SACRAMENTO REGIONAL

8-HOUR OZONE ATTAINMENT AND

REASONABLE FURTHER PROGRESS PLAN

(2013 SIP REVISIONS)

September 26, 2013
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

El Dorado County Air Quality Management District

Dave Johnston, Air Pollution Control Officer

2850 Fairlane Court, Bldg. C

Placerville, CA 95667-4100

(530) 621-7501

http://edcgov.us/AirQualityManagement/

Feather River Air Quality Management District

Christopher Brown, Air Pollution Control Officer

1007 Live Oak Blvd Suite B-3 Yuba City, CA 95991

(530) 634-7660

http://www.fraqmd.org

Placer County Air Pollution Control District

Tom Christofk, Air Pollution Control Officer

110 Maple Street

Auburn, CA 95603

(530) 745-2330

http://www.placer.ca.gov/Departments/Air.aspx

Sacramento Metropolitan Air Quality Management District

Larry Greene, Air Pollution Control Officer

777 12th Street, Third Floor

Sacramento, CA 95814-1908

(916) 874-4800

http://www.airquality.org

Yolo-Solano Air Quality Management District

Mat Ehrhardt, Air Pollution Control Officer

1947 Galileo Court, Suite 103

Davis, CA 95618

(530) 757-3650

http://www.ysaqmd.org
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Title Page

Page i

SACRAMENTO REGIONAL

8-HOUR OZONE ATTAINMENT AND

REASONABLE FURTHER PROGRESS PLAN

(2013 SIP REVISIONS)

This Plan demonstrates how existing and new control strategies 

will provide the necessary future emission reductions to meet 

the federal Clean Air Act requirements for reasonable further 

progress and attainment of the 1997 8-hour ozone NAAQS for 

the Sacramento region. In addition, this Plan includes an 

updated emission inventory, sets new motor vehicle emission

budgets for transportation and general conformity purposes, 

provides photochemical modeling results, and documents the 

implementation of reasonably available control measures.

September 26, 2013
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Acknowledgements

Page ii

ACKNOWLEDGEMENTS

This report was prepared by Sacramento Metropolitan Air Quality Management District 

staff from the Program Coordination Division and the Mobile Source and Land Use

Division as a joint project with the El Dorado County Air Quality Management District, 

Feather River Air Quality Management District, Placer County Air Pollution Control 

District, Yolo-Solano Air Quality Management District, and Sacramento Area Council of 

Governments.

Project Oversight

Brigette Tollstrup, Charles Anderson

Lead Authors

Bruce Katayama, Greg Tholen, Steven Lau, Janice Lam

Subject (Authors or Contributors)

Emissions Inventory: Hao Quinn, Jimmy Cheng, Karen Taylor

Mobile Source and Land Use Control Measures: Tim Taylor

Transportation Control Measures: Jason Crow, SACOG

Stationary Source Control Measure Authors

Oversight and Sacramento AQMD: Aleta Kennard

Yolo-Solano AQMD: Matt Jones

Placer County APCD: Yu-Shuo Chang

El Dorado County AQMD: Carolyn Craig, Adam Baughman

Feather River AQMD: Sondra Spaethe

We would like to thank staff from the California Air Resources Board for their major 

contributions in the development of the updated motor vehicle emissions budgets, 

photochemical modeling, weight-of-evidence analyses, and reasonable further progress 

evaluation. Various consultants and California Air Resources Board staff also provided 

information on local, state, and federal control measures in conjunction with the 

attainment demonstration modeling assessment. In addition, we would like to 

acknowledge all of the governmental agencies, organizations, and consultants involved 

in the Central California Ozone Study (CCOS) which provided the basis for the 

photochemical modeling.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Table of Contents

Page iii

TABLE OF CONTENTS

LIST OF TABLES..........................................................................................................viii

LIST OF FIGURES.......................................................................................................... x

LIST OF ABBREVIATIONS AND ACRONYMS..............................................................xii

1 EXECUTIVE SUMMARY...................................................................................1-1

1.1 Background Information on Ozone 1-1

1.2 Overview of Federal 8-Hour Ozone Standard 1-1

1.3 8-Hour Ozone Trends in the Sacramento Region 1-2

1.4 VOC and NOX Emissions Inventory 1-3

1.5 Air Quality Modeling Analysis 1-5

1.6 Proposed Regional and Local Control Measures 1-5

1.7 Attainment Demonstration 1-9

1.8 Transport Analysis 1-10

1.9 Weight-of-Evidence Determination 1-11

1.10 Transportation Conformity and Emission Budgets 1-12

1.11 General Conformity 1-13

1.12 Reasonable Further Progress Demonstration 1-14

1.13 Conclusions 1-15

2 BACKGROUND INFORMATION and PLAN DEVELOPMENT OVERVIEW .....2-1

2.1 Ozone Health Effects 2-1

2.2 Ozone Formation and Precursor Pollutants 2-1

2.3 Clean Air Act and Prior Federal 1-Hour Ozone Standard 2-2

2.4 1994 Sacramento Area Regional Ozone Attainment Plan 2-2

2.5 Federal 8-Hour Ozone Standard 2-3

2.6 Development of the Sacramento Regional 8-Hour Ozone Attainment and 

Reasonable Further Progress Plan 2-5

2.7 Public Input and Review Process 2-6

2.8 Contents of 8-Hour Ozone Plan 2-6

3 FEDERAL CLEAN AIR ACT REQUIREMENTS ................................................3-1

3.1 Purpose of a Federal Ozone Attainment Plan 3-1

3.2 Federal Clean Air Act Requirements 3-1
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3.3 New Source Review (NSR) and Other Permitting Requirements 3-2

3.4 Reasonably Available Control Technology (RACT) Requirements 3-2

3.5 Reasonably Available Control Measures (RACM) Requirements 3-3

3.6 Vehicle Miles Travelled (VMT) Offset Requirement 3-3

3.7 Sacramento Nonattainment Area Designation 3-4

3.8 Nonattainment Classification and Attainment Deadline 3-4

3.9 Reasonable Further Progress Plan 3-5

4 8-HOUR OZONE AIR QUALITY TRENDS........................................................4-1

4.1 Introduction to Air Quality Trends 4-1

4.2 Ozone Monitoring Sites 4-1

4.3 Annual Number of Exceedance Days 4-1

4.4 Trend in Exceedance Days 4-1

4.5 Ozone Design Values 4-2

4.6 Trend in Ozone Design Value 4-2

5 EMISSIONS INVENTORY.................................................................................5-1

5.1 Introduction to Emissions Inventory 5-1

5.2 Emission Inventory Requirements 5-1

5.3 Emission Inventory Source Categories 5-2

5.4 Base Year Emissions Inventory 5-5

5.5 Emission Inventory Forecasts 5-14

5.6 Emission Reduction Credits Added to Emission Inventory Forecasts 5-17

5.7 Emissions Inventory Documentation 5-18

6 AIR QUALITY MODELING ANALYSIS..............................................................6-1

6.1 Introduction to Air Quality Modeling 6-1

6.2 Air Quality Modeling Methodology and Applications 6-1

6.3 Air Quality Modeling Analysis Requirements 6-1

6.4 Central California Ozone Study 6-2

6.5 Description of Air Quality Model and Modeling Inputs 6-3

6.6 Selection and Characterization of Modeling Episodes 6-5

6.7 Base Case Model Performance Evaluation 6-6

6.8 Baseline and Future Year Model Runs for Each Episode 6-6

6.9 Emission Reduction Credits Added to Future Year Model Runs 6-7
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6.10 Forecasted Ozone Design Values 6-7

6.11 Analysis of VOC and NOX Emission Reduction Strategies 6-10

6.12 Air Quality Modeling Uncertainties 6-11

7 PROPOSED CONTROL MEASURES...............................................................7-1

7.1 Introduction to Control Measures 7-1

7.2 Reductions from Existing Controls 7-1

7.3 Reductions from New State and Federal Control Measures 7-3

7.4 Consideration and Selection of New Regional and Local Control Measures7-12

7.5 SIP Control Measure Commitments 7-12

7.6 SIP Emission Reduction Tracking 7-13

7.7 Non-regulatory Control Measures 7-13

7.8 Mobile Source Incentive Measures 7-14

7.9 “Spare The Air Program” 7-16

7.10 SACOG Transportation Control Measures 7-17

7.11 New and Continuing TCM Projects 7-18

7.12 Research and Policy Development TCMs 7-23

7.13 Urban Forest Air Quality Development Program 7-24

7.14 Regulatory Control Measures 7-26

7.15 Stationary and Area-wide Source Control Measures 7-26

7.16 VOC Emission Control Measures 7-27

7.17 NOX Emission Control Measures 7-30

7.18 Summary of Regional and Local Proposed Emission Reductions 7-31

7.19 Further Study Measures 7-33

7.20 Contingency Measures 7-34

8 ATTAINMENT DEMONSTRATION ...................................................................8-1

8.1 Introduction to Attainment Demonstration 8-1

8.2 Attainment Demonstration Requirements 8-1

8.3 Attainment Demonstration Evaluation 8-1

8.4 Attainment Demonstration Conclusions 8-3

8.5 Summary of Attainment Demonstration 8-5

8.6 Attainment Demonstration Contingency Measures Requirement 8-6

9 TRANSPORT ANALYSIS..................................................................................9-1
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9.1 Introduction to Pollutant Transport 9-1

9.2 Interbasin Transport Issues 9-1

9.3 EPA Rules and Regulations on Intrastate Transport 9-2

9.4 Attainment Assumptions of Domain-wide Reductions 9-2

10 WEIGHT-OF-EVIDENCE DETERMINATION..................................................10-1

10.1 Introduction to Weight-of-Evidence 10-1

10.2 Weight-of-Evidence Requirements 10-1

10.3 Methodology for Applying Weight-of-Evidence Analyses 10-2

10.4 Summary of CARB Weight-of-Evidence Analyses 10-2

11 TRANSPORTATION CONFORMITY AND EMISSION BUDGETS .................11-1

11.1 Introduction to Transportation Conformity 11-1

11.2 Transportation Conformity Requirements 11-1

11.3 Purpose of the Motor Vehicle Emissions Budget 11-1

11.4 Latest Planning Assumptions 11-2

11.5 SACOG’s Blueprint and MTP/SCS 2035 11-2

11.6 Proposed New Motor Vehicle Emissions Budgets 11-4

11.7 Motor Vehicle Emissions Budget Approval Process 11-5

11.8 Vehicle Miles Traveled Offset (VMT Offset) 11-6

12 GENERAL CONFORMITY ..............................................................................12-1

12.1 Introduction to General Conformity 12-1

12.2 General Conformity Requirements 12-1

12.3 Types of Federal Actions Subject to General Conformity Requirements 12-2

12.4 Emissions Criteria for Demonstrating General Conformity 12-2

12.5 Airports Emissions Inventory 12-3

13 REASONABLE FURTHER PROGRESS DEMONSTRATIONS ......................13-1

13.1 Introduction to Reasonable Further Progress 13-1

13.2 Reasonable Further Progress Requirements 13-1

13.3 Contingency Measures Requirement 13-1

13.4 Methodology for Reasonable Further Progress Demonstrations 13-2

13.5 Calculations of Reasonable Further Progress Demonstrations 13-4

14 SUMMARY AND CONCLUSIONS ..................................................................14-1

14.1 8-Hour Ozone Nonattainment Designation for Sacramento Region 14-1
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and Reasonable Further Progress Plan September 26, 2013

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14.2 “Severe” 8-Hour Ozone Classification with 2019 Attainment Deadline 14-1

14.3 Trend in Ozone Air Quality Shows Improvement 14-1

14.4 VOC and NOX Emissions Inventory Forecasted to Decline 14-2

14.5 Air Quality Modeling Analysis Indicates Additional Emission Reductions Are 

Needed for Attainment 14-3

14.6 Proposed Regional and Local Control Measures 14-4

14.7 2018 Attainment Demonstration 14-7

14.8 Pollutant Transport from Upwind Bay Area Region 14-8

14.9 Weight-of-Evidence Determination 14-9

14.10 Transportation Conformity and Motor Vehicle Emissions Budgets 14-10

14.11 Updated Emissions Inventory for General Conformity 14-11

14.12 Reasonable Further Progress Demonstration Achieved 14-12

14.13 Future Ozone Planning Efforts 14-12

APPENDICES

A. EMISSIONS INVENTORY

B. PHOTOCHEMICAL MODELING

C. PROPOSED CONTROL MEASURES

D. TRANSPORTATION CONTROL MEASURES

E. WEIGHT-OF-EVIDENCE ANALYSES

F. MOTOR VEHICLE EMISSIONS BUDGETS

G. REASONABLE FURTHER PROGRESS DEMONSTRATIONS

H. REASONABLY AVAILABLE CONTROL MEASURES (RACM) ANALYSIS

I. FEDERAL CLEAN AIR ACT REQUIREMENTS
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List of Tables

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LIST OF TABLES

Table 1-1 Emissions Inventory of Volatile Organic Compounds - Sacramento 

Nonattainment Area ..................................................................................1-4

Table 1-2 Emissions Inventory of Nitrogen Oxides - Sacramento Nonattainment Area

..................................................................................................................1-5

Table 1-3 Summary of New Regional and Local Proposed Control Measures –

Sacramento Nonattainment Area ..............................................................1-7

Table 1-4 Summary of SACOG Transportation Control Measures ............................1-8

Table 1-5 Summary of Attainment Demonstration for 8-Hour Ozone NAAQS 2018 

“Severe” Classification Scenario .............................................................1-10

Table 1-6 Proposed New Motor Vehicle Emissions Budgets – Sacramento 

Nonattainment Area ................................................................................1-12

Table 4-1 8-Hour Ozone Exceedance Days – Sacramento Nonattainment Area –

Ozone Monitoring Sites .............................................................................4-4

Table 4-2 8-Hour Ozone Design Values – Sacramento Nonattainment Area –Ozone 

Monitoring Sites.........................................................................................4-7

Table 5-1 Biogenic Emissions ...................................................................................5-5

Table 5-2 Emissions of VOC (tons per day) – Sacramento Nonattainment Area ......5-7

Table 5-3 Emissions of NOX (tons per day) – Sacramento Nonattainment Area .......5-8

Table 5-4 VOC Emission Reduction Credits Added to the Emission Inventory 

Forecasts – Sacramento Nonattainment Area........................................5-19

Table 5-5 NOX Emission Reduction Credits Added to the Emission Inventory 

Forecasts – Sacramento Nonattainment Area.........................................5-19

Table 6-1 Forecasted 8-Hour Ozone Design Values – 2018 Attainment Analysis Year 

for Severe Classification............................................................................6-9

Table 7-1 State Measures Adopted Since 2007 ........................................................7-3

Table 7-2 Analysis of ARB’s Implemented Regulations using Calendar Year 2018 NOX

Summer Season Emissions (tpd)..............................................................7-4

Table 7-2A Phase-in of truck engine standards ...........................................................7-6

Table 7-2B Phase-in of off-road engine standards 7-7
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Page ix

Table 7-3 Summary of SACOG Transportation Control Measures – New and 

Continuing Projects and Funding Programs ............................................7-22

Table 7-4 Summary of SACOG Transportation Control Measures – Research and 

Policy Development Studies....................................................................7-23

Table 7-5 Summary of New Regional and Local Proposed Control Measures –

Sacramento Nonattainment Area ............................................................7-32

Table 8-1 Summary of Attainment Demonstration for 8-Hour Ozone NAAQS – 2018 

“Severe” Classification Scenario ...............................................................8-5

Table 8-2 Attainment Contingency Measures Reductions – Sacramento 

Nonattainment Area ..................................................................................8-6

Table 11-1 Proposed New Motor Vehicle Emissions Budgets – Sacramento 

Nonattainment Area ................................................................................11-4

Table 12-1 Airport (Aircraft Operations + Ground Support Equipment) Emissions for the

Sacramento Nonattainment Area ............................................................12-4

Table 13-1 Calculation of Reasonable Further Progress Demonstrations – Sacramento 

Nonattainment Area ................................................................................13-5

Table 14-1 Summary of New Regional and Local Proposed Control Measures –

Sacramento Nonattainment Area ............................................................14-5

Table 14-2 Summary of SACOG Transportation Control Measures – New and 

Continuing Projects and Funding Programs ............................................14-6

Table 14-3 Summary of 2018 Attainment Demonstration for 1997 8-Hour Ozone

NAAQS....................................................................................................14-8

Table 14-4 Proposed New Motor Vehicle Emissions Budgets – Sacramento 

Nonattainment Area ..............................................................................14-10
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List of Figures

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LIST OF FIGURES

Figure 1-1 8-Hour Ozone Exceedance Days – Sacramento Nonattainment Area – Peak 

Monitoring Site ..........................................................................................1-3

Figure 1-2 8-Hour Ozone Design Values – Sacramento Nonattainment Area – Peak 

Monitoring Site ..........................................................................................1-3

Figure 1-3 Summary of Reasonable Further Progress Demonstrations – Sacramento 

Nonattainment Area ................................................................................1-15

Figure 3-1 Federal 8-Hour Ozone Sacramento Nonattainment Area..........................3-7

Figure 4-1 Sacramento Nonattainment Area Ozone Monitoring Stations ...................4-3

Figure 4-2 8-Hour Ozone Exceedance Days – Sacramento Nonattainment Area – Peak 

Monitoring Site ..........................................................................................4-5

Figure 4-3 8-Hour Ozone Exceedance Days Trend – Sacramento Nonattainment Area 

– Peak Monitoring Site .............................................................................4-6

Figure 4-4 8-Hour Ozone Design Values Trend – Sacramento Nonattainment Area 

– Peak Monitoring Site ..............................................................................4-8

Figure 5-1 2002 VOC Planning Inventory – Sacramento Nonattainment Region .....5-10

Figure 5-2 2002 NOX Planning Inventory – Sacramento Nonattainment Region ......5-10

Figure 5-3 Top Ten Categories for VOC Planning Emissions – Sacramento 

Nonattainment Region.............................................................................5-11

Figure 5-4 Top Ten Categories for NOX Planning Emissions – Sacramento 

Nonattainment Region.............................................................................5-12

Figure 5-5 VOC Emissions Contribution by Primary Agency Responsibility –

Sacramento Nonattainment Region ........................................................5-13

Figure 5-6 NOX Emissions Contribution by Primary Agency Responsibility –

Sacramento Nonattainment Region ........................................................5-13

Figure 5-7 Population Growth Forecast – Sacramento Nonattainment Area ............5-15

Figure 5-8 VOC Planning Inventory Forecasts – Sacramento Nonattainment Region.....

................................................................................................................5-16
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Figure 5-9 NOX Planning Inventory Forecasts – Sacramento Nonattainment Region .....

