration of 0.096 ppm in 1995 to 0.087 ppm in 2006. While there was a fairly 

substantial downward trend in the late 1990s, the trend line has been relatively flat since 

2000. 

As a way of gaining further insight into how the mean of the Top 30 has changed over 

time, ARB staff evaluated the rate of change, relative to the start year (1995). For this 

evaluation, 3-year averages of the annual mean Top 30 concentrations were normalized 

to the start year by calculating the ratio of the averaged Top 30 concentration for each 

year to the 1995 averaged Top 30 concentration. The normalized rate of progress 

values are plotted in Figure 7. 

Overall, Lancaster has shown some progress towards lower mean Top 30 

concentrations. There is a distinct change in the rate of progress from 2001 to 2002, 

which is the same time the Lancaster site was relocated. Since then, there 

has been progress, but the overall rate has been slight. Given the shape of the 

trend line since the site was relocated, it appears the downward trend will continue. 

However, given the slow rate of progress, the magnitude of emissions 
E-12 AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

reductions needed for attainment in the South Coast and San Joaquin Valley, and the 

timeframe for reducing these upwind emissions, it is unlikely that Antelope Valley will 

attain by 2010, its current deadline as a Moderate nonattainment area. 

Figure 6: Mean of the Top 30 8-Hour Ozone Concentrations for Antelope Valley 

 

Antelope Valley - Lancaster Site

Mean of Top 30 Ozone Concentrations

0.00

0.02

0.04

0.06

0.08

0.10

0.12

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

Concentration (ppm)

 

Figure 7: Mean of Top 30 8-Hour Ozone Concentrations at Lancaster 

Normalized to 1995 Start Year 

 

Antelope Valley - Lancaster Site

Normalized 3-Year Average Rate of Change of Mean Top 30 Ozone Concentrations

0.00

0.20

0.40

0.60

0.80

1.00

1.20

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

Ratio of Concentrations

Modeling Evaluations and Regression Analyses 
AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

E-13

As part of the photochemical modeling analyses, South Coast District staff evaluated 

the impacts of transport on attainment in the Mojave Desert Ozone Nonattainment Area. 

Using a gridded domain, South Coast District staff modeled several emissions reduction 

scenarios using two different 2005 modeling episodes. The scenarios included 

(1) removing emissions from the Mojave Desert Ozone Nonattainment Area; 

(2) removing emissions from Ventura and Santa Barbara counties; and (3) removing 

emissions from the South Coast. The results demonstrated that emissions from within 

the Mojave Desert Ozone Nonattainment Area were not sufficient to generate federal 

8-hour ozone exceedances and that emissions from the South Coast have an 

overwhelming impact. Therefore, emissions reductions in the upwind area are critical to 

attainment. 

As additional analyses, ARB staff completed regression analyses of design values for 

the South Coast versus Antelope Valley, as well as the San Joaquin Valley versus

Antelope Valley. Although there are a number of uncertainties associated with these 

analyses, the results suggest that the design value for Lancaster, in the Antelope 

Valley, will reach the level of attainment before either the South Coast or San Joaquin 

Valley, both of which have a 2024 attainment date. This lends further support to 

reclassifying, and therefore extending the attainment date for the Mojave Desert 

Nonattainment Area. 

Emissions Trends

In 2006, ROG emissions in the Antelope Valley were dominated by light duty passenger 

vehicles, petroleum marketing, degreasing, and consumer products. The main 

contributors of NOx emissions were off-road equipment, heavy duty diesel trucks, trains, 

and light duty passenger vehicles. Statewide and local emissions control measures 

have significantly reduced the amounts of both ROG and NOx emitted by various 

sources throughout California. However, emissions in Antelope Valley are 

overshadowed by emissions from the South Coast and San Joaquin Valley. Figure 8 

shows the estimated trend in the Antelope Valley ozone precursor emissions from 1995 

to 2006. The totals reflect estimates for the summer season in tons per day and include 

natural biogenic emissions. 

ROG emissions for the Antelope Valley show a relatively steady decline over the entire 

period, with an overall decrease of 20 percent. In contrast, NOx emissions decreased 

less than 5 percent, overall. But again, the amounts of emissions generated in the 

Antelope Valley are dwarfed by those in the upwind areas. During 2006, South Coast 

ROG emissions and NOx emissions were each about 30 times greater than those for 

the Antelope Valley, while San Joaquin Valley ROG and NOx emissions were each 

about 20 times greater. Furthermore, as discussed previously, emissions and pollutants 

from the South Coast and San Joaquin Valley can have an overwhelming impact on 

ozone air quality in the Antelope Valley via transport. 
E-14 AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

Figure 8: Antelope Valley Estimated ROG and NOx Emissions 1995 to 2006 

 

 

Antelope Valley Planning Area ROG & NOx Emissions

Summer SIP Inventory with Biogenics - Ver 1.06

0

5

10

15

20

25

30

35

40

45

1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006

Year

Emissions (tons/day)

ROG NOx

Photochemical Modeling Results

The U.S. EPA (2005) provided criteria for calculating future year 8-hour ozone design 

values using air quality simulation results. Among these criteria were recommendations 

for air quality model performance, observed and simulated ozone concentration 

thresholds, and the number of simulated days used to calculate the relative response 

factor (RRF) used to scale reference year design values for future years. To meet 

these criteria, the South Coast District staff evaluated results from the simulation of six 

high ozone episode periods during 2004 and 2005. 