................................................................................................................5-16

Figure 6-1 Photochemical Modeling Domain – Central California Ozone Study.........6-5

Figure 7-1 2008 Benefits From District VOC Rules Since 1975 – 60 TPD – Sacramento 

Nonattainment Area ..................................................................................7-2

Figure 7-2 2008 Benefits From District NOX Rules Since 1975 – 20 TPD – Sacramento 

Nonattainment Area ..................................................................................7-2

Figure 8-1 Attainment Demonstration Analysis – Predicted 2018 Regional Peak Ozone 

Design Value at Cool – Sacramento Nonattainment Area.........................8-4

Figure 13-1Summary of Reasonable Further Progress Demonstrations –Sacramento 

Nonattainment Area ................................................................................13-6

Figure 14-1VOC and NOX Emission Forecasts – Sacramento Nonattainment Area..14-3

Figure 14-2Summary of Reasonable Further Progress Demonstrations –Sacramento 

Nonattainment Area ..............................................................................14-12
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List of Abbreviations and Acronyms

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LIST OF ABBREVIATIONS AND ACRONYMS

94SIP - 1994 Sacramento Area Regional Ozone Attainment Plan

ABAG - Association of Bay Area Governments

APCD - Air Pollution Control District

AQMD - Air Quality Management District

ARB - California Air Resources Board

BAR - Bureau of Automotive Repair

BTU - British thermal unit

BVOC - biogenic volatile organic compounds

CAA - Clean Air Act

CAMx - Comprehensive Air Quality Model with extension

CARB - California Air Resources Board

CCOS - Central California Ozone Study

CEFS - California Emissions Forecasting System

CEQA - California Environmental Quality Act

CFR - Code of Federal Regulations

CI - compression ignition

CMAQ - Congestion Mitigation and Air Quality Improvement Program

CMR - Construction Mitigation Rule

CTG - Control Techniques Guidelines

DOF - Department of Finance

DOT - U.S. Department of Transportation

DRI - Desert Research Institute

DTIM - Direct Travel Impact Model

EDCAQMD - El Dorado County Air Quality Management District

EIC - emission inventory category code

EMFAC - California’s on-road motor vehicle emission factor model

EMS - Emissions Modeling System

EPA - U.S. Environmental Protection Agency
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List of Abbreviations and Acronyms

Page xiii

ERCs - emission reduction credits

FDDA - four dimensional data analysis

FHWA - Federal Highway Administration of DOT

FMVCP - federal motor vehicle control program

FR - Federal Register

FRAQMD - Feather River Air Quality Management District

FTA - Federal Transit Administration of DOT

GVWR - gross vehicle weight rating

HDGT - heavy-duty gas trucks

HDV - heavy-duty vehicles

HHDDT - heavy heavy-duty diesel trucks

IC - internal combustion

ICC - Interagency Coordination Committee

I/M - motor vehicle inspection and maintenance

ISR - Indirect Source Rule

ITS - Intelligent Transportation Systems

LDV - light-duty vehicles

LHDT - light heavy-duty trucks

MC - Mountain Counties

MCR - mid-course review

MHR - Mather Airport

MM5 - Mesoscale Model version 5

MNB - mean normalized bias

MNGE - mean normalized gross error

MPO - Metropolitan Planning Organization

MTC - Metropolitan Transportation Commission (Bay Area)

MTIP - Metropolitan Transportation Improvement Program

MTP - Metropolitan Transportation Plan

MTP2035 - Metropolitan Transportation Plan for 2035

MVEB - motor vehicle emissions budget
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List of Abbreviations and Acronyms

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MVSTAFF - Motor Vehicle Stock, Travel and Fuel Forecast (Caltrans Report)

NAA - nonattainment area

NAAQS - national ambient air quality standard

NG - natural gas

NSR - new source review

NOX - nitrogen oxides

OAQPS - EPA Office of Air Quality Planning and Standards

OBD - onboard diagnostics

PCAPCD - Placer County Air Pollution Control District

ppb - parts per billion

ppm - parts per million

RACM - reasonably available control measure

RACT - reasonably available control technology

RFP - reasonable further progress

ROG - reactive organic gases

ROP - rate-of-progress

RRF - relative reduction factor

RVP - Reid vapor pressure

SACMET - SACOG’s previous regional transportation model

SACOG - Sacramento Area Council of Governments

SACSIM - SACOG’s new regional transportation model

SAPRC - Statewide Air Pollution Research Center

SECAT - Sacramento Emergency Clean Air and Transportation

SFNA - Sacramento Federal Nonattainment Area

SI - spark ignited

SIP - State Implementation Plan

SJVAPCD - San Joaquin Valley Air Pollution Control District

SMAQMD - Sacramento Metropolitan Air Quality Management District

SMF - Sacramento International Airport

SNA - Sacramento Nonattainment Area
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List of Abbreviations and Acronyms

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SOCMI - Synthetic Organic Chemical Manufacturing Industry

SRTS - Safe Route to Schools

STARNET - Sacramento Transportation Area Network

SV - Sacramento Valley

TCM - transportation control measure

TDM - Transportation Demand Management

TMA - Transportation Management Association

tpd - tons per day

UAM - Urban Airshed Model

ULEV - ultra-low emission vehicle

VMT - vehicle miles traveled

VOC - volatile organic compounds

YSAQMD - Yolo-Solano Air Quality Management District
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Executive Summary

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1 EXECUTIVE SUMMARY

1.1 Background Information on Ozone

Air pollution or “smog” is composed of many different gaseous and particulate 

pollutants, which can create a regional haze reducing atmospheric visibility. Groundlevel ozone, a colorless gas, is a major component of photochemical smog. Since 

ozone is formed especially in the presence of strong sunlight, ambient ozone 

concentrations are more problematic during May through October in the Sacramento 

region.

Ground-level ozone can have harmful health effects. Breathing air containing ozone can 

reduce lung function and increase respiratory symptoms, thereby aggravating asthma, 

bronchitis, or other respiratory conditions including chest pains and wheezing. Ozone 

exposure has been associated with increased susceptibility to respiratory infections, 

cardiac-related effects, medical visits, school absenteeism, and contributing to 

premature death, especially in people with heart and lung disease. Ozone can also 

cause damage to crops and natural vegetation by acting as a chemical oxidizing agent.

Ozone is formed as a result of photochemical reactions involving two types of precursor 

pollutants: volatile organic compounds (VOC) and nitrogen oxides (NOX). VOC and NOX

air pollutants are emitted by many types of sources, including on-road and off-road 

combustion engine vehicles, power plants, industrial facilities, gasoline stations, organic 

solvents, and consumer products. VOC pollutants are also known as reactive organic 

gases (ROG).

1.2 Overview of Federal 8-Hour Ozone Standard

The 1997 federal 8-hour ozone standard lowered the health-based limit for ambient 

ozone concentration from 0.12 parts per million of ozone averaged over one hour1to 

0.08 parts per million of ozone averaged over eight hours2. An area’s nonattainment

designation is based on whether the 8-hour ozone design value for any of the 

monitoring sites in the area exceeds the national ambient air quality standard (NAAQS).

The Sacramento region is designated a nonattainment area, and includes all of 

Sacramento and Yolo counties and portions of Placer, El Dorado, Solano, and Sutter 

counties.

Nonattainment areas are classified as marginal, moderate, serious, severe, or extreme 

areas depending on the magnitude of the highest 8-hour ozone design value for the 

monitoring sites in the nonattainment area. In 2004, the Sacramento region was

classified as a “serious” nonattainment area with an attainment deadline of June 15, 

 

1

The one-hour ozone standard violation criterion is defined as no more than 3 daily exceedances (>124 

ppb) over 3 years at a monitoring site.

2 Under the eight-hour ozone standard violation criterion, the annual 4th

-highest daily maximum 8-hour 

ozone concentration averaged over 3 years (i.e., ozone design value) may not exceed 84 ppb at a 

monitoring site.
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Executive Summary

Page 1-2

2013. This classification was based on the 8-hour ozone design value of 107 ppb at 

Cool, calculated from ozone concentrations monitored from 2001 to 2003.

However, since the Sacramento region needs to rely on the longer term emission 

reduction strategies from state and federal mobile source control programs, the 2013 

attainment date cannot be met. Consequently, on February 14, 2008, CARB, on behalf 

of the air districts in the Sacramento region, submitted a letter to EPA requesting a 

voluntary reclassification (bump-up) of the Sacramento Federal Nonattainment Area 

from a “serious” to a “severe” 8-hour ozone nonattainment area with an extended 

attainment deadline of June 15, 20193. EPA approved the reclassification request on 

May 5, 2010 (75 FR 24409).

This plan includes the information and analyses to fulfill the federal Clean Air Act 

requirements for demonstrating reasonable further progress and attainment of the 1997 

8-hour ozone NAAQS for the Sacramento region. In addition, this plan establishes an 

updated emissions inventory, provides photochemical modeling results, proposes the 

implementation of reasonably available control measures, and sets new motor vehicle 

emission budgets for transportation conformity purposes.

1.3 8-Hour Ozone Trends in the Sacramento Region

The progress toward attainment is measured by analyzing ambient air quality data 

collected at various monitoring sites over a period of many years (1990-2007). There 

are currently 16 ozone monitoring stations located throughout the Sacramento region

that are operated by either local air districts or the California Air Resources Board.

The annual number of 8-hour ozone exceedance days recorded at the peak monitoring 

sites fluctuates from year to year due to meteorological variability and changes in 

precursor emission patterns. The most frequent exceedances of the federal 8-hour 

ozone standard occur at the region’s eastern monitoring sites (Cool, Folsom, Placerville, 

and Auburn). The 18-year trend line indicates a decline in the overall average peak 

number of annual exceedance days, from about 33 down to 22 (see Figure 1-1).

 

3

In order to attain by June 15th, the prior year’s ozone season would need to be in attainment, making 

2018 to be the attainment demonstration analysis year.
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Executive Summary

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Figure 1-1

8-Hour Ozone Exceedance Days

Sacramento Nonattainment Area – Peak Monitoring Site

Federal 8-hr ozone standard = 84 ppb

This trend analysis uses the highest number of 8-hour ozone exceedance days recorded each year at the various monitoring 

sites, including the addition of the Cool station in 1996.

The peak 8-hour ozone design value concentration also varies from year to year and 

occurs at the eastern monitoring sites in the Sacramento region. The overall 18-year 

trend line shows a slight decline, from 108 ppb down to about 100 ppb (see Figure 1-2).

The design value has improved from being 24 ppb (or 28%) over the standard4down to 

about 16 ppb (or 19%).

Figure 1-2

8-Hour Ozone Design Values

Sacramento Nonattainment Area – Peak Monitoring Site

Federal 8-hr ozone standard = 84 ppb

This trend analysis uses the highest 8-hour ozone design values based on ozone concentrations recorded each year at the 

various monitoring sites, including the addition of the Cool station in 1996

1.4 VOC and NOX Emissions Inventory

Ozone is not directly emitted into the atmosphere, but is a pollutant produced by 

photochemical reactions in the air involving volatile organic compounds (VOC) and 

 

4

Federal 8-hour ozone standard = 84 ppb.

y = -0.6821x + 33.647

R

2

 = 0.14

0

5

10

15

20

25

30

35

40

45

50

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

Year

Days Exceeding

Federal 8-hr ozone standard = 84 ppb

y = -0.4438x + 107.99

R

2

 = 0.4238

84

88

92

96

100

104

108

112

116

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007

Year

Ozone Concentration (ppb)

Federal 8-hr ozone standard = 84 ppb
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Executive Summary

Page 1-4

nitrogen oxides (NOX). Therefore, planning efforts to evaluate and reduce ozone air 

pollution include identifying and quantifying the various processes and sources of VOC 

emissions (such as solvents, surface coatings, and motor vehicles) and NOX emissions 

(such as motor vehicles and other fuel combustion equipment).

EPA emission inventory guidance requires the planning emissions inventory to be 

based on estimates of actual emissions for an average summer weekday, typical of the 

ozone season (May – October). The anthropogenic emissions inventory is first divided 

into four broad source categories: stationary sources, area-wide sources, on-road motor 

vehicles, and other mobile sources. Each of these major categories is further defined 

into more descriptive equipment types and specific emission processes. The biogenic 

VOC emissions from vegetation for natural areas, crops, and urban landscapes are 

estimated separately from the anthropogenic inventory.

The 2002 base year anthropogenic planning inventory is estimated to be 147 tons per 

day of VOC emissions and 165 tons per day of NOX emissions for the Sacramento 

nonattainment area. The base year emissions are used to forecast future year 

inventories by using socio-economic growth indicators and the post-2002 emission 

reduction effects of existing control strategies. Also, potentially available pre-2002 

emission reduction credits (ERCs) are included as additional growth in future years to 

ensure that their use will not be inconsistent with the reasonable further progress and 

attainment targets.

Tables 1-1 and 1-2 summarize the VOC and NOX emissions inventory for the 

Sacramento nonattainment area by the four major emission categories. The VOC and 

NOX emission forecasts out to 2018 show significant declines in mobile source 

emissions, despite increasing population, vehicle activity, and economic development in 

the Sacramento region.

Table 1-1

Emissions Inventory of Volatile Organic Compounds (VOC)

Sacramento Nonattainment Area (tpd)

Emission Category 2002 2014 2017 2018

Stationary Sources 22 26 27 27

Area-Wide Sources 32 30 30 31

On-Road Motor Vehicles 52 21 17 15

Other Mobile Sources 41 28 25 24

Total 147 104 99 98

Notes: – ERCs are included in the 2014, 2017, and 2018 inventories.

– Totals may not add exactly due to rounding.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Executive Summary

Page 1-5

Table 1-2

Emissions Inventory of Nitrogen Oxides (NOX)

Sacramento Nonattainment Area (tpd)

Emission Category 2002 2014 2017 2018

Stationary Sources 12 13 12 12

Area-Wide Sources 3 3 3 3

On-Road Motor Vehicles 99 46 37 34

Other Mobile Sources 50 28 27 25

Total 165 90 78 74

Notes: – ERCs are included in the 2014, 2017, and 2018 inventories.

– Totals may not add exactly due to rounding.

1.5 Air Quality Modeling Analysis

Updated photochemical air quality grid modeling was developed to simulate base case 

episodes of high ozone formation as part of the extensive air monitoring and data 

analysis conducted for the 2000 Central California Ozone Study. The air quality model 

was then run with 2002 baseline year emissions and future year emissions forecasts 

(including VOC and NOX ERCs) to see if the ozone standard would be attained with

existing control strategies. The relative decline in future ozone concentrations shown in 

the photochemical modeling results predicted attainment at all ozone monitors in 2018 

except for two sites (Cool and Folsom) located in the eastern part of the Sacramento 

region.

Additional air quality modeling runs of across-the-board emission reduction scenarios 

were conducted. The air quality modeling analysis shows that attainment can be 

reached by 2018 with different combinations of VOC and NOX control. The modeling 

results indicate that both VOC and NOX reductions provide ozone benefits in the 

Sacramento region, but on a ton for ton basis NOX reductions provide greater ozone 

benefits than VOC reductions. More specific conclusions regarding attainment targets

for the Sacramento region’s peak ozone monitoring site at Cool are provided in the 

attainment demonstration evaluation.

1.6 Proposed Regional and Local Control Measures

The Sacramento SIP control strategy relies on the following components:

1. Reductions from existing control measures and adopted rules,

2. Reductions from new state and federal regulations, and

3. Reductions from defined new SIP local and regional measures.

The proposed SIP emissions control strategy includes reductions of both VOC and NOX

air pollutants. A single NOX pollutant strategy is not appropriate because, even though 

VOC measures are not as effective as NOX, they still provide needed reductions. 

Moreover, many existing statewide and local control programs will inherently achieve 

reductions from both ozone precursors.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Executive Summary

Page 1-6

EPA’s final 8-hour ozone implementation rule (pursuant to section 172(c)(1) of the 

Clean Air Act) requires the attainment SIP submittal to include adopting all reasonably 

available control measures (RACM) necessary to demonstrate attainment as 

expeditiously as practicable and to meet any RFP requirements. EPA’s RACM policy 

indicates that areas should consider all candidate measures that are potentially 

reasonably available. Sources of potentially reasonable measures include measures 

adopted in other nonattainment areas, measures that the EPA has identified in 

guidelines or other documents, and any measures that have been suggested for the 

particular nonattainment area during a public comment period.

Areas should consider all reasonably available measures for implementation in light of 

local circumstances. However, areas need only adopt measures if they are both 

economically and technologically feasible and cumulatively will either advance the 

attainment date by one year or more or are necessary for RFP. This plan contains 

required reasonably available control measures.

The total emission reductions from the new measures are an enforceable commitment 

in the SIP and provide a buffer for attainment. While the proposed regional and local 

control measures include estimates of the emission reductions from each of the 

individual measures, it is important to note that the commitment is to achieve the total 

emission reductions necessary to attain the federal standards. Therefore, if a particular 

measure or a portion thereof is found infeasible or does not get its expected emission 

reductions, each air district still commits to achieving the total aggregate emission 

reductions, whether this is realized through additional or surplus reductions from the 

other adopted measures, from alternative control measures, or incentive programs.

Although the regional and local commitment is to the "total emission reductions," for 

purposes of transportation conformity, an explicit commitment is made to the reductions 

associated with the on-road mobile source incentive program. Also the urban forest 

control measure, SMAQMD-1, is an emerging measure. Because of the uncertainties 

associated with implementation and validation of this urban forest measure, the 

emission benefits from this strategy are not included in the attainment or reasonable 

further progress demonstrations.

If an infeasibility finding is made for a control measure or a portion thereof in the future, 

the region's SIP commitment can be adjusted downward. For purposes of SIP 

commitment, infeasibility means that the proposed control technology is not reasonably 

likely to be available by the implementation date needed, or achievement of the 

emission reductions by that date is not cost-effective or technologically feasible because 

of local circumstances.

The following Table 1-3 contains a summary of the proposed new regional and local 

control measures and expected VOC and NOX emission reductions for the Sacramento 

nonattainment area for the 2018 attainment demonstration year. Emission benefits from 

these new committal measures are estimated to provide reductions of 3 tons per day of 
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Executive Summary

Page 1-7

VOC and 3 tons per day of NOX in 2018. Some of these new local measures will be 

adopted by the end of 2008, and emission benefits from just these adopted new 

measures are estimated to provide reductions of 1 ton per day of VOC in 2018.

Table 1-3

Summary of New Regional and Local Proposed Control Measures

Sacramento Nonattainment Area

Control Measure Name 2018 Emission Reductions 

(tpd)

VOC NOX

Regional Non-regulatory Measures

Regional Mobile Incentive Program – On-road <0.1 0.5

Regional Mobile Incentive Program – Off-road <0.1 <0.1

Spare The Air Program <0.1 <0.1

SACOG Transportation Control Measures - -

Urban Forest Development Program 0 - 0.2 -

Total Regional Non-regulatory Measures* 0.1 0.5

Local Regulatory Measures

Architectural Coating 1.5 -

Automotive Refinishing 0.2 -

Degreasing/Solvent Cleaning 0.7 -

Graphic Arts na -

Miscellaneous Metal Parts and Products <0.1 -

Natural Gas Production and Processing 0.1 -

Boilers, Steam Generator, and Process Heaters - 0.2

IC Engines - 0.0

Large Water Heaters and Small Boilers - 0.2

Total Local Regulatory Measures* 2.6 0.5

Total Reductions* 2.7 1.1

Notes: Numbers are truncated to one decimal place. na = not available

*Total reductions are summed from untruncated values. See summary table in Appendix C – Proposed Control Measures.

The following Table 1-4 contains a summary of SACOG transportation control measures

(TCMs) that are included in the Sacramento region’s federal 8-hour ozone plan. The 

TCMs include new and continuing projects and funding programs.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Executive Summary

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Table 1-4

Summary of SACOG Transportation Control Measures

New and Continuing Projects and Funding Programs

TCM Name and (ID) Implementing 

Agency

Implement or 

Completion 

Date

VOC

Reduction

(Tons/Day)

NOX

Reduction

(Tons/Day)

Intelligent Transportation Systems 

(ITS) Projects

Arden Way Smart Corridor (ITS-1) City of Sac - Dept of 

Transportation 2008 --- ---

Sacramento Traffic Operations 

Center (ITS-2)

City of Sac - Dept of 

Transportation 2009 --- ---

STARNET Implementation (ITS-4) SACOG 2009 --- ---

Park and Ride Lots / Transit Centers

El Dorado Central Park and Ride 

Facility (TF-1)

El Dorado County 

Transit 2009 --- ---

Improvements to Loomis Multimodal 

Center (TF-2)

Town of Loomis –

Dept of Public Works 2010 --- ---

13th and 16th St :Light Rail Station 

Improvements (TF-3)

Sac Regional Transit 

District 2009 --- ---

Transit Service Funding Programs

Transit Vehicle Acquisitions (TR-1) Various Agencies Various 

Dates --- ---

Transit Operations (TR-2) Various Agencies Various 

Dates --- ---

Other Specific Funding Programs

Freeway Service Patrol (AQ-1) Sac Transportation 

Authority Through 2018 --- ---

SECAT Program (AQ-2) SMAQMD Through 2018 ---

a

---

a

Spare The Air Program (AQ-3) SMAQMD Through 2018 ---

b

---

b

MTP Regional Funding Programs

Air Quality Funding Program (FP-1) Various Agencies Through 2018 --- ---

Bicycle and Pedestrian Funding 

Program (FP-2) Various Agencies Through 2018 --- ---

Transportation Demand 

Management Funding Program (FP3)Various Agencies Through 2018 --- ---

Community Design Funding 

Program (FP-4) Various Agencies Through 2018 --- ---

Miscellaneous Projects

Light Rail Grade Separation at Watt 

Ave and Folsom Blvd (M-2)

Sac County – Dept of 

Transportation 2009 --- ---

Dry Creek Parkway Trail Phase 1 Sac County – Dept of 

Transportation 2011 --- ---

Total Emission Reductions --- ---

a SECAT emission reductions are assumed to be included in SMAQMD mobile source control measure ONMSHD-1.

b Spare The Air emission reductions are assumed to be included in SMAQMD control measure TCM-ONMSED-1.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Executive Summary

Page 1-9

1.7 Attainment Demonstration

Attainment of the 1997 8-hour ozone NAAQS is evaluated for a 2018 “severe” 

classification scenario, based on modeling results for the peak ozone site (Cool) in the 

region. The modeled VOC and NOX emission forecasts for 2018 incorporate growth 

assumptions and the estimated reductions associated with the existing control strategy.

The photochemical modeling results were used to estimate the percent reductions 

needed from the 2018 emission forecasts in order to achieve the 1997 federal 8-hour 

ozone standard (84 ppb).

The emissions reduction from new measures is shown in Table 1-5. These future new 

committal measures provide a buffer in the attainment demonstration. It is anticipated 

that the attainment would be achieved by the 2018 deadline even if there is a reduction 

in their emission benefits. The attainment demonstration assessment for the 

Sacramento nonattainment area is summarized in Table 1-5.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Executive Summary

Page 1-10

Table 1-5 Summary of Attainment Demonstration for 8-Hour Ozone NAAQS 2018 

“Severe” Classification Scenario

Sacramento Nonattainment Area VOC (tpd) NOX (tpd)

Summary of 2009 Plan Attainment Demonstration

A) 2002 Planning Emissions Inventory 1160.3 196.1

B) 2018 Planning Emissions Inventory with Existing Controls 1121.1 104.1

C) Attainment Emission Reduction in percentage 23.3% 12.5%

D) SIP Emissions Target: Line B × (1 – Line C) 117.1 91.1

E Percentage Emission Reduction Required for Attainment: 

( 1 – (Line D ÷ Line A) ) × 100% 27.0% 53.6%

Revised Emissions Targets

F) Updated 2002 Inventory 3146.7 164.8

G) Updated SIP Emissions Target: Line F × ( 1 – Line E ) 107.1 76.5

Revised Attainment Demonstration

H) Updated 2018 Inventory 397.7 73.9

I Motor Vehicle Emissions Budgets Safety Margin 41 3

J) Emission Reductions in 2018 from Remaining Regional/Local Control 

Measures 5,7 2.7 1.1

K Emissions Reductions in 2018 from Remaining State/Federal Control 

Measures 6,7 5.7 0.3

L) Total Emissions in 2018 with All Remaining Controls:

( Line H + Line I - Line J – Line K )

90.3 75.5

M) Is Attainment Demonstrated? (Is Line L ≤ Line G?) Yes

1. The 2009 inventory is shown in Appendix A8.

2. The percent emission reduction targets for attainment are based on modeling results. Figure 8-1 

Point A.

3. Chapter 5. Tables 5-2 and 5-3 include ERCs (ERC details are in Tables 5-4 and 5-5).

4. Chapter 11 Table 11-1

5. Appendix C, Table of Emission Reductions by Air District, Page C-5.

6. Chapter 7. Table 7-2, sum of expected emission reductions from New Emission Standards for 

Recreational Boats and Expanded Off-Road Rec. Vehicle Emission Standards.

7. These reductions provide a buffer for meeting attainment targets.

1.8 Transport Analysis

The air quality in the Sacramento region is impacted by pollutant transport from the San 

Francisco Bay Area. Delta breezes carry air pollutants from upwind Bay Area emission 

sources into the Sacramento region, and these pollutants may contribute to ozone 

formation during the same day or the following days. The California Air Resources 

Board has determined that the relative impact from this Bay Area transport can be 

considered overwhelming, significant, or inconsequential on various days5, depending 

 

5 California Air Resources Board, “Ozone Transport: 2001 Review”, April 2001.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Executive Summary

Page 1-11

on meteorological conditions. CARB has also made findings that pollutant transport 

from the San Joaquin Valley can have significant or inconsequential impact6on air 

quality in the Sacramento region.

States are responsible for submitting SIPs for all areas of their State and need to 

demonstrate attainment in all areas addressing intrastate transport where appropriate.

The photochemical grid modeling study includes the northern and central regions of 

California in the modeling domain, and was used to address and account for air 

pollutant transport impacts among the San Francisco Bay Area, San Joaquin Valley, 

Sacramento Valley, and Mountain Counties air basins.

CARB modeling for the attainment demonstration for the Sacramento nonattainment 

area used domain-wide emission reductions to characterize future ozone reductions at 

peak ozone monitoring stations. Therefore, for our area to attain, reductions in 

forecasted emissions necessary and committed to in Sacramento must also be 

achieved in the areas that significantly impact the region. In other words, the attainment 

demonstration for the Sacramento nonattainment area is predicated on the San

Francisco Bay Area and the San Joaquin Valley also achieving an equivalent additional 

percent reduction of VOC and NOX emissions in their forecasted 2018 inventories. The 

reductions could come from either state or upwind regions’ local measures, but we 

understand that CARB has committed to address the reduction requirement by 

implementing the new state measures statewide, which are expected to achieve similar

reductions in the Bay Area and San Joaquin Valley.

In addition, pollutant transport from the Sacramento region can potentially impact the air 

quality in other regions under certain meteorological conditions. For example, CARB 

analyses have determined that ozone violations at the Grass Valley monitoring station 

in Nevada County are considered to be overwhelmingly due to transport from the 

Sacramento region.7 Emission reduction strategies in the Sacramento region will benefit 

their efforts to attain the federal ozone standards.

1.9 Weight-of-Evidence Determination

Attainment demonstrations based on photochemical modeling can be strengthened by 

supplemental evidence from additional modeling analyses and from considering 

modeling outputs other than the attainment test results. More diverse non-modeling and 

observational methods analyzing air quality, meteorological, and emissions data can 

also be used to corroborate the modeling predictions. EPA guidance8specifies that a 

comprehensive weight-of-evidence approach should be undertaken to support the 

modeled attainment demonstration.

 

6

Ibid.

7

Ibid.

8

“Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals 

for Ozone, PM2.5, and Regional Haze” (EPA, April 2007, p. 98-109).
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Executive Summary

Page 1-12

Since 1999, the number of area-wide exceedance days has decreased by over 10%.

The ozone design value has decreased by 5%. A smaller portion of the nonattainment 

region violates the 1997 federal ozone standard, and the western most and eastern 

most portions of the region attain. Analyses show that these improvements are due to 

emissions reductions, not favorable weather conditions.

The overall conclusions of the weight-of-evidence analyses support the attainment 

demonstration. The ozone modeling concluded that NOX reductions will be critical to 

reaching attainment. The additional weight-of-evidence analyses looked at three areas:

(i) the general decline in emissions, (ii) ambient air pollutants, and (iii) ozone 

concentration trend indicators. The ozone concentration analyses included adjustments 

for meteorology. These weight-of- evidence analyses found that each of these areas are 

improving over time, consistent with the overall NOX and VOC emission control strategy

reducing peak ozone in the region, and support the conclusion that the region will attain 

by 2018.

1.10 Transportation Conformity and Emission Budgets

Under the federal Clean Air Act, federal agencies may not approve or fund 

transportation plans and projects unless they are consistent with state air quality 

implementation plans (SIPs). Conformity with the SIP requires that transportation 

activities not cause new air quality violations, worsen existing violations, or delay timely 

attainment of the national ambient air quality standards (NAAQS). Conformity 

regulations state that emissions from transportation plans and projects must be less 

than or equal to the motor vehicle emissions budgets established by reasonable further 

progress, attainment or maintenance plans (SIPs). (40 CFR 93.118)

Table 1-6 lists the proposed new transportation conformity budgets for the 2014, and 

2017 RFP milestone years, and the 2018 attainment analysis year for the Sacramento 

nonattainment area. The proposed budgets incorporate the recent on-road motor 

vehicle emission inventory factors of EMFAC2011, updated travel activity data, and 

latest regional and state control strategies.

Table 1-6

Proposed New Motor Vehicle Emission Budgets

Sacramento Nonattainment Area

NOX VOC

2014 2017 2018 2014 2017 2018

ARB Inventories for Conformity (Tons per 

Day) 46 37 34 21 17 16

Safety Margin 3 2 3 2 1 1

Budgets 49 39 37 23 18 17

*All motor vehicle emission budget years include regional incentive benefits. State control measure reductions are 

only included in 2018
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Executive Summary

Page 1-13

This ozone plan includes the updated on-road motor vehicle emissions and the 

proposed transportation budgets that assume vehicle activity levels based on the road 

and transit projects contained in the region’s 2013/16 Metropolitan Transportation

Improvement Program on SACOG’s new SACSIM regional travel forecasting model to 

estimate future traffic volumes in the 6-county Sacramento region.

The vehicle activity levels for the eastern part of Solano County in the Sacramento 

nonattainment area are based on MTP data from the Bay Area Metropolitan 

Transportation Commission (MTC).

If these proposed new motor vehicle emission budgets are determined to be adequate 

for transportation conformity purposes by EPA, future transportation plans will need to 

conform to them. The Metropolitan Planning Organizations, SACOG and MTC, must 

ensure that the aggregate transportation emissions in the region stay below these levels 

when approving new metropolitan transportation plans and transportation improvement 

programs, even if the mix of projects changes or growth increases. These new, 

adequate 8-hour MVEBs will remain in effect until other budgets are found adequate or 

approved by EPA.

Vehicle Miles Traveled Offset (VMT Offset)

In early 2011, EPA’s interpretation of the Clean Air Act VMT offset requirements 

(Section 182(d)(1)(A)) was challenged in the U.S. Court of Appeals for the 9th Circuit.9

The ruling effectively requires severe and extreme nonattainment areas, including 

Sacramento, to submit VMT offset demonstrations.

A detailed VMT offset demonstration was prepared by California Air Resources Board 

and is included in Appendix F – Motor Vehicle Emission Budgets and VMT Offset 

Demonstration.

1.11 General Conformity

General conformity is the federal regulatory process for preventing major federal actions 

or projects from interfering with air quality planning goals. Conformity provisions ensure 

that federal funding and approval are given only to those activities and projects that are 

consistent with state air quality implementation plans (SIPs). Conformity with the SIP 

means that major federal actions will not cause new air quality violations, worsen 

existing violations, or delay timely attainment of the national ambient air quality 

standards (NAAQS). Examples of general federal actions that may require a conformity 

determination include, but are not limited to, the following: leasing of federal land; 

private construction on federal land; reuse of military bases; airport construction and 

expansions, and construction of federal office buildings.

 

9

Association of Irritated Residents v EPA, (9th Cir. 2011, reprinted as amended on January 27, 2012, 

632 F. 3d 584, at 596-597).
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Executive Summary

Page 1-14

A federal agency may demonstrate conformity by showing that the total of direct and 

indirect emissions from the action is accounted for in the applicable SIP’s attainment or 

maintenance demonstration. Therefore, the updated emissions inventory in this 8-hour 

ozone attainment demonstration plan would be applicable for general conformity 

purposes. Specific emission budgets for airport operations are identified for future 

years.

1.12 Reasonable Further Progress Demonstration

The federal 8-hour ozone regulations10 require that areas classified as “serious or

above” submit a reasonable further progress (RFP) demonstration plan that provides for

at least 3% average annual reductions of VOC (and/or NOX) emissions every 3-year 

period after 2008 out to the attainment year. The RFP demonstration must fully account 

for emissions growth when calculating the net emission reductions.

In February 2006, the Sacramento region submitted an early 8-hour ozone RFP plan to 

EPA demonstrating an 18% reduction from 2002-2008 for the Sacramento 

nonattainment area with existing control strategies. In addition, the early RFP plan 

included an updated emission inventory and set new motor vehicle emission budgets for 

2008, which EPA found to be adequate for transportation conformity purposes.11

Consequently, this Sacramento Regional 8-Hour Ozone Attainment and RFP Plan does 

not include a 2002-2008 RFP demonstration.

The RFP evaluation in this ozone plan is based on the emission inventory forecasts,

which assume expected growth rates and current control measures. The 3-year RFP 

demonstrations are achieved through VOC and NOX emission reductions for the 

milestone years of 2014, 2017, and the 2018 attainment analysis year. Figure 1-3 

shows the percentages of VOC reductions and NOX substitution that are used to meet 

the RFP reduction targets.

 

10 Federal Register, November 29, 2005, p. 71634.

11 Federal Register, March 14, 2006, p. 13124 (effective date March 29, 2006).
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Executive Summary

Page 1-15

Figure 1-3

Summary of Reasonable Further Progress Demonstrations

Sacramento Nonattainment Area

1.13 Conclusions

1. Since 1990, there has been a declining trend in 8-hour ozone exceedances and 

ozone design value concentration, with the most frequent and highest violations 

occurring at eastern monitoring sites (e.g., Cool, Folsom, Placerville, Auburn).

2. The VOC and NOX emissions inventory forecasts through 2018 show significant 

declines in mobile source emissions, despite increasing population, vehicle 

activity, and economic development in the Sacramento region.

3. The air quality modeling analysis indicates additional emission reductions are 

needed to achieve attainment by 2018, and NOX reductions on a ton for ton basis 

would be more effective at reducing high ozone in the region than VOC 

reductions.

4. New regulatory and non-regulatory VOC and NOX control measures at the 

regional and local level are proposed for adoption in this plan, which includes 

commitments to adopt required reasonably available control measures (RACM).

5. The combined reductions from new state and federal control measures and from 

new regional and local proposed control measures contained in this plan provide 

the additional VOC and NOX emission reductions needed to demonstrate 

attainment by the 2018 “severe” classification deadline.

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

 2014 RFP 2017 RFP 2018 RFP Reduction From Adjusted 2002 Baseline in Milestone Year

NOx Reduction Surplus

3% Contingency

NOx Substitution

VOC Reductions

RFP Reduction Target
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Executive Summary

Page 1-16

6. New transportation conformity emission budgets are being proposed for the 

Sacramento region, which incorporate the recent EMFAC2007 motor vehicle 

emission factors, updated travel activity data, and latest control strategies.

7. Reasonable further progress demonstrations for the milestone years of 2014, 

2017, and the 2018 attainment analysis year are achieved by a combination of 

VOC and NOX reductions.

8. Future ozone planning efforts will include the preparation of progress (milestone) 

reports to assess reasonable further progress.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Background Information and Plan Development Overview

Page 2-1

2 BACKGROUND INFORMATION and PLAN DEVELOPMENT OVERVIEW

2.1 Ozone Health Effects

Air pollution or “smog” is composed of many different gaseous and particulate 

pollutants, which can create a regional haze reducing atmospheric visibility. Groundlevel ozone, a colorless gas, is a major component of photochemical smog. Since 

ozone is formed especially in the presence of strong sunlight, ambient ozone 

concentrations are more problematic during May through October.

Ozone is a strong irritant that adversely affects human health. Breathing air containing 

ozone can reduce lung function and increase respiratory symptoms, thereby 

aggravating asthma, bronchitis, or other respiratory conditions including chest pains and 

wheezing. As documented by the EPA in their 2006 Criteria Document12 for ozone, both 

short-term and long-term exposure to ozone can irritate and damage the human 

respiratory system, resulting in:

 increased susceptibility to respiratory infections;

 increased risk of cardiovascular problems such as heart attacks and strokes;

 increased doctors visits, hospitalizations, and emergency room visits;

 increased school absenteeism; and

 an increase in mortality/premature deaths, especially in people with heart and lung 

disease.13

The adverse effects of ozone are not just limited to humans. Ozone can also cause 

damage to crops and natural vegetation by acting as a chemical oxidizing agent.

Ground-level ozone is one of the air pollutants regulated by the federal and state 

government. Reducing ozone to levels below state and federal standards is one of the 

primary goals of the air districts.

2.2 Ozone Formation and Precursor Pollutants

Ozone is not directly emitted into the atmosphere. It is a pollutant formed in the 

atmosphere through complex chemical reactions involving volatile organic compounds 

(VOC) and nitrogen oxides (NOX) in the presence of sunlight. Because of this, VOC and 

NOX are known as ozone “precursors.”

VOC and NOX air pollutants are emitted by many types of sources, including on-road 

and off-road combustion engine vehicles, power plants, industrial facilities, gasoline 

 

12 “Air Quality Criteria for Ozone and Related Photochemical Oxidants” (EPA, February 2006) –

http://www.epa.gov/ncea.

13 Staff Report Revisions to the “Review of the California Ambient Air Quality Standard for Ozone” 

(California Air Resources Board, October 27, 2005, p. 1-1 and 1-2).
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Background Information and Plan Development Overview

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stations, organic solvents, and consumer products. VOC pollutants are also known as 

reactive organic gases (ROG).

2.3 Clean Air Act and Prior Federal 1-Hour Ozone Standard

The first comprehensive national air pollution legislation was the federal Clean Air Act 

(CAA) of 1970. The CAA was amended in 1977 to require local plans for meeting 

national ambient air quality standards. To protect the public from unhealthy ozone 

levels, the U.S. Environmental Protection Agency (EPA) revised the national ambient 

ozone standard in 1979 to a concentration of 0.12 parts per million averaged over one 

hour14.

The federal Clean Air Act Amendments of 1990 included new attainment deadlines and 

planning requirements. In 1991, the Sacramento region was initially designated by EPA 

as a “serious” nonattainment area for the 1-hour ozone standard with an attainment 

deadline of 1999. Attainment demonstration plans for the 1-hour ozone standard were 

due to EPA by November 15, 1994.

2.4 1994 Sacramento Area Regional Ozone Attainment Plan

Sophisticated air quality computer modeling was used to simulate future ozone 

formation and evaluate the effectiveness of emission control scenarios. Computer 

modeling did not project attainment by the 1999 deadline. As a result, the 1994 

Sacramento Area Regional Ozone Attainment Plan was prepared to demonstrate that a 

combined strategy controlling emissions of volatile organic compounds and nitrogen

oxides could achieve attainment of the federal 1-hour ozone standard by 2005.

Commitments were made to develop and implement new regional, state, and federal 

control measures to reduce emission levels below the amounts shown by the modeled 

attainment demonstration.

In response to the 1994 SIP relying on a 2005 attainment date, EPA approved the 

attainment plan and voluntary request for nonattainment reclassification from a “serious” 

area to a “severe” area, effective June 1, 199515. The control measures implemented 

from the 1994 SIP are incorporated into the existing control strategies and reflected in 

future emission forecasts. EPA has recognized the Sacramento Region attained the 1-

hour ozone standard16.

 

14 One-hour ozone standard violation criterion defined as no more than 3 daily exceedances (>124 ppb) 

over 3 years at a monitoring site.

15 “California, Sacramento Ozone Nonattainment Area, Reclassification to Severe” (Federal Register, 

April 25, 1995).

16 Federal Register, October 12, 2012, p. 64036-64039.
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2.5 Federal 8-Hour Ozone Standard

In July 1997, EPA promulgated an 8-hour standard for ozone17. This change lowered 

the health-based standard for ambient ozone from 0.12 parts per million of ozone 

averaged over one hour to 0.08 parts per million of ozone averaged over eight hours. In 

general, the 8-hour standard is more protective of public health and more stringent than 

the federal 1-hour standard.

Court Challenges and Findings

The American Trucking Association challenged this standard in the Washington D.C. 