Of the six episodes, the simulation results for the July 15 through 19, 2005 and the 

August 3 through 9, 2005 episode periods showed high concentrations and acceptable 

air quality model performance for ozone monitoring sites in the Mojave Desert Ozone 

Nonattainment Area. Therefore, subsequent analysis focused on these two periods. To 

evaluate future year ozone design values, the South Coast District staff simulated these 

episodes using emissions inventories developed for the years 2002 (the reference year 

for design values), 2005 (to evaluate ozone model performance), 2012, 2017 (for an 

attainment year of 2018), and 2020 (for an attainment year of 2021). Emissions totals 

were based on projections from the South Coast District’s 2007 Air Quality Management 

Plan. 

Based on the results, Phelan and Hesperia in the San Bernardino portion of the 

Nonattainment Area have the highest design values in 2017, but do not meet the federal 

8-hour standard by then. The 2017 design value for Lancaster is predicted at 0.08 ppm, 

which is below the level of the standard. However, because all sites in the 

Nonattainment Area must have design values below the standard to be in attainment, a 

2018 attainment date is not appropriate. In contrast, modeling predicted a design value 
AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

E-15

at Phelan of 0.080 ppm by the end of 2020, which does show attainment and is 

consistent with a June 15, 2021 attainment deadline. The predicted 2020 design value 

for Lancaster is 0.074 ppm. Based on the modeling analysis, all sites in the Mojave 

Desert Nonattainment Area show attainment by the end of 2020, as required for a 

Severe-17 nonattainment area and consistent with a June 15, 2021 attainment 

deadline. 

Summary

The Weight of Evidence package comprises a set of analyses that provide support for 

the attainment demonstration. Currently, the Mojave Desert Ozone Nonattainment Area 

is classified as Moderate with respect to the federal 8-hour ozone standard, with 

attainment required by 2010. Because of the transport impact of emissions and 

pollutants from the South Coast and San Joaquin Valley, as well as the expected timing 

of emissions reductions in these upwind areas, the Antelope Valley Air Quality 

Management District and the Mojave Desert Air Quality Management District are both 

requesting reclassification of their planning areas as Severe-17, with an attainment date 

of June 15, 2021. Based on the air quality and emissions analyses completed for the 

WOE assessment, attainment in the Antelope Valley portion of the planning area can be 

projected by 2021, based on the following factors: 

• Since 1995, there has been a 55 percent decrease in exceedance 

days, a 10 percent decrease in design value and mean Top 30, and a 

5 percent decrease in maximum concentration. Progress has slowed 

over the last five to six years. However, in spite of this, the ozone 

indicators, taken together, continue to show improvement, albeit at a 

slower rate over the last several years. 

• The design value for Antelope Valley is now less than 15 percent 

above the level of the federal standard. Furthermore, since 1995, the 

area has achieved 50 percent of the progress needed to reach 

attainment. 
E-16 AVAQMD Federal 8-hour Ozone Attainment Plan 

May 20, 2008 

• Transport and air quality analyses support a link between the South 

Coast and Antelope Valley, as well as the San Joaquin Valley and 

Antelope Valley, with respect to ozone air quality. ROG and NOx 

emissions in the upwind areas are 20 to 30 times the level of those in 

the Antelope Valley. Furthermore, the transport impact from the 

upwind areas is overwhelming on some days. Modeling analyses 

show that attainment in the Antelope Valley will be dependent on 

emissions reductions in the upwind areas. 

• The South Coast, San Joaquin Valley, and statewide emissions control 

strategies are expected to result in massive emissions reductions over 

the next 15 years, with both of these areas expecting attainment by 

2024. These emissions reductions will also facilitate attainment in 

downwind areas such as the Antelope Valley. Because ozone levels in 

the Antelope Valley are not as high as those in either the South Coast 

or San Joaquin Valley, the emissions reductions needed for attainment 

in the Antelope Valley are not as high. Therefore, attainment will occur 

earlier than 2024. 

• Although there is a great deal of uncertainty in the regression analyses 

completed for the Antelope Valley, they do suggest that Antelope 

Valley will reach attainment before either the South Coast or 

San Joaquin Valley air basins. 

• Photochemical modeling shows the Antelope Valley will not attain by 

2010, but will have a design value that meets the federal standard by 

the end of 2017. However, because the Antelope Valley is considered 

with a portion of San Bernardino County as a single nonattainment 

area, it cannot be designated as attainment until all sites in the region 

meet the standard. Photochemical modeling results show that the 

entire Mojave Desert Ozone Nonattainment Area will attain by the end 

of 2020, with all sites having a design value of 0.082 ppm or less. At 

this time, the design value for Lancaster will be 0.074 ppm, which is 

well below the level of the federal standard. 

Taken together, the results from all of these analyses indicate the Antelope Valley 

Planning Area will not attain the federal 8-hour ozone standard by 2010, the area’s a 

current deadline as a Moderate ozone nonattainment area. However, given the recent 

trends, the transport impact from the South Coast and San Joaquin Valley, and the 

expected level and timing of emissions reductions in these upwind areas, the entire 

Mojave Desert Ozone Nonattainment Area can expect to reach attainment by the end of 

2020, consistent with the June 15, 2021 attainment deadline for Severe-17 

nonattainment areas.