Court of Appeals. In May 1999, the Court ruled that EPA’s delegation of authority and 

implementation approach were improper, and remanded the standard. EPA appealed 

this decision, and in February 2001, the U.S. Supreme Court upheld the 8-hour ozone 

standard, but maintained that EPA’s implementation approach was unreasonable. In 

June 2003, EPA proposed a revised implementation strategy for the 8-hour ozone 

standard to address the Supreme Court findings, and finalized phases 1 and 2 of the 

rulemaking in the April 30, 2004 Federal Register and November 29, 2005 Federal 

Register, respectively.

The Phase 1 rule addressed such topics as: 1) classification and attainment deadlines, 

2) revocation of the 1-hour ozone standard, 3) transitioning to the 8-hour ozone rule, 

and 4) control measure anti-backsliding provisions18. The Phase 2 rule addressed 

remaining elements of implementing the 8-hour ozone standard, such as: 1) reasonably 

available control technology and measures, 2) reasonable further progress, 3) modeling 

and attainment demonstrations, and 4) new source review.

Several parties representing various interest groups challenged different aspects of the 

Phase 1 rule in the D.C. Court. On December 22, 2006, the Court decided in favor of 

some of the petitioners but upheld parts of EPA’s action. The Court determined that 

EPA could revoke the 1-hour ozone standard and did not dispute EPA’s classification 

scheme for the new 8-hour ozone standard using the approach promulgated under the 

1990 CAA Amendments.19 The Court then found that EPA did not comply with the 

Clean Air Act anti-backsliding provisions in section 172(e), under which 8-hour ozone 

nonattainment areas remain subject to control measure commitments that applied under 

the 1-hour ozone standard. The anti-backsliding issues included:

1. The Phase 1 rule provided that NSR levels be based on new 8-hour ozone 

classifications, rather than maintaining the more restrictive 1-hour ozone NSR 

levels that were applicable to some areas.

 

17 “National Ambient Air Quality Standards for Ozone” (Federal Register, July 18, 1997, p. 38855-38896).

18 Section 172(e) of the Clean Air Act provides that in the event EPA relaxes a primary standard, controls 

cannot be less stringent than the controls applicable to nonattainment areas before the relaxation.

19 Court allowed 8-hour ozone classifications using Clean Air Act, Title 1, part D, subpart 2, but not using 

subpart 1.
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2. The Phase 1 rule deferred Clean Air Act, section 185 fees that would have been 

enforced for areas that did not attain the federal 1-hour ozone standards beginning 

in 2005.

3. The Phase 1 rule allowed states to remove 1-hour ozone plan contingency 

measures that have not been triggered, or to modify the trigger for measures to 

reflect the 8-hour standard.

4. The Phase 1 rule no longer required conformity determinations for the 1-hour 

ozone standard.

EPA requested a rehearing by the D.C. Circuit Court of Appeals. On June 8, 2007, the 

Court rejected the rehearing of classification and anti-backsliding issues. However, the 

Court clarified its reference to 1-hour ozone conformity determinations and limited the 

scope of its previous decision vacating the Phase 1 rule by stating that only those 

portions of the rule specifically challenged by the petitioners were affected by the ruling.

Additionally, the Court urged EPA to promptly promulgate a revised rule.

Finally, on January 14, 2008, the Supreme Court denied two industry petitions to review 

the D.C. Circuit Court of Appeals’ decision on EPA’s Phase 1 rule. These two petitions 

challenged the Circuit Court’s interpretation of the Clean Air Act’s anti-backsliding 

provisions, arguing in part that these provisions should not apply when EPA strengthens 

a NAAQS.

This 8-hour ozone attainment plan assumes that upon new action by EPA in response 

to the Court’s remand, EPA will not modify the 8-hour ozone classification scheme and 

attainment deadlines.

Since 1992, EPA applied its longstanding interpretation of CAA section 182(d)(1)(A)

requirement that allowed a state to conclude that no further transportation control 

measures (TCMs) are necessary if aggregate motor vehicle emissions are projected to 

decline each year from the base year of the plan to the attainment year.

In early 2011, EPA’s interpretation was challenged in the U.S. Court of Appeals for the 

9th Circuit.20 The ruling effectively requires severe and extreme nonattainment areas, 

including Sacramento, to submit the VMT offset demonstrations.

In August 2012, EPA released guidance21 in response to the Court’s opinion. This 

guidance indicates that technology improvements such as vehicle technology

improvements, motor vehicle fuels, and other control strategies that are transportation

related could be used to offset increases in emissions due to VMT. This guidance also

sets out a methodology for demonstrating achievement of the VMT offset requirement.

 

20 Association of Irritated Residents v EPA, (9th Cir. 2011, reprinted as amended on January 27, 2012, 

632 F. 3d 584, at 596-597)

21 Implementing Clean Air Act Section 182(d)(1)(A): Transportation Control Measures and Transportation 

Control Strategies to Offset Growth in Emissions Due to Growth in Vehicle Miles Travelled (EPA, August 

2012).
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This Plan contains a vehicle miles travelled offset demonstration that satisfies Clean Air 

Act requirements under section 182(d)(1)(A), using the methodology outlined in EPA’s 

August 2012 guidance entitled “Implementing Clean Air Act Section 182(d)(1)(A): 

Transportation Control Measures and Transportation Control Strategies to Offset 

Growth in Emissions Due to Growth in Vehicle Miles Travelled.”

New 8-Hour Ozone NAAQS

On March 12, 2008, EPA promulgated a revised 8-hour ozone NAAQS22 of 0.075 parts 

per million, based on a review of new health studies. However, the 1997 8-hour 

standard remains in effect, as do the SIP requirements and implementation rules for 

that standard, including this Plan update requirement. Planning requirements for the 

new 8-hour ozone NAAQS will be identified and addressed in the future.

2.6 Development of the Sacramento Regional 8-Hour Ozone Attainment and 

Reasonable Further Progress Plan

This ozone attainment plan was developed for the Sacramento region by the five air 

districts in the nonattainment area with participation from the California Air Resources 

Board (CARB), the Sacramento Area Council of Governments (SACOG), and the Bay 

Area Metropolitan Transportation Commission (MTC). The five local air districts include 

the Sacramento Metropolitan Air Quality Management District (SMAQMD), the YoloSolano Air Quality Management District (YSAQMD), the Placer County Air Pollution 

Control District (PCAPCD), the El Dorado County Air Quality Management District 

(EDCAQMD), and the Feather River Air Quality Management District (FRAQMD).

SACOG and MTC23 are the metropolitan planning organizations (MPO) for 

transportation planning in the Sacramento region.

Because of recent changes in the long range transportation plans, SACOG was a key 

contributor in the development of the updated motor vehicle emissions inventory and 

transportation control measures. CARB staff also conducted the photochemical 

modeling and provided information regarding state and federal control measures, 

weight-of-evidence analyses, motor vehicle emissions budgets, and the reasonable 

further progress demonstration.

Several committees provided input on technical and policy issues during the 

development of the Sacramento Regional 8-Hour Ozone Attainment and Reasonable 

Further Progress Plan. The Interagency Coordination Committee (ICC) consisted of 

participants from the various agencies mentioned above and from the California 

Department of Transportation, EPA, and Federal Highways Administration. The ICC 

was assembled to coordinate the efforts of the local, state, and federal governmental 

agencies directly involved in the preparation and/or review of the ozone plan.

 

22 “National Ambient Air Quality Standards for Ozone” (Federal Register, March 27, 2008, p. 16436-

16514).

23 MTC is the MPO for the east Solano County portion of the Sacramento nonattainment area.
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A SIP coordination working group was formed from participants of the Central California 

Ozone Study Technical Committee to focus on evaluating and improving the modeling 

and emissions inventory. Also, a subcommittee of the air districts in the Sacramento 

nonattainment area met periodically to coordinate the development of the various 

potential local VOC and NOX emission control measures needed in the SIP attainment 

strategy. In addition, the Regional Air Pollution Control Officers Committee for the 

Sacramento region was used to discuss and coordinate SIP topics and concerns.

2.7 Public Input and Review Process

Existing public working groups were used to disseminate information and seek input 

from a wide variety of key community stakeholders during the development process of 

the draft plan. These committees included the Sacramento Cleaner Air Partnership, 

SACOG’s Climate and Air Quality Committee and Regional Planning Partnership, and 

the Chamber of Commerce’s Air Quality and Transportation Committee, who represent 

major business interests, environmental groups, transportation agencies, local 

governments, and other community organizations. In addition, representatives for the 

various Native American tribes in the Sacramento region were contacted and invited to 

participate in the public process to develop the draft plan.

In the fall of 2006, public workshops were held to solicit comments on potential control 

measures for the attainment demonstration. Additional public workshops were held 

early fall of 2008 to present information and receive comments on the draft Sacramento 

Regional 8-Hour Ozone Attainment and Reasonable Further Progress Plan. Finally, the 

Board of Directors for each of the air districts in the Sacramento nonattainment area 

held a public hearing prior to approving the plan. The 2013 technical amendments were 

noticed in each air district and the public hearing conducted by the SMAQMD Board of 

Directors.

2.8 Contents of 8-Hour Ozone Plan

This document includes the information and analyses to fulfill the federal 8-hour ozone 

attainment and reasonable further progress planning requirements for the Sacramento 

regional nonattainment area. This plan does not address state ozone planning 

obligations prescribed by the California Clean Air Act. This document relies on 

information about proposed state and federal control strategies that are included here 

by reference. This document does not describe in detail or evaluate those strategies.

For more information about emission control strategies implemented by the California 

Air Resources Board or other state agencies, contact the California Air Resources 

Board, P.O. Box 2815, Sacramento, CA 95812-2815 or see 

http://www.arb.ca.gov/planning/sip/2007sip/2007sip.htm.

Chapter 1 is an executive summary of the 8-hour ozone plan. Chapter 2 provides an 

introduction that contains background information on ozone health effects, ozone 

formation, the federal ozone standards, and an overview of the plan’s development 

process. Chapter 3 explains the purpose of the attainment plan and defines federal 
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Clean Air Act 8-hour ozone requirements for the region. Chapter 4 analyzes and 

illustrates 8-hour ozone air quality trends in the Sacramento region. Chapter 5 presents 

the 2002 base year emissions inventory and the emission forecasts that are based on 

existing control strategies and growth assumptions.

Chapter 6 characterizes the air quality modeling simulations and predictions, and 

analysis of results for determining attainment emission targets. Chapter 7 identifies and 

evaluates the proposed new regional and local control measures that are needed to 

reduce future emissions. Some control measures may provide benefits for other air 

contaminants such as fine particles or greenhouse gases. This plan does not quantify 

those benefits. Chapter 8 shows the 8-hour ozone attainment demonstration for the 

Sacramento region using the emission forecasts, photochemical modeling results, and 

the proposed control strategy scenario. Chapter 9 discusses inter-basin pollutant 

transport issues and addresses transport assumptions included in the photochemical 

modeling. Chapter 10 discusses additional evidence supporting the attainment 

demonstration based on supplemental non-modeling data analyses of air quality and 

emission trends in conjunction with modeling results.

Chapter 11 documents the motor vehicle emissions budgets for transportation 

conformity purposes. This chapter also provides an analysis demonstrating that the

SFNA meets the vehicle miles traveled (VMT) Offset requirements under CAA section 

182(d)(1)(A). Chapter 12 explains general conformity requirements and provides 

estimates for forecasted airport emissions. Chapter 13 demonstrates how the 

reasonable further progress emission reduction requirements will be achieved. Finally, 

Chapter 14 summarizes the key points and major conclusions of this report, and

mentions expected future air quality planning efforts by the air districts.

Additional documentation for the more technical sections of the 8-hour ozone attainment 

plan is contained in the following Appendices:

A – Emissions Inventory

B – Photochemical Modeling

C – Proposed Control Measures

D – Transportation Control Measures 

E – Weight-of-Evidence Analyses

F – Motor Vehicle Emissions Budgets and VMT Offset Analysis

G – Reasonable Further Progress Demonstrations

H – Reasonably Available Control Measures (RACM) Analysis

I – Federal Clean Air Act Requirements
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3 FEDERAL CLEAN AIR ACT REQUIREMENTS

3.1 Purpose of a Federal Ozone Attainment Plan

In 2004, the Sacramento region was rated one of the four worst ozone air quality areas 

in the nation, based on the U.S. Environmental Protection Agency (EPA) designations 

and classifications24 for the 1997 8-hour ozone national ambient air quality standards 

(NAAQS)25. The Sacramento region was classified as a “serious” nonattainment area.

While air quality has improved, and the area met the 1-hour standard in 2009,

exceedances of the 8-hour ozone air quality standard continue to occur in many parts of 

the region. Emissions of air pollutants that contribute to the formation of ozone must be 

reduced significantly in order to attain the 8-hour NAAQS.

The federal 8-hour ozone implementation rules26 set new deadlines for attaining the 

ozone standard. The rules also set specific planning requirements to ensure that the 

attainment goal is met. Foremost among these requirements is adoption and 

implementation of an ozone attainment plan. This plan must identify a comprehensive 

strategy to reduce emissions needed for attainment by the mandated deadline. The 

rules and programs in a plan are then implemented over time to reduce the emissions 

that going into the air, reducing unhealthful concentrations of air pollutants, and helping 

areas reach federal air quality standards.

This Sacramento Regional 8-Hour Ozone Attainment and Reasonable Further Progress 

Plan was prepared to meet these requirements as part of California’s State 

Implementation Plan (SIP) update. The California SIP includes plans for each of the 

state’s nonattainment areas, along with rules, regulations, and other control measures 

adopted by air districts and the California Air Resources Board (CARB). After SIP 

updates are reviewed and approved by CARB, they are submitted to EPA for federal 

review and approval.

3.2 Federal Clean Air Act Requirements

The federal Clean Air Act (CAA) contains many SIP requirements for areas classified as 

a nonattainment area for 8-hour ozone. The CAA requirements applicable to 

nonattainment plan elements are outlined in Appendix I. SIP requirements for several 

basic plan elements are summarized in the following sections.

 

24 “Air Quality Designations and Classifications for the 8-Hour Ozone National Ambient Air Quality 

Standards” (Federal Register, April 30, 2004, p. 23858-23951) and EPA Website for “Classifications of 8-

Hour Ozone Nonattainment Areas” (http://www.epa.gov/oar/oaqps/greenbk/gnc.html), accessed March 2, 

2006.

25 “National Ambient Air Quality Standards for Ozone” (Federal Register, July 18, 1997, p. 38855-38896).

26 “Final Rule to Implement the 8-Hour Ozone National Ambient Air Quality Standard – Phase 1” (Federal 

Register, April 30, 2004, p. 23951-24000) and “Final Rule to Implement the 8-Hour Ozone National 

Ambient Air Quality Standard – Phase 2” (Federal Register, November 29, 2005, p. 71612-71705).
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3.3 New Source Review (NSR) and Other Permitting Requirements

Section 181(b)(3) of the Clean Air Act (CAA) permits a state to request that EPA 

reclassify or “bump-up” a nonattainment area to a higher classification and extend the 

time allowed for attainment. This bump-up process is appropriate for areas that must 

rely on longer term strategies to achieve the emission reductions needed for attainment.

On February 14, 2008, CARB on behalf of the air districts27 in the Sacramento 

nonattainment area requested a voluntary reclassification (bump-up) of the Sacramento 

Federal Nonattainment Area from a “serious” to a “severe” 8-hour ozone nonattainment 

area with an associated attainment deadline of June 15, 2019. EPA approved the 

reclassification, effective June 4, 2010 (75 FR 24409, May 5, 2010).

The region must meet requirements associated with the “severe” classification.

Pursuant to section 182(d) of the CAA, the New Source Review offset ratio of total VOC 

and NOX emission reductions to total increased emissions of such air pollutants must be 

at least 1.3 to 1 (instead of at least 1.2 to 1 for a serious classification).

Also, the emissions threshold for the definitions of a “major source” and a “major 

stationary source” are 25 tons per year of either VOC or NOX emissions.

3.4 Reasonably Available Control Technology (RACT) Requirements

The U.S. Environmental Protection Agency (EPA) published the final Phase 2 Rule to 

implement the 8-hour ozone air quality standard on November 29, 2005 (70 FR 71611).

Among the requirements of the Phase 2 Rule, a new section was added to the Code of 

Federal Regulations (40 CFR 51.912) that requires the District to submit a revision to 

the State Implementation Plan (SIP) that meets the Reasonably Available Control 

Technology (RACT) requirements for VOC and NOX in accordance with Sections 

182(b)(2) and 182(f) of the federal Clean Air Act. This requirement is known as the 

RACT SIP.

EPA defines RACT (44 FR 53762) as “the lowest emission limitation that a particular 

source is capable of meeting by the application of control technology that is reasonably 

available considering technological and economic feasibility.” Sections 182(b)(2) and 

182(f) of the Clean Air Act require the District to implement RACT for:

 Each category of VOC sources that is covered by a Control Techniques

Guidelines (CTG) document issued by EPA; and

 All major stationary sources of VOC and/or NOX.

The submittal deadline for RACT SIPs was September 15, 2006 (27 months after 

designation for the 8-hr ozone NAAQS). RACT SIPs for major sources under “serious” 

requirements were prepared and submitted by each district.

 

27 District action dates approving the reclassification request: SMAQMD 1-24-08; FRAQMD 2-04-08; 

EDCAQMD 2-05-08; YSAQMD 2-13-08; PCAPCD 2-14-08.
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For areas designated as “severe” nonattainment for the 8-hr ozone NAAQS, RACT 

control measures would apply to sources with emissions equal to or greater than 25

tons per year. Each air district will independently prepare and submit updated RACT 

SIPs as needed.

3.5 Reasonably Available Control Measures (RACM) Requirements

Section 172(c)(1) of the Clean Air Act states that SIP “plan provisions shall provide for 

the implementation of all reasonably available control measures as expeditiously as 

practicable (including such reductions in emissions from existing sources in the area as 

may be obtained through the adoption, at a minimum, of reasonably available control 

technology) and shall provide for attainment of the national primary ambient air quality 

standards.” In addition, EPA’s final 8-hour ozone implementation rule in 40 CFR 

51.912(d), adopted under section 172(c)(1) of the CAA, requires the attainment SIP 

submittal to include “a SIP revision demonstrating that it has adopted all RACM 

necessary to demonstrate attainment as expeditiously as practicable and to meet any 

RFP requirements.”

EPA’s RACM policy28,29 indicates that areas should consider all candidate measures 

that are potentially reasonably available. Sources of potentially reasonable measures 

include measures adopted in other nonattainment areas, measures that the EPA has 

identified in guidelines or other documents, and any measures that have been 

suggested for the particular nonattainment area during a public comment period.

Areas should consider all reasonably available measures for implementation in light of 

local circumstances. However, areas need only adopt measures if: (i) they are both 

economically and technologically feasible and cumulatively will advance the attainment 

date by one year or more, or (ii) are necessary for RFP. Furthermore, “EPA does not 

believe that Congress intended the RACM requirement to compel the adoption of 

measures that are absurd, unenforceable, or impracticable30.”

3.6 Vehicle Miles Travelled (VMT) Offset Requirement

Section 182(d)(1)(A) of the federal Clean Air Act applies to areas classified as severe or 

extreme nonattainment of the National Ambient Air Quality Standard (NAAQS) for 

ozone. The Sacramento Federal Ozone Nonattainment Area is currently designated as 

Severe-15, (75FR24409) and is subject to this requirement. A VMT offset demonstration 

 

28 “Final Rule to Implement the 8-Hour Ozone National Ambient Air Quality Standard – Phase 2” (Federal 

Register, November 29, 2005, p. 71659-71661).

29 “Guidance on the Reasonably Available Control Measures (RACM) Requirement and Attainment 

Demonstration Submissions for Ozone Nonattainment Areas” (EPA, December 1999).

30 ”General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990” (57 FR 

13498, April 16, 1992).
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was prepared in accordance with U.S. EPA’s guidance31 and is included as part of this 

plan.

3.7 Sacramento Nonattainment Area Designation

EPA made determinations regarding which areas violate the standard under the federal 

8-hour ozone regulations32, effective June 15, 2004. The nonattainment designation is 

based on whether the ozone design value concentration for any of the monitoring sites 

in the area exceeds the national ambient air quality standard33. A monitoring site’s 8-

hour ozone design value is calculated by averaging the annual fourth-highest daily 

maximum 8-hour average ozone concentrations over the most recent three years.

The Sacramento region is designated a nonattainment area, and includes all of 

Sacramento and Yolo counties and portions of Placer, El Dorado, Solano, and Sutter 

counties. See Figure 3-1 for a map of the 8-hour ozone Sacramento nonattainment area

(same boundaries as federal 1-hour ozone nonattainment area).

3.8 Nonattainment Classification and Attainment Deadline

Nonattainment areas are classified34 as marginal, moderate, serious, severe, or 

extreme areas depending on the magnitude of the highest 8-hour ozone design value 

for the monitoring sites in the nonattainment area. The Sacramento region was initially 

classified as a “serious” nonattainment area35 for the 8-hour ozone standard, with an 

attainment deadline of June 15, 2013 (i.e., 9 years after designation). This classification 

was based on the 8-hour ozone design value of 107 ppb at Cool, calculated from ozone 

concentrations monitored during 2001-2003.

Section 181(b)(3) of the Clean Air Act permits a state to request that EPA reclassify or 

“bump-up” a nonattainment area to a higher classification and extend the time allowed 

for attainment. Reclassification is appropriate for areas that must rely on longer term 

strategies to achieve the emission reductions needed for attainment. More stringent 

requirements are imposed with each higher classification level.

Since the Sacramento region needs to rely on the longer term emission reduction 

strategies from state and federal mobile source control programs, the 2013 attainment 

date cannot be met. Consequently, on February 14, 2008, CARB, on behalf of the air 

 

31 “Implementing Clean Air Act Section 182(d)(1)(A): Transportation Control Measures and Transportation 

Control Strategies to Offset Growth in Emissions Due to Growth in Vehicle Miles Travelled.”(EPA August 

2012)

32 “Air Quality Designations and Classifications for the 8-Hour Ozone National Ambient Air Quality 

Standards” (Federal Register, April 30, 2004, p. 23857-23951.

33 1997 federal 8-hour ozone standard = 84 ppb.

34 Sacramento’s classification was given by the more specific requirements of the subpart 2 provisions in 

the Clean Air Act.

35 “Air Quality Designations and Classifications for the 8-Hour Ozone National Ambient Air Quality 

Standards” (Federal Register, April 30, 2004, p. 23887.
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districts in the Sacramento region, submitted a letter to EPA requesting a voluntary 

reclassification of the Sacramento Federal Nonattainment Area from a “serious” to a 

“severe” 8-hour ozone nonattainment area with an extended attainment deadline of 

June 15, 2019.

3.9 Reasonable Further Progress Plan

Sections 172(c)(2), 182(b)(1), and 182(c)(2)(B) of the Clean Air Act include reasonable 

further progress (RFP) requirements for reducing emissions in ozone nonattainment 

areas. EPA’s 8-hour ozone planning implementation Phase 2 rule requires RFP 

reductions averaging at least 3% per year demonstrated in specific milestone years; 6 

years after the 2002 baseline year and every 3 years thereafter through attainment.

In February 2006, the Sacramento region submitted an early 8-hour ozone RFP plan36

to EPA demonstrating an 18% reduction from 2002-2008 for the Sacramento 

nonattainment area with existing control strategies. In addition, the 2006 RFP plan 

included an updated emissions inventory and set new motor vehicle emission budgets 

for 2008, which EPA found to be adequate for transportation conformity purposes37.

The Sacramento region was required to submit a plan demonstrating RFP through 

2011. The 2011 RFP was due to EPA on June 15, 2007. EPA made a finding of failure 

to submit the 2011 RFP SIP and began federal sanctions clocks for the Sacramento 

region, effective March 24, 200838.

In May 2008, an 8-hour ozone 2011 RFP plan39 approved by the air districts in the 

Sacramento nonattainment area was submitted to CARB. This RFP plan demonstrated 

a 27% reduction from 2002-2011 for the Sacramento nonattainment area with existing 

control strategies. In addition, the 2011 RFP plan included an updated emissions 

inventory and carried forward 2008 motor vehicle emission budgets to 2011 for 

transportation conformity purposes.

The preparation and approval of the 2011 RFP plan was expedited to stop the sanctions 

clocks. Because of the expeditious schedule, the 2011 RFP was prepared before final 

approval of SACOG’s recent Metropolitan Transportation Plan for 2035, which 

contained updated motor vehicle activity. Therefore, this Sacramento Regional 8-Hour 

Ozone Attainment and RFP Plan incorporates the transportation activity data from the 

final MTP2035 and replaces the emissions inventory and motor vehicle emission 

budgets in the previous 2011 RFP submittal.

 

36 Sacramento Regional Nonattainment Area 8-Hour Ozone Rate-of-Progress Plan (February 2006).

37 Federal Register, March 14, 2006, p. 13124 (effective date March 29, 2006).

38 “Finding of Failure to Submit State Implementation Plans Required for the 1997 8-Hour Ozone NAAQS” 

(Federal Register, March 24, 2008, p.15416-15421.

39 Sacramento Regional 8-Hour Ozone 2011 Reasonable Further Progress Plan (May 2008).
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As a result of the Sacramento nonattainment area’s reclassification to severe, RFP 

milestone years also include 2014, 2017, and 2018. Therefore, this ozone plan includes 

RFP demonstrations for each of these years to satisfy the RFP submittal requirements. 
8-Hour Ozone Air Quality Trends 

Page 3-7 

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4 8-HOUR OZONE AIR QUALITY TRENDS

4.1 Introduction to Air Quality Trends

The progress toward attainment is measured by analyzing ambient air quality data 

collected at various monitoring sites over a period of many years. This chapter focuses

on two different 8-hour ozone parameters: the number of days exceeding the 8-hour 

ozone standard and the magnitude of the 8-hour ozone design value concentrations. 

Additional information regarding trend analyses can be found in Chapter 10 and 

Appendix E – Weight-of-Evidence Analyses.

4.2 Ozone Monitoring Sites

There are currently 16 ozone monitoring stations located throughout the Sacramento 

nonattainment area that are operated by either local air districts or the California Air 

Resources Board. In 2010, one monitoring site was relocated from the Sacramento 

Airport Road site to Goldenland Court. Most ozone sites also have meteorological 

instruments, and some sites sample for ambient concentrations of ozone precursor 

pollutants.

See Figure 4-1 for a map showing the location of each of the ozone monitoring stations 

operating in the Sacramento region during 2012.

4.3 Annual Number of Exceedance Days

Table 4-1 shows the annual number of days over the 8-hour ozone standard for each of 

the ozone monitoring sites in the Sacramento nonattainment area since 1990. The most 

frequent exceedances of the federal 8-hour ozone standard occur at the region’s 

eastern monitoring sites (Cool, Folsom, Placerville, and Auburn). The number of 

exceedance days at the peak monitoring site varies year to year, between 8 and 42. 

The bar chart in Figure 4-2 illustrates the monitoring site locations that exceeded the 

federal 8-hour ozone standard the most days in each year. Year to year ozone 

differences are caused by meteorological variability and changes in precursor emission 

patterns. The 8-hour ozone standard allows for up to 3 exceedance days per site per

year since the fourth-highest daily maximum 8-hour ozone concentration is used to 

calculate the ozone design value.

4.4 Trend in Exceedance Days

The line graph in Figure 4-3 shows the number of exceedance days for the peak 

monitoring site in each year and a trend line from 1990 to 2012. The 23-year trend line 

indicates a decline in the overall average peak number of annual exceedance days, 

from about 34 down to 15, which equals a decline rate of about 0.8 exceedance days

per year.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

8-Hour Ozone Air Quality Trends

Page 4-2

The historical ambient air quality data (Tables 4-1) show that Cool and Folsom were 

the sites recording the highest number of exceedance days in the past 23 years. In the 

previous Plan revisions, Cool was the peak exceedance site from 1996 -2007. During 

this 12 year period, Cool has recorded the highest number of exceedance days for 8 

years. In the recent five year period (2008 – 2012), the Folsom monitor has recorded 

the highest number of exceedance days and peak design values.

4.5 Ozone Design Values

Table 4-2 lists the 8-hour ozone design value concentrations for each of the ozone 

monitoring sites in the Sacramento nonattainment area since 1990. To show attainment, 

the ozone design value must meet the 8-hour ozone standard (84 ppb). A monitoring 

site’s 8-hour ozone design value is calculated by averaging the annual fourth-highest 

daily maximum 8-hour average ozone concentrations over the most recent three 

years40. The location of the highest 8-hour ozone design value concentrations occurs 

most frequently at the region’s eastern monitoring sites (Cool, Folsom, Placerville, 

Auburn, and Colfax). The region’s peak ozone design value concentration varies from 

year to year, between 95 ppb and 110 ppb. Folsom was the peak design value site for 

the past 7 years.

4.6 Trend in Ozone Design Value

The line graph in Figure 4-4 shows the ozone design value for the peak monitoring site 

in each year and a trend line from 1990 to 2012. The overall 23-year trend line indicates 

a decline, from 107 ppb down to about 98 ppb. The ozone design value has improved 

from being 24 ppb (or 28%) over the standard41 down to about 14 ppb (or 16%), which 

equals a decline rate of about 0.4 ppb per year.

 

40 For example, the 2007 ozone design value concentration for a specific monitoring site would be 

calculated by taking the average of:

2005 4th highest daily maximum 8-hour average ozone concentration

2006 4th highest daily maximum 8-hour average ozone concentration

2007 4th highest daily maximum 8-hour average ozone concentration

41 Federal 8-hour ozone standard = 84 ppb.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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8-Hour Ozone Air Quality Trends

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Figure 4-1

Sacramento Nonattainment Area

Ozone Monitoring Stations

2012 Ozone Monitoring Sites (County)

Sacramento Nonattainment Area Sites

1. Auburn (Placer Co.) 11. Sacramento – Goldenland Court. 

(Sac. Co.)

2. Colfax (Placer Co.) 12. Sacramento – Del Paso Manor (Sac. 

Co.)

3. Cool (El Dorado Co.) 13. Sacramento – T Street (Sac. Co.)

4. Davis (Yolo Co.) 14. Sloughhouse (Sac. Co.)

5. Echo Summit (El Dorado Co.) 15. Vacaville (Solano Co.)

6. Elk Grove (Sac. Co.) 16. Woodland (Yolo Co.)

7. Folsom (Sac. Co.)

8. North Highlands (Sac. Co.) Other Sites

9. Placerville (El Dorado Co.) 17. Grass Valley* (Nevada Co.)

10. Roseville (Placer Co.) 18. Jackson** (Amador Co.)

*Grass Valley site: 2007 ozone design value = 95 ppb, and modeling analysis is applied for 2018.

**Jackson site informational only: 2007 ozone design value = 81 ppb, and modeling analysis is not applied.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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8-Hour Ozone Air Quality Trends

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Table 4-1

8-Hour Ozone Exceedance Days

Sacramento Nonattainment Area – Ozone Monitoring Sites

Monitoring Site 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Auburn 41 25 26 15 25 18 17 1 16 25 17 21 15 11 12 10 29 0 13 3 3 3 na

Colfax 12 4 12 11 5 2 8 9 0 2 18 12 9 13 14 1 3 0 0 1 1

Cool 30 10 25 35 29 32 42 22 8 22 30 10 15 6 1 8 1

Davis 3 0 4 1 0 2 4 1 4 5 2 2 2 0 0 0 1 1 1 0 0 0 0

Echo Summit 0 0 0 0 0 0 0 0 0 0 0 0 0

Elk Grove 0 3 4 9 3 4 7 1 3 0 5 1 2 7 1 2 1 1 0 1

Folsom 1 40 30 13 22 27 23 8 26 18 15 19 23 26 7 19 25 7 25 22 8 14 12

North Highlands 4 5 5 3 6 11 15 0 9 5 7 7 11 4 1 2 10 1 0 1 2 1 1

Placerville 29 12 22 31 27 13 17 23 15 15 20 19 7 16 20 4 16 5 2 1 6

Pleasant Grove* 0 0 4 2 0 7 5 0 4 3 3 3 2

Rocklin* 12 24 9 19 17 20 4 12 11 12 8 15

Roseville 7 8 8 12 2 12 9 8 9 11 5 1 9 9 3 13 11 5 3 5

Sac-Airport Rd.** 6 1 1 2 0 1 0 1 1 1 2

Sac-Del Paso M. 17 14 14 6 5 23 13 1 10 6 9 6 23 13 3 10 10 2 7 8 1 1 3

Sac-Goldenland 

Court 0 0 0 0 0

Sac-T Street 2 2 2 1 0 3 3 1 4 4 0 3 3 1 0 1 3 1 2 1 0 1 1

Sloughhouse 3 24 19 18 15 16 19 8 10 17 2 10 7 4 4 7

Vacaville 1 na na na na 3 2 0 7 8 0 0 0 0 1 0 2 0 1 1 0 0 0

Woodland 2 1 6 1 0 3 2 0 4 4 0 1 4 0 0 2 4 0 1 0 0 0 0

Peak Site 41 40 30 15 25 31 30 13 26 35 29 32 42 26 12 22 30 10 25 22 8 14 12

Data source: CARB air quality data base (www.arb.ca.gov/adam/welcome.html). Downloaded on 06/06/02013.

*Site closed

** Sac-Airport Road site was relocated to Sac-Goldenland Court in 2010.

na = insufficient data available
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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8-Hour Ozone Air Quality Trends

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Figure 4-2

8-Hour Ozone Exceedance Days

Sacramento Nonattainment Area – Peak Monitoring Site

Federal 8-hr ozone standard = 84 ppb

0

5

10

15

20

25

30

35

40

45

50

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Days Exceeding

Year

Auburn - Placer County Cool - El Dorado County

Folsom - Sacramento County Placerville - El Dorado County
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8-Hour Ozone Air Quality Trends

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Figure 4-3

8-Hour Ozone Exceedance Days Trend

Sacramento Nonattainment Area – Peak Monitoring Site

y = -0.8478x + 34.957

R2 = 0.3188

0

5

10

15

20

25

30

35

40

45

50

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Days Exceeding

Year

8-Hour Ozone Exceedance Days

Sacramento Nonattainment Area - Peak Monitoring Site

1997 federal 8-hour ozone standard = 84 ppb

This trend analysis uses the highest number of 8-hour ozone exceedance days above the 1997 federal 8-hour ozone standard recorded each year at the various 

monitoring sites, including the addition of the Cool station in 1996.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

8-Hour Ozone Air Quality Trends

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Table 4-2

8-Hour Ozone Design Values (ppb)

Sacramento Nonattainment Area – Ozone Monitoring Sites

Monitoring Site 1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Auburn 107 105 105 101 102 105 103 95 95 97 102 101 101 99 95 92 93 89 90 86 87 80 na

Colfax na na 92 92 91 86 86 86 79 73 77 88 92 91 97 94 89 79 78 74 75

Cool na na 103 103 107 104 106 107 102 97 95 96 98 93 89 84 83

Davis 78 73 80 78 79 78 82 79 80 81 85 81 77 76 74 73 74 75 76 74 72 70 70

Echo Summit 75 76 75 72 72 73 76 74 71 67 69

Elk Grove 81 87 87 87 88 85 84 75 80 77 82 82 83 82 79 77 74 74

Folsom 101 100 101 110 104 106 106 na 92 101 104 99 100 100 97 97 97 98 102 100 102 95 95

North Highlands 87 82 88 87 87 88 91 88 89 87 89 89 92 91 85 80 82 80 78 74 75 77 77

Placerville na na 97 99 103 99 98 98 99 96 94 95 94 94 94 93 96 92 90 80 81

Pleasant Grove* 82 76 79 82 81 82 83 82 81 81 84 83 82

Rocklin* na na 101 103 100 100 95 94 92 93 91 92

Roseville na na 97 96 93 93 89 93 90 92 90 87 86 89 89 90 89 90 86 85

Sac-Airport Rd.** na na 82 79 78 77 74 73 73 76 78

Sac-Del Paso M. 96 95 100 99 92 96 100 97 95 91 95 92 95 97 95 92 90 90 87 86 85 81 78

Sac-Goldenland 

Court 57 69 69

Sac-T Street 76 79 79 78 78 80 77 79 80 82 80 79 79 75 73 76 78 79 77 75 71 71

Sloughhouse na 100 105 98 95 95 94 94 96 93 95 91 92 87 88

Vacaville 75 na na na na na na 76 82 85 85 77 72 68 na 71 73 74 75 72 71 68 69

Woodland 80 77 na na 79 78 81 79 na na 84 82 83 83 79 77 79 80 79 74 72 69 69

Peak Site 107 105 105 110 104 106 106 101 103 103 107 104 106 107 102 97 97 98 102 100 102 95 95

Data source: CARB air quality data base (www.arb.ca.gov/adam/welcome.html) Downloaded on 06/06/02013.

*Site closed after 2002.

** Sac-Airport Road site was relocated to Sac-Goldenland Court in 2010.

na = insufficient data available
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

8-Hour Ozone Air Quality Trends

Page 4-8

Figure 4-4

8-Hour Ozone Design Values Trend

Sacramento Nonattainment Area – Peak Monitoring Site

This trend analysis uses the highest 8-hour ozone design values based on ozone concentrations recorded each year at the air monitoring stations, including the addition of the Cool 

station in 1996.

y = -0.4447x + 107.94

R2 = 0.5218

84

88

92

96

100

104

108

112

116

1990 1991 1992 1993 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012

Ozone Concentration (ppb)

Federal 8-hr ozone standard = 84 ppb Year
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and Reasonable Further Progress Plan September 26, 2013

Emissions Inventory

Page 5-1

5 EMISSIONS INVENTORY

5.1 Introduction to Emissions Inventory

Planning efforts to evaluate and reduce ozone air pollution include identifying and 

quantifying the various processes and sources of VOC emissions (such as solvents, 

surface coatings, and motor vehicles) and NOX emissions (such as motor vehicles and 

other fuel combustion equipment). VOC pollutants are also known as reactive organic 

gases (ROG), and the two are considered to be synonymous for this report.

The summary of VOC and NOX emissions estimates by different air pollutant source 

categories are provided for the SIP planning years in tabular and graphical formats. This 

Plan reflects the impact from the recent economic recession and the improvements to 

the on-road motor vehicles and the off-road equipment emission estimates. The 2002 

base year, 2014, 2017 and 2018 emission inventories use the latest planning 

assumptions and emissions data in California Air Resources Board’s (CARB’s) 

California Emission Projection Analysis Model (CEPAM). These inventories, presented 

in tons per day for an average summer day, are forecasted using the latest socioeconomic growth indicators and applying the emission reduction benefits from adopted 

control strategies. Emission reduction credits are also included in the emissions 

inventory forecasts. More detailed information and emissions inventory tables are 

provided in Appendix A – Emissions Inventory.

5.2 Emission Inventory Requirements

Emissions are updated as part of the overall requirement for “plan revisions to include a 

comprehensive, accurate, current inventory of actual emissions from all sources of the 

relevant pollutants” under sections 172(c)(3) and 182(a)(1) of the Clean Air Act. The 

baseline year for the SIP planning emissions inventory is identified as 2002 by EPA 

guidance memorandum42.

Additional EPA emission inventory guidance43 and federal 8-hour ozone implementation 

rules44 set specific planning requirements pertaining to future milestone years for 

reporting reasonable further progress (RFP) and to attainment demonstration years. 

Key RFP analysis years in this report include 2014 and every subsequent 3 years out to

and including the attainment date.

The attainment date for a “severe” nonattainment area classification is June 15, 2019. 

However, in order to attain by June 15th, the prior year’s ozone season would need to 

 

42 “2002 Base Year Emission Inventory SIP Planning: 8-Hour Ozone, PM2.5 and Regional Haze 

Programs” (EPA Memorandum from L. Wegman and P. Tsirigotis, November 18, 2002).

43 “Emission Inventory Guidance for Implementation of Ozone and Particulate Matter National Ambient Air 

Quality Standards (NAAQS) and Regional Haze Regulations” (EPA-454/R-05-001, August 2005, updated 

November 2005).

44 “Final Rule to Implement the 8-Hour Ozone National Ambient Air Quality Standard – Phase 2” (Federal 

Register, November 29, 2005, p. 71612-71705).
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be in attainment.45 Therefore, the emission inventory year for attainment analysis 

purposes is 2018, the year preceding the mandated attainment date.

The emissions inventory years included in this plan are 2002 (baseline), 2014, 2017, 

and 2018. EPA emission inventory guidance46 also requires the SIP planning emissions 

inventory to be based on estimates of actual emissions for an average summer 

weekday, typical of the ozone season (May – October).

5.3 Emission Inventory Source Categories

Due to the large number and wide variety of emission processes and sources, a 

hierarchical system of emission inventory categories was developed for more efficient 

use of the data. The anthropogenic emissions inventory is divided into four broad 

categories: stationary sources, area-wide sources, on-road motor vehicles, and other 

mobile sources. Each of these major categories is subdivided into more descriptive 

subcategory sources. Each of these subcategories is further defined into more specific 

emission processes.

5.3.1 Stationary Sources

The stationary source category of the emissions inventory includes non-mobile, fixed 

sources of air pollution. They are mainly comprised of individual industrial, 

manufacturing, and commercial facilities called “point sources.” The more descriptive 

subcategories include fuel combustion (e.g., electric utilities), waste disposal (e.g., 

landfills), cleaning and surface coatings (e.g., printing), petroleum production and 

marketing, and industrial processes (e.g., chemical). Industrial facility operators 

reported the process and emissions data used to calculate emissions from point 

sources.

5.3.2 Area-Wide Sources

The area-wide sources inventory category includes aggregated emissions data from 

processes that are individually small and widespread or not well-defined point sources. 

The area-wide subcategories include solvent evaporation (e.g., consumer products and 

architectural coatings) and miscellaneous processes (e.g., residential fuel combustion 

and farming operations). Emissions from these sources are calculated from product 

sales, population, employment data, and other parameters for a wide range of activities

that generate air pollution across the Sacramento nonattainment region. More detailed 

information on the area-wide source category emissions can be found on the CARB 

website: http://www.arb.ca.gov/ei/areasrc/areameth.htm

 

45 “Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals 

for Ozone, PM2.5, and Regional Haze” (EPA, April 2007, p. 35).

46 “Emission Inventory Guidance for Implementation of Ozone and Particulate Matter National Ambient Air 

Quality Standards (NAAQS) and Regional Haze Regulations” (EPA-454/R-05-001, August 2005, updated 

November 2005, p. 17).
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5.3.3 On-Road Motor Vehicles

The on-road motor vehicles inventory category consists of trucks, automobiles, buses, 

and motorcycles. EMFAC (EMission FACtor) is California’s model for estimating 

emissions from on-road motor vehicles operating in California. It is built on decades of 

vehicle testing and analysis. It uses travel activity data from metropolitan planning 

organizations, vehicle registration data from the Department of Motor Vehicles (DMV), 

and data from the Smog Check program. EMFAC has undergone many revisions over 

the years and the current on-road motor vehicles emission model, EMFAC201147, is 

used in this Plan.

Motor Vehicle Emissions Model, EMFAC2011

The California Air Resources Board (CARB) has continued to update and improve its 

EMFAC on-road motor vehicle emissions model. CARB’s EMFAC2011 model was 

released in September 2011, and it replaces EMFAC2007. EMFAC2011 model 

improvements include:

 The latest information on vehicle populations and miles traveled in California.

 The impacts of recently adopted diesel regulations including the Truck and Bus 

Rule and other diesel truck fleet rules; the Pavley Clean Car Standard, and the 

Low Carbon Fuel Standard.

 The latest emissions inventory methods for heavy duty trucks and buses.

EMFAC2011 software and detailed information on the vehicle emission model can be 

found on the CARB website: http://www.arb.ca.gov/msei/modeling.htm.

Vehicle Activity Data

On-road motor vehicle emission estimates were developed using the latest available 

transportation data and California’s EMFAC2011 model. The forecasted vehicle miles 

traveled (VMT)48 and speed distributions used in this plan are based on transportation 

modeling for the Sacramento region’s Final 2013/2016 Metropolitan Transportation 

Improvement Program (2013/2016 MTIP)49, which was adopted by Sacramento Area 

Council of Governments (SACOG) on August 16, 2012, and approved by FHWA on 

December 14, 2012. All projects included in the MTIP must be consistent with the 

Metropolitan Transportation Plan/Sustainable Communities Strategy 2035 (MTP/SCS 

 

47 CARB conducted off model runs to incorporate 2013/2016 MTIP travel forecasts that were not included 

in the released EMFAC2011 model. (Jon Taylor e-mail providing 2014, 2017, 2018 on-road emissions 

based on October & November 2012 SACOG activity, formally transmitted to SMAQMD on December 5, 

2012).

48 SACOG travel data transmittal letter to CARB, and October 10, 2012 and November 30, 2012 e-mails 

to SMAQMD.

49 Final 2013/16 Metropolitan Transportation Improvement Program (MTIP), Amendment #1 to the 

MTP/SCS 2035, and Air Quality Conformity Analysis. (August 16, 2012), FHWA approval December 14, 

2012.
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2035) for the Sacramento Region. Final 2013/2016 MTIP is Amendment #1 to the 

MTP/SCS2035. Vehicle activity data for Solano County portion of the nonattainment 

area is based on Plan Bay Area Preferred Land Use Scenario/Transportation 

Investment Strategy (May 11, 2012) and was provided by San Francisco Bay Area 

Metropolitan Transportation Commission (MTC) to SACOG50.

5.3.4 Other Mobile Sources

The emission inventory category for other mobile sources includes aircraft, trains, ships, 

and off-road vehicles and equipment used for construction, farming, commercial, 

industrial, and recreational activities. Like EMFAC, the off-road emissions model 

underwent a significant update. The OFFROAD2007 model has been updated with

category-specific methods and inventory models. The diesel equipment categories 

using category specific method include: In-Use Off-Road Equipment (Construction, 

Industrial, Ground Support and Oil Drilling); Cargo Handling Equipment; In-Use Mobile 

Agricultural Equipment; Locomotives; Transport Refrigeration Units; Commercial Harbor 

Craft; Ocean Going Vessels; and Stationary Commercial Engines. The base 

OFFROAD2007 emission model also includes emission estimates of equipment 

categories which have not yet been replaced with a category specific method (e.g., lawn 

and garden equipment, farm equipment). In general, emissions are calculated by using 

estimated equipment population, engine size and load, usage activity, and emissions 

factors.

Off-road inventory improvements that have the greatest impact in the Sacramento 

region are described in a CARB report entitled “2010 Documentation (Appendix D)”. 

The most significant off-road inventory improvements include:

 Updated estimates of equipment population

 New data from 2009 academic studies and from engine manufacturers 

suggesting load factors be reduced by 33%

 Decreases in construction activity and revised projections of growth due to the 

recent economic recession.

More detailed information on the latest off-road motor vehicle emissions inventory, 

including “2010 Documentation (Appendix D)”, can be found on the CARB website: 

http://www.arb.ca.gov/msei/categories.htm#offroad_motor_vehicles.

5.3.5 Biogenic Sources

Biogenic emissions are emissions from natural sources, such as plants and trees. Using 

the BEIGIS model and region-specific input databases on vegetation land cover, 

species composition, leaf mass distribution, temperature and light conditions, CARB 

estimates emission of biogenic volatile organic compounds (BVOC) from vegetation for 

 

50 MTC (Harold Brazil) Eastern Solano travel data transmittal letter to SACOG, May, 2012, and October 

16, 2012 e-mail forwarded to SMAQMD.
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natural areas, agricultural crops, and urban landscapes. BVOC emissions vary with 

temperature.

Table 5-1 shows the sum of biogenic emissions for the Sacramento nonattainment area 

for six episodic days used in ozone modeling and for an average episodic day. More 

detailed information on the emissions from natural sources can be found on the CARB 

website: http://www.arb.ca.gov/ei/naturalsources.htm

Table 5-1

Biogenic Emissions

Biogenic 

Category

VOC a(tons per day) By Episodic Day Used in Ozone Modeling

Sacramento Nonattainment Area

7/28/2000 7/29/2000 7/30/2000 7/31/2000 8/1/2000 8/2/2000 Avg Day

Urban 55 60 64 75 72 72 66

Agricultural 33 36 38 45 44 43 40

Natural 383 409 418 494 465 481 442

Total 472 505 520 614 580 596 548

a

Source: CARB, sum of Sacramento Nonattainment Area biogenic gridded emissions for episodic days, July 28-August 2, 2000, 

used in ozone modeling.

5.4 Base Year Emissions Inventory

Anthropogenic Emissions Table by Source Category

The following tables (Tables 5-2 and 5-3) show the anthropogenic emissions inventory 

of VOC and NOX by source categories for the Sacramento nonattainment area. The 

Sacramento nonattainment area for the federal 8-hour ozone standard includes all of 

Sacramento and Yolo Counties, eastern portion of Solano County, Placer and El 

Dorado Counties excluding the Lake Tahoe Basin, and the southern portion of Sutter 

County51. The emissions inventory for ozone planning purposes represents emissions 

for a summer seasonal average day in units of tons per day52. Inventories, except for 

2014, 2017 and 2018 on-road vehicles, were generated using CEPAM: NORCAL 2012 

 

51 Southern Sutter County emissions include:

1) all point sources located in the area, 

2) 6% of the county total of area and aggregated point sources that are projected by population or 

construction/demolition activity, where, 6% is the percent of Sutter County population in the Sutter 

portion of the Sacramento nonattainment area,

3) 34% of the county total for emissions from agriculture and off-road equipment, where, 34% is the 

percent of Sutter County land area in the Sutter portion of the Sacramento nonattainment area,

4) 0% of the county total for emissions from oil and gas operations, landfills, and cogeneration 

categories.

52 Annual emissions are multiplied by a summer seasonal factor, TF = [sum of fractional monthly 

throughputs for the emission process during May through October] / 184 days in the summer ozone 

season.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment 

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Page 5-6 

SIP Baseline Emission Projections53. On-road vehicle emissions for 2014, 2017 and 

2018 in this plan were generated separately to reflect updated VMT activity forecasts in 

the SACOG 2013/2016 MTIP54

. The VOC emissions total is 147 tons per day in 2002. 

The NOX emissions total is 165 tons per day in 2002. 

 

53 CARB CEPAM website, http://www.arb.ca.gov/app/emsinv/2012pm25sip/norcal2012pm25sip/; CEPAM: 

NORCAL 2012 PM2.5 SIP Baseline Emission Projections, Section a1 – Emission Projections With 

External Adjustments. 

54 Final 2013/16 Metropolitan Transportation Improvement Program (MTIP), Amendment #1 to the 

MTP/SCS 2035, and Air Quality Conformity Analysis. (August 16, 2012). FHWA approved on December 

14, 2012. 
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Table 5-2

Emissions of VOCa(tons per day)

Sacramento Nonattainment Area

2002 2014 2017 2018

TOTAL EMISSIONS 147 104 99 98

STATIONARY 22 26 27 27

AREA-WIDE 32 30 30 31

ON-ROAD MOTOR VEHICLES 52 21 17 15

OTHER MOBILE SOURCES 41 28 25 24

STATIONARY 

Solvent/Coatings 7.6 8.7 9.0 9.2

Petroleum Production/Marketing 4.7 6.2 6.4 6.5

Industrial Process 3.5 4.0 4.4 4.5

Waste Composting 4.3 4.4 4.4 4.4

Other 1.5 2.6 2.5 2.5

AREA-WIDE

Consumer Products 14.8 12.6 13.0 13.2

Architectural Coatings 8.4 8.8 9.2 9.3

Pesticides 1.8 1.2 1.2 1.2

Livestock Waste 2.6 2.9 2.9 2.9

Ag Burn/Other Managed Burn 1.0 1.0 1.0 1.0

Other 3.9 3.2 3.2 3.2

ON-ROAD

Automobiles 22.9 6.4 4.4 3.8

Lt/Med Duty Trucks 19.9 8.8 7.3 6.8

Heavy Duty Gas Trucks 3.5 1.9 1.6 1.5

Heavy Duty Diesel Trucks 2.5 1.4 1.2 1.2

Motorcycles 2.4 2.0 2.0 2.0

Buses/Motor Homes 0.7 0.3 0.2 0.2

OTHER MOBILE

Recreational Boats 20.3 13.7 12.3 11.9

Equipment (Const/Ind/Farm) 7.0 3.2 2.7 2.5

Lawn & Garden Equipment 6.5 5.5 5.1 5.1

Fuel Storage and Handling 3.1 1.6 1.4 1.4

Off-Road Recreational Vehicles 2.4 2.5 2.5 2.5

Trains 0.6 0.4 0.4 0.3

Aircraft 0.5 0.7 0.6 0.6

Ocean Vessels & Harbor Craft 0.1 0.1 0.1 0.1

a

Source: (CARB, 2012), includes 4 tpd of VOC ERCs and inventory adjustments identified in Appendix A5, Tables 

A5-1 and A5-2.
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Page 5-8

Table 5-3

Emissions of NOX

a

(tons per day)

Sacramento Nonattainment Area

2002 2014 2017 2018

TOTAL EMISSIONS 165 90 78 74

STATIONARY 12 13 12 12

AREA-WIDE 3 3 3 3

ON-ROAD MOTOR VEHICLES 99 46 37 34

OTHER MOBILE SOURCES 50 28 27 25

STATIONARY

Fuel Combustion 7.6 9.8 9.8 9.8

Ag Irrigation Pumps 3.8 2.1 1.1 1.0

Industrial Process 0.8 0.8 0.9 0.9

AREA-WIDE

Residential Fuel Combustion 2.5 2.7 2.6 2.5

Ag Burn/Other Managed Burn 0.5 0.6 0.6 0.6

ON-ROAD

Heavy Duty Diesel Trucks 48.4 25.7 20.1 18.5

Lt/Med Duty Trucks 24.9 9.1 7.3 6.6

Automobiles 18.3 4.7 3.5 3.2

Heavy Duty Gas Trucks 3.1 3.0 2.8 2.7

Buses/Motor Homes 4.1 2.5 2.3 2.1

Motorcycles 0.3 0.5 0.5 0.6

OTHER MOBILE

Construction & Mining Equip 11.6 3.5 4.1 3.6

Trains 12.1 7.1 7.1 7.0

Farm Equipment 13.0 7.3 5.8 5.3

Marine Vessels 4.6 3.7 3.2 3.2

Commercial/Industrial Equipment 3.5 1.5 1.5 1.4

Aircraft 1.7 2.5 2.8 2.8

Oil Drilling/Workover 1.7 0.6 0.5 0.5

Other 1.7 1.1 1.0 1.0

Transportation Refrigeration Units 0.7 0.6 0.5 0.5

a

Source: (CARB, 2012), includes 3 tpd of NOX ERCs and inventory adjustments identified in Appendix A5, Tables 

A5-1 and A5-2.
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2002 Emissions Pie Charts

The following pie charts (Figures 5-1 to 5-2) show the 2002 VOC and NOX emission 

inventory categories as a percentage of the total inventory for the Sacramento 

nonattainment region. In 2002, the VOC inventory includes 35% on-road mobile 

sources, 28% other mobile sources, 22% area-wide sources, and 15% stationary 

sources.

The NOX inventory is mainly due to mobile source combustion emissions. In 2002, the 

NOX inventory includes 60% on-road mobile sources, 31% other mobile sources, 2% 

area-wide sources, and 7% stationary sources.
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Figure 5-1

Figure 5-2
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2002 Top 10 Emission Categories

Figures 5-3 and 5-4 contain bar charts that display the 2002 top 10 emission inventory 

categories for VOC and NOX, respectively. The largest source categories for VOC are 

automobiles, light-duty trucks, recreational boats, consumer products, and architectural 

coatings. The largest source categories for NOX are heavy-duty diesel trucks, off-road 

equipment, light-duty trucks, automobiles, farm equipment, and trains.

State and federal laws limit local air district authority to regulate certain emissions 

sources, notably motor vehicles, off-road engines, and consumer products. EPA retains 

almost exclusive regulatory authority for emissions from trains, aircraft, and ships. Local 

air districts do not have direct authority to regulate seven of the top ten VOC source 

categories, and nine of the top ten NOX source categories. The significant categories 

that air districts have regulatory authority include solvents and coatings, architectural 

coatings, petroleum marketing, and stationary fuel combustion.

Figure 5-3
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Emissions Inventory 

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Figure 5-4

60 

50 

40 

~ 0 

Vi 30 c: 

0 

1-

20 

10 

0 

48 

,....--

I--

1-

1-

1-

Top Ten Categories for NOx Planning Emissions 

Sacramento Nonattainment Region 

2002 

19 18 18 

- - 13 12 

~m 8 7 - - -

D D 5 4 D D 
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Emissions Contribution by Agency Responsibility

Figures 5-5 and 5-6 show pie charts that identify the VOC and NOX emissions 

contribution by primary agency responsibility (District, CARB, or EPA). In terms of 

emissions, local air districts have direct regulatory authority for only 25% of VOC 

emissions and 9% of NOX emissions in the Sacramento region. CARB has the most 

regulatory responsibility over emissions, 74% of VOC and 82% of NOX, due to their

authority over mobile source emissions.

Figure 5-5

VOC Emissions Contribution by Primary Agency Responsibility

Sacramento Nonattainment Region

Figure 5-6

NOX Emissions Contribution by Primary Agency Responsibility

Sacramento Nonattainment Region

District

25%

EPA

CARB 1%

74%

2002 VOC

Total VOC = 147 
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5.5 Emission Inventory Forecasts

The emission inventory forecasts take into account anticipated population and economic 

growth and emission benefits from the federal, state and local control measures. In 

order to forecast emissions for various future milestone and attainment analysis years, 

growth parameters and the post-2002 emission reduction effects of control measures55

received by CARB as of mid-2011 are applied to the 2005emissions inventory at the 

emission process level for stationary and area-wide sources. The various growth 

parameters include forecasts for population, housing, employment, energy demand, 

motor vehicle travel, and other industrial and commercial outputs. Off-road motor 

vehicle emissions are forecasted separately by off-road category specific models using 

growth rates that were based on category-specific economic indicators such as 

employment, expenditures and fuel use. Future on-road emissions are determined by 

EMFAC2011 model using VMT forecasts in SACOG’s 2013/2016 MTIP56 and MTC’s 

Plan Bay Area Preferred Land Use Scenario/Transportation Investment Strategy (May 

11, 2012) for Solano County portion of SFNA57. Figure 5-7 contains a graph showing 

population and VMT growth58 for the Sacramento region. Existing control strategies 

continue to reduce future VOC and NOX emissions from stationary and area sources, 

on-road motor vehicles, and some other mobile source categories (such as off-road 

equipment).

 

55 Recently adopted CARB measures that went into effect by January 2012 and some adopted district 

control measures that went into effect by mid-2011 were manually adjusted into emission projections. 

These inventory adjustments are identified in Appendix A5, Tables A5-1 and A5-2.

56 Final 2013/16 Metropolitan Transportation Improvement Program (MTIP), Amendment #1 to the 

MTP/SCS 2035, and Air Quality Conformity Analysis. (August 16, 2012), FHWA approval December 14, 

2012.

57 Joint MTC Planning/ABAG Administrative Committees, Plan Bay Area Preferred Land Use and 

Transportation Investment Strategy. Oakland, CA: Bay Area Metropolitan Transportation Commission. 

[May 2012.]

58 Population:

1. Data source: CARB CEPAM growth table.

2. Except Solano, CEPAM population growth rate is based on SACOG forecasts in the 2008 MTP 

adopted by SACOG Board of Directors 12/16/04. CEPAM population growth rate, which is used for 

stationary and area–wide source forecasts is higher than the population growth rate in the 

MTP/SCS 2035.

3. Solano County population is from DOF projection released May 2012.

4. El Dorado County and Placer County population data exclude the Tahoe Basin.

5. Sacramento Nonattainment Area fraction for South Sutter is estimated at 6% of Sutter County.

VMT:

1. 2014, 2017, 2018 VMT activities are from SACOG travel data transmittal letter to CARB, and 

October 10, 2012 and November 30, 2012 e-mails to SMAQMD.

2. 2002 VMT is EMFAC2011 2002 default VMT.
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Figure 5-7

Population Growth and VMT Forecast

Sacramento Nonattainment Area

Tables 5-2 and 5-3 include the anthropogenic emissions inventory forecasts of VOC 

and NOX by source categories for the Sacramento nonattainment area. Emissions are 

given for milestone RFP years of 2014, and 2017, and for the attainment demonstration 

analysis year of 2018.

The following bar charts (Figures 5-8 and 5-9) show the VOC and NOX emission 

inventory forecasts for stationary sources, area-wide sources, on-road motor vehicles, 

and other mobile sources for the Sacramento nonattainment region. Bar charts are 

given for the 2002 base year and compared to the milestone RFP years of 2014, and 

2017, and to the attainment demonstration analysis year of 2018. The VOC and NOX

emission forecasts show significant declines in mobile source emissions, despite 

increasing population, vehicle activity, and economic development.
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Figure 5-8

Figure 5-9

41

28 25 24

52

21 17 15

32

30

30 31

22

26 27 27

0

20

40

60

80

100

120

140

160

180

200

2002 2014 2017 2018

VOC Emissions (tons/day)

VOC Planning Inventory Forecasts

Sacramento Nonattainment Region

Stationary

Area-Wide

On-Road Motor

Vehicles

Other Mobile

Sources

147

98 104 99

50

28 27 25

99

46 37 34

3

3

3 3

12

13

12 12

0

20

40

60

80

100

120

140

160

180

200

2002 2014 2017 2018

NOx Emissions (tons/day)

NOx Planning Inventory Forecasts

Sacramento Nonattainment Region

Stationary

Area-Wide

On-Road Motor

Vehicles

Other Mobile

Sources

165

74

90

78
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5.6 Emission Reduction Credits Added to Emission Inventory Forecasts

Certain pollutant emission reductions due to equipment shutdown or voluntary control 

may be converted to emission reduction credits (ERCs) and registered with the air 

districts. These ERCs may then be used as “offsets” to compensate for an increase in 

emissions from a new or modified major emission source regulated by the air districts. 

In the SMAQMD, ERCs may also be used as an alternative to strict compliance with 

specified rules. Thus, if a permitted source cannot meet the applicable emission 

standard requirements, usually because it is technically infeasible or not cost effective, 

the source may lease or purchase ERCs to achieve the required reductions.

Since ERCs represent potential emissions, they need to be taken into account in the 

emission inventories. One method is to assume that the use of ERCs will already be 

included within the projected rate of stationary source growth in the emissions inventory. 

However, if the use of available ERCs exceeds anticipated emissions growth, future 

emissions could be underestimated. Therefore, to ensure that the use of ERCs will not 

be inconsistent with the future reasonable further progress and attainment goals, the 

amount of ERCs issued for reductions that occurred prior to the 2002 base year are 

added to the emission inventory forecasts.

Emission Reduction Credits

For this attainment plan, the amounts of unused banked ERCs of emissions reductions 

that occurred prior to the 2002 baseline year for the Sacramento nonattainment area 

are 2.6 tons per day of VOC and 1.4 tons per day of NOX. The quantity of these ERCs is 

listed for each air district in Appendix A. The ERCs consist of emissions reduced from 

stationary sources and military aircraft. Including these ERCs here simply maintains the 

validity of previously banked ERCs and other reductions.

Future Bankable Rice Burning Emission Reduction Credits

California legislation59 in 1991 (known as the Connelly bill) required rice farmers to 

phase down rice field burning on an annual basis, beginning in 1992. A burn cap of 

125,000 acres in the Sacramento Valley Air Basin was established, and growers with 

400 acres or less were granted the option to burn their entire acreage once every four 

years. Since the rice burning reductions were mandated by state law, they would 

ordinarily not be “surplus” and eligible for banking. However, the Connelly bill included a 

special provision declaring that the reductions qualified for banking if they met the State 

and local banking rules.

Some rice burning reductions have been banked as ERCs. Other pre-2002 reductions 

in rice burning may be banked in the future under an ERC rule60 currently in 

 

59 Connelly-Areias-Chandler Rice Straw Burning Reduction Act of 1991, section 41865 of California 

Health and Safety Code.

60 This rice burning ERC rule must be approved by EPA into the SIP for the rice ERCs to be used for 

compliance with federal air quality requirements.
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development. The total amounts of potential bankable rice burning ERCs for the 

Sacramento nonattainment area are estimated at 0.9 ton per day of VOC and 1.0 ton 

per day of NOX. The potential future bankable rice burning ERCs are listed for each air 

district in Appendix A.

Summary of Emission Reduction Credits

ERCs issued for reductions that occurred prior to the 2002 base year and potential 

future bankable rice burning ERCs are summarized for the Sacramento nonattainment 

area, rounded up to 4 tpd VOC and 3 tpd NOX ERCs, and added to the VOC and NOX

emission inventory forecasts in Tables 5-4 and 5-5. The ERCs are not included in the 

2002 base year inventory.

5.7 Emissions Inventory Documentation

More detailed documentation of the VOC and NOX emissions inventory is provided in 

Appendix A. This appendix contains the estimated 2002, 2014, 2017, and 2018 

emission inventories for each county and air basin combination in the Sacramento 

nonattainment area. A listing of the VOC and NOX emission reduction credits by 

individual air district is also included.

Emission inventories are constantly being updated to incorporate new and better 

information and methodologies. Many improvements, especially in the mobile source 

categories, and the addition of previously un-inventoried emission sources, have been 

made to the inventory. Detailed information on emission methodologies, changes, and 

forecasts can be found on CARB websites: http://www.arb.ca.gov/ei/ei.htm and 

http:/www.arb.ca.gov/msei/msei.htm.
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Table 5-4

VOC Emission Reduction Credits Added to the Emission Inventory Forecasts

Sacramento Nonattainment Area

Emissions in tons/day 2002 2014 2017 2018

Emission Reduction Credits --- 2.6 2.6 2.6

Future Bankable Rice Burning

Emission Reduction Credits --- 0.9 0.9 0.9

Total ERCs (rounded up) --- 4 4 4

Emission Inventory Forecasts61 147 100 95 94

Total 147 104 99 98

Table 5-5

NOX Emission Reduction Credits Added to the Emission Inventory Forecasts

Sacramento Nonattainment Area

Emissions in tons/day 2002 2014 2017 2018

Emission Reduction Credits --- 1.4 1.4 1.4

Future Bankable Rice Burning

Emission Reduction Credits --- 1.0 1.0 1.0

Total ERCs (rounded up) --- 3 3 3

Emission Inventory Forecasts62 165 87 75 71

Total 165 90 78 74

 

61 VOC Emissions summaries in Table 5-2 include ERCs. The emission inventory forecasts in Table 5-4 

are calculated by subtracting 4 tpd of VOC ERCs from total emission in Table 5-2.

62 NOX Emissions summaries in Table 5-3 include ERCs. The emission inventory forecasts in Table 5-5 

are calculated by subtracting 3 tpd of NOX ERCs from total emission in Table 5-3.
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6 AIR QUALITY MODELING ANALYSIS

6.1 Introduction to Air Quality Modeling

Ozone is a secondary pollutant produced by complex chemical reactions in the air 

involving ozone precursor pollutants of volatile organic compounds (VOC) and nitrogen 

oxides (NOX) in the presence of sunlight. Ozone formation is also affected by 

meteorological characteristics (e.g., temperature, wind, vertical mixing, and humidity) 

and land surface features (e.g., land use, surface roughness, albedo, and terrain).

Due to the large number of atmospheric interactions, varying physical factors, and vast 

spatial boundaries pertaining to ozone formation, the evaluation of air quality problems

to develop adequate emission reduction strategies is inherently difficult and resource 

intensive. Therefore, state-of-the-science computer modeling is used to simulate the 

formation of ozone through mathematical descriptions of atmospheric processes and 

photochemical reactions of pollutants over large regional air basins.

This chapter describes the updated air quality modeling and analysis performed by the 

California Air Resources Board (CARB) with the help and cooperation of the various air 

districts, contracted agencies and consultants. The methodology and application of the 

modeling results for determining the emission reduction targets needed for attainment of 

the 1997 8-hour ozone standard in the Sacramento region are provided. More detailed 

documentation of the air quality modeling and analysis of results are included in 

Appendix B – Photochemical Modeling.

6.2 Air Quality Modeling Methodology and Applications

To evaluate attainment of the 8-hour ozone standard, it is necessary to understand 

existing high ozone episodes and then predict future ozone concentrations under 

changing emission scenarios. Extensive air monitoring and emissions data are first 

collected or estimated for actual high ozone episodes to provide information for 

developing base case model simulations. An air quality modeling episode can then be 

run for different future year emissions scenarios to study how reducing VOC and NOX

emissions will decrease ozone concentrations. Emission reduction levels for meeting 

the ambient ozone standard can be quantified for a specified attainment year.

Ozone air quality modeling has other uses besides estimating attainment of the ambient 

standard. It can also be used to assess the magnitude and impact of pollutants being 

transported between air basins. Another useful application could be to determine 

potential unmonitored high ozone areas where future monitoring sites may be installed.

6.3 Air Quality Modeling Analysis Requirements

Under section 182(c)(2)(A) of the Clean Air Act, the attainment demonstration for 

“serious and higher” nonattainment areas must be based on photochemical grid 

modeling or any other EPA-approved analytical method determined to be at least as 
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effective. In addition, EPA provides recommended guidance63 on how to apply air

quality models to generate results for preparing 8-hour ozone attainment 

demonstrations. The guidance document lists the following nine steps for applying an 

air quality model:

1. Develop a conceptual description of the problem to be addressed.

2. Develop a modeling/analysis protocol.

3. Select an appropriate model to support the demonstration.

4. Select appropriate meteorological episode time periods to model.

5. Choose an appropriate area to model with appropriate horizontal/vertical resolution 

and establish suitable initial and boundary conditions.

6. Generate meteorological inputs to the air quality model.

7. Generate emissions inputs to the air quality model.

8. Evaluate the performance of the air quality model and perform diagnostic tests to 

improve the model, as necessary.

9. Perform future year modeling (including additional control strategies, if necessary) 

and apply the attainment test.

EPA’s modeling guidance document64 describes a modeled attainment test as an 

exercise in which an air quality model is used to simulate current and future air quality

for selected high ozone episodes. The estimated reduction in modeled future ozone is 

used in a relative rather than absolute sense to predict attainment. The simulated 

percent reduction in future ozone at each nonattainment monitor is applied to the 

monitor’s actual observed average baseline ozone design value. If the calculated future 

ozone design value concentrations are  84 ppb, then the attainment test is satisfied for 

the monitors.

The modeled attainment test should be applied at monitors within the nonattainment 

area. Because the State is responsible for analyzing downwind and upwind influences 

from or on other areas outside the nonattainment area, the recommended modeled 

attainment test predicts whether or not all estimated future design values will achieve

the ozone NAAQS under modeled meteorological conditions.

6.4 Central California Ozone Study

The Central California Ozone Study (CCOS) consisted of a field program, data analysis, 

emission inventory development, and modeling. Sponsors and participants in CCOS 

include federal, state, and local governmental agencies, university researchers, private 

consulting firms, industry associations, and environmental groups. The main goals of 

the CCOS activities and analyses were to enable CARB and central California air 

districts to further evaluate VOC and NOX control strategies, to determine the impacts of 

pollutant transport between air basins, and to provide the technical basis for preparing

 

63 “Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals 

for Ozone, PM2.5, and Regional Haze” (EPA, April 2007, p. 121-125).

64 Ibid., p.15 and 40-42.
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the attainment demonstration plans for the federal 8-hour ozone State Implementation 

Plan.

The CCOS field program was conducted during the summer of 2000 and included 

massive air quality and meteorological data collection over all of central California and 

most of northern California. Supplemental continuous surface and upper air monitoring 

equipment and more comprehensively instrumented research stations were specifically 

installed and operated to complement the existing routine air monitoring networks. Also, 

during forecasted high ozone episode days, additional sophisticated air measurements 

were taken using specially-equipped aircraft, speciated VOC surface samplers, and 

radiosonde upper air meteorological and ozone telemetry monitors.

6.5 Description of Air Quality Model and Modeling Inputs

The photochemical grid modeling used for the 8-hour ozone attainment analysis is 

developed with the CAMx65 air quality model. The CAMx model simulates a threedimensional atmosphere over multiple days, and is used to investigate air pollution at 

the spatial resolution of 4 km grid squares for the entire CCOS area (see modeling 

domain in Figure 6-1). It is computationally efficient, publicly available, and acceptable 

to EPA for SIP modeling. The CAMx model is run using the SAPRC-99 chemical 

mechanism66. The model calculates air quality concentrations averaged for each hour at 

each 4 km grid square location at the surface and for each vertical layer above.

Air quality models require time varying meteorological fields including winds, 

temperature, and water vapor content to calculate the transport and transformations of 

air pollutants. Meteorological inputs to the SIP air quality modeling project were

developed by NOAA and CARB using the widely employed Mesoscale Model version 5 

(MM5). The MM5 model is a prognostic meteorological model which is driven mainly by 

the principles of physics (e.g., laws of thermodynamics and conservation of mass)

instead of being strongly influenced by observed meteorological data. However, the 

MM5 model run is improved by using four dimensional data analysis (FDDA), which 

does allow some wind calculations to be adjusted by actual monitoring data.

The MM5 model is able to simulate mesoscale and regional-scale atmospheric 

circulation using its multiple-nest capability that allows sub-domains to be examined at 

finer spatial resolutions. The MM5 model was run using multiple sub-domains with 

resolutions of 36 km, 12km, and 4 km grid squares. Also, the vertical structure of the 

meteorological modeling incorporated a 30-50 layer configuration.

Air quality models also require inputs for time varying and spatially gridded emissions 

estimates. The modeling emissions files consist of hourly speciated emissions for 

elevated point, area, motor vehicle, and biogenic sources for each grid cell, which are 

provided by various methods. Point and area source emissions are processed into 

 

65 CAMx is Comprehensive Air Quality Model with extension, version 4.03a (as modified by CARB).

66 Chemical mechanism originally developed by the Statewide Air Pollution Research Center (SAPRC) of 

the University of California at Riverside.
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modeling inputs using the CARB-developed Emissions Modeling System (EMS-95). Onroad motor vehicle emissions are gridded using Caltrans’ Direct Travel Impact Model 

(DTIM). Emissions from biogenic sources are generated for modeling by CARB’s 

BEIGIS program.

Other air quality model inputs include estimates of speciated concentrations for initial 

and boundary conditions. Initial pollutant concentrations represent ambient air quality 

inside the modeling domain at the time the modeling episode begins. Boundary 

conditions represent pollutant concentrations entering the modeling domain from the 

vertical top and horizontal side borders.
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Figure 6-1

Photochemical Modeling Domain

Central California Ozone Study

185x185 Grid Cells at 4x4-km Horizontal Resolution

6.6 Selection and Characterization of Modeling Episodes

Two high ozone episodes were selected for air quality modeling and analysis in this 

plan. One of the episodes occurred during the summer 2000 field data collection of the 

Central California Ozone Study. The summer 2000 ozone modeling episode includes 5 

days from July 29 to August 2. The start of this episode was characterized by a typical 

high pressure system centered over the Four Corners area (Utah, Arizona, Colorado, 

and New Mexico). The relatively large high pressure ridge slowly migrated west and 

became centered near Reno, Nevada by July 31, creating meteorological conditions 

conducive to high ozone formation in Central California.

The other episode took place in July 1999 under more routine air monitoring data 

collection. The July 1999 ozone modeling episode includes 5 days from July 9 to 13.

This episode is characterized by a much broader high pressure system than the 

summer 2000 episode. The high pressure system encompassed the Four Corners area, 

the Pacific Northwest region, and the Eastern Pacific Ocean, causing meteorological 

conditions conducive to high ozone formation in Central and Northern California.
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Additional details of the meteorological and air quality characterization of the two 

modeling episodes are provided in Appendix B – Photochemical Modeling.

6.7 Base Case Model Performance Evaluation

After preparing the air quality modeling input files (e.g., meteorological fields, gridded 

emissions, initial and boundary conditions), the CAMx air quality model was run for the 

two different high ozone episodes. The July 29-August 2, 2000 and July 9-13, 1999

episodes also included two spin-up days prior to the beginning of each episode. Due to 

varying uncertainties and conditions in running air quality models, the model 

performance was evaluated for each base case scenario.

EPA modeling guidance67 recommends the operational evaluation should compare 

hourly ozone observations and predictions as well as 8-hour daily maximum

observations and predictions over the episode days (excluding spin-up days). The 

ozone data should be evaluated for all data pairs in which the observed concentrations 

are above 60 ppb, and for all data pairs without any minimum threshold. At a minimum, 

statistical calculations should be performed for: 1) mean normalized bias (MNB), 2) 

mean normalized gross error (MNGE), and 3) average peak prediction bias and error.

The summary statistics should be calculated for individual days averaged over all sites 

and for individual sites averaged over all days, and then aggregated into meaningful 

subregions or subperiods.

EPA modeling guidance does not assign an acceptance criteria level that distinguishes 

between adequate and inadequate model performance. Instead, EPA recommends that 

a qualitative weight-of-evidence approach consisting of a variety of performance tests 

be used to determine whether a particular modeling application is valid for assessing 

the future attainment status of an area.

Based on the statistical comparisons between observed and predicted ozone data, the 

base case modeling scenarios were determined to be performing adequately overall in 

the Sacramento region. Various summary base case model performance statistics

tables, additional base case model performance evaluations, and modeling 

documentation are provided in Appendix B – Photochemical Modeling.

6.8 Baseline and Future Year Model Runs for Each Episode

After the photochemical modeling base case episodes were shown to perform 

adequately, the modeling was run with the summer planning inventory for a 2002 

baseline year and a 2018 future year with existing control strategies for assessing

attainment of the ozone NAAQS. The EPA 8-hour ozone implementation rule (40 CFR 

51.908) states that emission reductions needed for attainment must be implemented by 

 

67 “Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals 

for Ozone, PM2.5, and Regional Haze” (EPA, April 2007, p. 190-198).
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the beginning of the ozone season immediately preceding the area’s attainment 

deadline date. Since the ozone season typically occurs May through October, the 

forecast model year for attainment demonstration analysis needs to represent the year 

preceding the June 15, 2019 attainment deadline date for a “severe” nonattainment 

classification.

6.9 Emission Reduction Credits Added to Future Year Model Runs

Emission reduction credits (ERCs) for the Sacramento region were discussed and 

quantified in Section 5.6. Since ERCs are potential future emissions, it is not currently 

known as to what emission sources they will be applied to and where the emission 

sources will be specifically located. Existing inventories for stationary emissions are 

gridded for modeling by using the point source facility locations. Estimated area-wide 

emissions are gridded for modeling using related spatial surrogate parameters, such as 

population and land use types.

Due to the uncertainty of the type and location of future sources using ERCs, the 

baseline VOC and NOX ERCs (including rice burning) for the Sacramento 

nonattainment area were spatially distributed to the future year gridded modeling 

inventory by increasing the existing stationary and area-wide emissions in Sacramento 

and Yolo Counties. This across-the-board percentage increase was only applied to 

Sacramento and Yolo Counties, because other counties in the Sacramento 

nonattainment area partially extend outside the nonattainment area.

6.10 Forecasted Ozone Design Values

The results from baseline and future year modeling runs are applied to each ozone 

nonattainment monitor to determine the predicted future ozone design value with the 

estimated future emissions scenario. The method for calculating the predicted future 

ozone design values is described by the following equation68:

DVfuture = RRF x (DVbase - BG) + BG where,

DVfuture = the estimated future design value concentration at the monitor used to 

predict attainment of the 8-hour ozone NAAQS ( 84 ppb). [Truncated to 

whole ppb]

RRF = the relative reduction factor which is the ratio of the future year (FY) modeled 

average 8-hour daily maximum ozone (rounded to tenths of a ppb) to the 

base year (BY) modeled average 8-hour daily maximum ozone (rounded to 

tenths of a ppb) for the monitor. [Rounded to three significant figures to right 

of decimal]

 

68 “Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals 

for Ozone, PM2.5, and Regional Haze” (EPA, April 2007, p. 20), and modified by ARB with consideration 

of background ozone.
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AVG

AVG

(BY BG)

(FY BG) RRF







BG = background ozone which is assumed at 40 ppb.

DVbase = the actual observed average base year design value concentration (2002-

2004) at the monitor for 8-hour ozone. [Rounded to tenths of a ppb]

A background ozone concentration is considered in the equations for calculating future 

ozone design value and relative reduction factor, because it is assumed that this 

represents the portion of a site’s ozone problem that cannot be mitigated by 

anthropogenic emission controls.

The results for the forecasted ozone design values for the future year 2018 are shown 

in Table 6-1. This future year corresponds to the attainment demonstration analysis 

year for a severe nonattainment classification. Any monitors with predicted future ozone 

design values greater than 84 ppb (in bold) are not expected to attain the 8-hour ozone 

NAAQS and indicate the need for additional VOC and/or NOX emission reductions in the 

Sacramento region.

Based on the photochemical modeling results, attainment was predicted at all ozone 

monitors in 2018, except for two sites (Cool and Folsom) located in the eastern part of 

the Sacramento nonattainment area. Therefore, additional modeling runs were 

conducted to estimate the emission reductions needed to demonstrate attainment of the 

8-hour ozone NAAQS for the 2018 forecast year.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Air Quality Modeling Analysis

Page 6-9

Table 6-1

Forecasted 8-Hour Ozone Design Values

2018 Attainment Analysis Year for Severe Classification

Sacramento Nonattainment Area

[A]

Baseline 

Design 

Valuea

(ppb)

[B]

Modeled 

Baseline 

Ozone 

(ppb)

[C]

Modeled 

Future 

Ozone 

(ppb)

[D]

Relative 

Reduction 

Factorb

[E]

Future 

Design 

Valuec

(ppb)

Auburn (Placer Co.) 98.3 104.8 88.3 0.745 83

Colfax (Placer Co.) 90.0 91.5 75.5 0.689 74

Cool (El Dorado Co.) 105.0 98.5 83.5 0.744 88

Folsom (Sac. Co.) 99.0 107.9 92.0 0.766 85

North Highlands (Sac. Co.) 89.3 101.4 89.8 0.811 79

Placerville (El Dorado Co.) 94.3 99.4 84.0 0.741 80

Roseville (Placer Co.) 89.7 103.4 89.1 0.775 78

Sac-Del Paso Manor (Sac. Co.) 95.7 106.6 93.6 0.805 84

Sloughhouse (Sac. Co.) 94.7 103.0 91.0 0.810 84

Adjacent Downwind Areas

Grass Valley (Nevada Co.) 97.7 95.0 81.0 0.745 83

a

Based on average of ozone design values for 2002, 2003 and 2004, except Colfax had insufficient data for 2002.

b

RRF calculation = (C – 40) / (B – 40)

c

Future design value calculation = RRF x (A – 40) + 40 [truncated to whole ppb]

The forecasted 8-hour ozone design values indicate that all of the high ozone monitoring sites in 

the Sacramento nonattainment area, except for Cool and Folsom, are predicted to attain the 

federal 8-hour ozone standard (84ppb) by 2018 without new control strategies. The Cool and 

Folsom monitoring sites are forecasted to remain above the standard and will need additional 

emission reductions to attain.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Air Quality Modeling Analysis

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6.11 Analysis of VOC and NOX Emission Reduction Strategies

The attainment plan must show that emissions in the Sacramento nonattainment area

will be reduced sufficiently to meet the federal 8-hour ozone air quality standard. The 

plan must identify emission reduction levels that provide for attainment of the standard, 

and show how the targets will be reached. Emission reduction targets are defined for 

both ozone precursor pollutants, VOC and NOX.

Ozone/Emission Reduction Graphs

Systematic reductions in anthropogenic VOC and/or NOX emissions were simulated to 

characterize the change in the resulting ozone concentrations. For each individual 

modeling run, domain-wide emissions for NOX-only, VOC-only, or both VOC and NOX

are scaled by factors ranging from 100% to 80% in increments of 5%. As a result, 

forecasted ozone concentrations were determined for 25 different combinations of 

varying VOC and/or NOX emission reductions. For example, one modeling run scaled

VOC emissions by 95% and NOX emissions by 85%, and then another run scaled VOC

emissions by 85% and NOX emissions by 95%.

The forecasted ozone concentration data (in ppb) associated with each of the 25

emission reduction modeling scenarios were used to ratio the future ozone design 

values, which were plotted on a graph for an individual monitoring site. These diagrams 

show the pattern of ozone responses to varying combinations in VOC and NOX

emission reductions. This exercise was performed for the 2018 attainment 

demonstration year, and evaluated at each of the nonattainment air monitoring sites.

The graph for the peak ozone design value site in the Sacramento region will generally 

determine the extent of additional emission reductions needed for attainment. Also, the 

particular VOC and NOX emission reductions associated with the region’s new control 

measures can be applied to the peak site’s diagram to estimate a future ozone design 

value concentration. The individual ozone/emission reduction graphs for the 

nonattainment ozone sites in the Sacramento region are shown in Appendix B –

Photochemical Modeling.

Air Quality Modeling Analysis Conclusions

Some general conclusions can be drawn based on the 2018 modeling results of 

forecasted emissions and the additional across-the-board percent emission reduction 

scenarios. The air quality modeling analysis shows that attainment can be reached by 

2018 with different combinations of VOC and NOX control. The modeling results indicate 

that both VOC and NOX reductions provide ozone benefits in the Sacramento region, 

but on a ton for ton basis NOX reductions provide greater ozone benefits than VOC 

reductions. More specific conclusions regarding attainment targets for the Sacramento 

region’s peak ozone monitoring site at Cool are provided in Chapter 8 – Attainment 

Demonstration.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Air Quality Modeling Analysis

Page 6-11

6.12 Air Quality Modeling Uncertainties

EPA’s modeling guidance document69 explains that, “Uncertainty is the notion that 

model estimates will not perfectly predict observed air quality at any given location, 

neither at the present time nor in the future.” Uncertainty arises for a variety of reasons.

For example, limitations in the model’s formulation may be due to an incomplete 

representation in the model of atmospheric physical and chemical processes. Modeling 

inaccuracies can also result from meteorological, emissions, and other input data base 

limitations, and uncertainty in forecasting future levels of emissions and changing land 

use.

Other factors adding to air quality modeling uncertainties include: 1) how well the 

meteorological episodes simulated in the modeling represent the severity of future 

meteorological conditions conducive to high ozone formation, 2) how well the 

methodology for forecasting ozone design values (by applying the relative reduction 

modeling results to baseline ozone design value concentrations) corresponds to actual 

future monitored ozone design values, and 3) how well domain-wide (especially Bay 

Area) emission reductions in the Sacramento attainment analysis are achieved, 

especially during those Sacramento ozone episodes when Bay Area transport is

significant.

The impact of future climate change is not included in the photochemical modeling 

assumptions. In the view of CARB modeling experts, the temperature changes during 

the timeframe of this SIP will likely be small enough to have very little impact on the 

model results. Effects of climate change would be speculative in the short term, and 

impacts on the region’s ability to attain will be tracked through the RFP process.

However, long term effects of climate change on future ozone concentrations are being 

evaluated. CARB staff reported70 that projected ozone response to climate change in 

2050 is estimated to cause a four percent increase in ozone relative to current 

meteorological conditions in the Sacramento region.

In order to mitigate potential air quality modeling uncertainties, the modeling guidance 

suggests using corroborative methods and analyses to support the air quality modeling 

results and attainment control strategy. This supplemental weight-of-evidence approach 

is discussed in Chapter 10.

 

69 “Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals 

for Ozone, PM2.5, and Regional Haze” (EPA, April 2007, p. 3) .

70 Report to the Board on Impacts of Climate Change on California: Scenarios Assessment Findings of 

the Climate Action Team, November 20, 2008. Staff presentation slide 15, which references Steiner et al., 

“Influence of future climate and emissions on regional air quality in California”, JGR (2006).
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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Proposed Control Measures

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7 PROPOSED CONTROL MEASURES

7.1 Introduction to Control Measures

The air quality modeling analysis performed by the California Air Resources Board 

(described in Chapter 6) shows that the Sacramento region will not attain the 1997 

federal 8-hour ozone standards by the mandated attainment deadline71 unless 

additional emission reductions are achieved. In addition, all reasonably available control 

measures are required. The proposed control strategy in this chapter will describe

measures and emission reductions to meet these requirements. This section uses the 

current projected inventory data and projected control measure reductions based on 

that current inventory. In addition, a contingency control measure strategy is defined.

More detailed information on the regional and local proposed new control measures is

provided in Appendix C – Proposed Control Measures (separate document) and 

Appendix D – Transportation Control Measures.

The Sacramento SIP control strategy relies on the following components:

1. Reductions from existing control measures and adopted rules,

2. Reductions from new state and federal regulations, and

3. Reductions from defined new SIP local and regional measures.

The proposed SIP emissions control strategy includes reductions of both VOC and NOX

air pollutants. A single NOX pollutant strategy is not appropriate because, even though 

VOC measures are not as effective as NOX, they still provide needed reductions. 

Moreover, many existing statewide and local control programs will inherently achieve 

reductions from both ozone precursors.

7.2 Reductions from Existing Controls

Air districts have been regulating stationary air pollution sources since the 1970’s.

Existing rules and their emission benefits are helping to make progress toward 

achieving air attainment goals. The benefits from existing rules are reflected in the 2018 

forecast inventory.

A coarse analysis was conducted to illustrate benefits from existing air district rules.

Figures 7-1 and 7-2 illustrate the amount of 2008 emission reduction benefits that are 

attributable to district stationary and area-wide source VOC and NOX rules since 1975.

Existing district rules resulted in reductions of roughly 60 tons per day of VOC and 20 

tons per day of NOX emissions. The most beneficial VOC rules are those affecting: 1) 

gasoline dispensing facilities and bulk terminals, and 2) solvent cleaning, degreasing, 

and painting operations. NOX rules regulating gas turbines and internal combustion 

engines have achieved the most NOX emission reductions for stationary and area-wide

sources.

 

71 “Final Rule to Implement the 8-Hour Ozone National Ambient Air Quality Standard – Phase 1” (Federal 

Register, April 30, 2004, p. 23951-24000).
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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Figure 7-1

Figure 7-2

2008 Benefits From District VOC Rules Since 1975 - 60 TPD

Sacramento Nonattainment Area

Reduction

60

2008

Inventory

 18

SOCMI, 2

Polyester Resin, 0.3

Bakeries, 0.4 Can Coating, 2

Arch Coating, 6

Wood Coating, 1

Misc Metal Parts, 2

Aerospace, 0.04

Graphic Arts, 1 Auto Refinishing, 4

Landfills, 1

Fugitive V&F, 1

Bulk Terminal, 16

Adhesives, 1

Gasoline Dispensing 

Facilities, 14

Solvent 

Clean/Degreasing, 9

2008 Benefits From District NOx Rules Since 1975 - 20 TPD

Sacramento Nonattainment Area

Boilers, 3

IC Engines, 6

Gas Turbines, 10

Residential Water 

Heaters, 1

Biomass Boilers, 0

Reduction

20

2008

Inventory

10
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Proposed Control Measures

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7.3 Reductions from New State and Federal Control Measures

Since 2007, ARB has adopted a number of statewide measures that will further reduce 

ozone precursor emissions in the Sacramento Metropolitan 8-Hour Ozone 

Nonattainment Area. Listed below are ARB measures adopted since 2007 and sent to 

U.S. EPA as revisions to the SIP or as requests for waivers (Clean Air Act section 

209(b)) or for authorizations (Clean Air Act section 209(e)(2)).

Table 7-1 State Measures Adopted Since 2007

Measure Date of Adoption Date Sent to U.S. EPA

Modifications to Reformulated Gasoline June 14, 2007 Feb. 3, 2009

Vapor Recovery for Above-Ground 

Storage Tanks June 21, 2007 June 12, 2008

Clean Up Existing Harbor Craft Nov. 15, 2007 Apr.12, 2010

Ship Auxiliary Engine Cold Ironing and 

Clean Technology Dec. 6, 2007 Aug. 2, 2010

Consumer Products Program

--2008 amendment

--2009 amendment

June 26, 2008

Sept. 24, 2009

Feb. 16, 2010

Jan. 28, 2011

Additional Evaporative Emission 

Standards Sept. 25, 2008 May 2, 2011

Portable Outboard Marine Tanks Sept. 25, 2008 May 2, 2011

Smog Check Improvements Aug. 31, 2009 Oct. 28, 2009

Pesticides Element Oct. 12, 2009 Aug. 2, 2011

Cleaner In-Use Heavy-Duty Trucks Dec. 16, 2010 Sept. 21, 2011

Cleaner In-Use Off-Road Equipment Dec. 17, 2010 Sept. 21, 2011

The control strategy in the Sacramento Regional 8-Hour Ozone attainment and 

Reasonable Further Progress Plan (Plan) relies on reductions of NOX and VOC to meet 

the 8-hour ozone standards. Because mobile sources are the largest contributors to 

ozone-forming emissions, reducing emissions from passenger vehicles, trucks, and a 

variety of off-road engines is key to attaining the ozone standards. In developing the 

Sacramento Area SIP for meeting the 8-hour standard by 2018, the biggest challenge 

was cleaning up the existing fleets of diesel engines.

Over the past five years, ARB adopted a number of regulations aimed at reducing 

emissions of oxides of nitrogen from existing, “in-use” diesel sources like heavy-duty 

diesel trucks, and off-road sources like large construction equipment. Phased 

implementation of these regulations will produce increasing emission reduction benefits 

over time, as the regulated fleets are retrofitted, and as older and dirtier portions of the 

fleets are replaced with newer and cleaner models at an accelerated pace. ARB’s 

longstanding programs to reduce emissions from passenger vehicles, including the 

smog check program, also provide continuing benefits needed for attainment of the 

ozone standard.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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Proposed Control Measures

Page 7-4

Table 7-2 shows the impact of adopted state measures on projected 2018 emissions in 

the Sacramento Metropolitan 8-Hour Ozone Nonattainment Area. The region also 

compared this Plan to the 2009 Plan to ensure that the revisions do not weaken the 

control measures and strategies. That analysis is summarized in Table 7-2. As the table 

illustrates, the 2009 SIP committed to control measures that have since been adopted 

and incorporated into the emissions inventory, and the 2018 SIP baseline inventory 

minus the expected emissions reductions equals the “Remaining Emissions” after 2009 

SIP implementation. The sum of the 2009 SIP “Remaining Emissions” is higher than the 

“Current Estimate” demonstrating that this 2013 SIP will achieve greater emissions 

reductions than the 2009 SIP. This section describes the adopted measures and 

programs that are providing these reductions.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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Table 7-2: Analysis of ARB's Implemented Regulations using Calendar Year 2018 NOX

Summer Season Emissions (tpd)

Statewide SIP Measures

2009 SIP Summary Current 

Estimate

2018 

Baseline

Expected 

Reductions

Remaining 

Emissions

Remaining 

Emissions

Passenger Vehicles 22.2 1.7 20.5 16.7

Smog Check Improvements (BAR)

22.20

1.4

Expanded Vehicle Retirement 0.3 20.5 16.7

Modifications to Reformulated Gasoline Program 0.0

Heavy-Duty Trucks 22.4 9.5 12.9 12.6

Cleaner In-Use Heavy-Duty Trucks 22.4 9.5 12.9 12.6

Goods Movement Sources 10.3 2.1 8.2 7.0

Accelerated Intro. Of Cleaner Line-Haul Locomotives 9.4 1.9 7.5 6.2

Clean Up Existing Harbor Craft 0.9 0.2 0.7 0.9

Off-Road Equipment 13.4 1.9 11.5 7.0

Cleaner In-Use Off-Road Equipment (over 25hp) 13.4 1.9 11.5 7.0

Other Off-road Sources 6.1 0.3 5.8 2.4

New Emission Standards for Recreational Boats 5.9 0.3 5.6 2.3

Expanded Off-Road Rec. Vehicle Emission Standards 0.1 0.0 0.1 0.1

Additional Evaporative Emission Standards -- -- -- --

Areawide Sources 0.0 0.0 0.0 0.0

Consumer Products Program 0.0 0.0 0.0 0.0

2018 NOX Totals

State SIP Measure Sources1 74 16 59 46

All Other State/Federal Source Categories 9 -- 9 13

District Source Categories2 17 2 15 12

Total Inventory 101 18 83 71

Emission Reduction Credits 33 -- 33 33

Motor Vehicle Emission Budget Safety Margin -- -- -- 3

Total Inventory for Modeling/RFP4 104 18 86 77
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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Proposed Control Measures

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Table 7-2 (continued): Analysis of ARB's Implemented Regulations using Calendar Year 

2018 VOC Summer Season Emissions (tpd)

Statewide SIP Measures

2009 SIP Summary Current 

Estimate

2018 

Baseline

Expected 

Reductions

Remaining 

Emissions

Remaining 

Emissions

Passenger Vehicles 24.9 2.6 22.3 16.3

Smog Check Improvements (BAR)

24.9

1.3

Expanded Vehicle Retirement 0.2 22.3 16.3

Modifications to Reformulated Gasoline Program 1.1

Heavy-Duty Trucks 1.9 0.8 1.1 0.8

Cleaner In-Use Heavy-Duty Trucks 1.9 0.8 1.1 0.8

Goods Movement Sources 0.7 0.1 0.6 0.4

Accelerated Intro. Of Cleaner Line-Haul Locomotives 0.6 0.1 0.5 0.3

Clean Up Existing Harbor Craft 0.1 0.0 0.1 0.1

Off-Road Equipment 7.5 0.4 7.1 6.5

Cleaner In-Use Off-Road Equipment (over 25hp) 7.5 0.4 7.1 6.5

Other Off-road Sources 22.8 6.1 16.7 14.4

New Emission Standards for Recreational Boats 3.0

Expanded Off-Road Rec. Vehicle Emission Standards 22.8 2.7 16.7 14.4

Additional Evaporative Emission Standards 0.4 --

Areawide Sources 15.1 1.9 13.2 13.2

Consumer Products Program 15.1 1.9 13.2 13.2

2018 VOC Totals

State SIP Measure Sources1 73 12 61 52

All Other State/Federal Source Categories 5 -- 5 3

District Source Categories2 40 3 36 39

Total Inventory 117 15 102 94

Emission Reduction Credits 43 -- 43 43

Motor Vehicle Emission Budget Safety Margin -- -- -- 1

Total Inventory for Modeling/RFP4 121 15 106 99

1

State SIP Measure Sources un-truncated. 2013 Plan uses truncated numbers.

2

For the purposes of this table, ERCs are shown separately.

3

ERCs for the 2009 SIP Commitment listed in the 2013 Update, Tables 5-4 and 5-5.

4

The inventory used for this update also serves as a model inventory. For modeling purposes, ERCs 

were distributed across Stationary and Area Source Categories.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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Proposed Control Measures

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Clean New and In-Use Heavy-Duty Trucks

Increasingly stringent standards for new trucks, as shown in the Table 7-2A, are a 

central element of ARB’s emission reduction strategy. New heavy-duty trucks sold since 

2010 emit 98 percent less NOX and PM2.5 than new trucks sold in 1986.

Table 7-2A: Phase-in of truck engine standards

Model Year Applicable Standard

g/bhp-hr

NOX PM

1986 and older 10.7 0.60

1987-2006 From 6.0 to 2.0 From 0.6 to 0.10

2007-2009 1.1 0.01

2010 0.2 0.01

However, older, higher-emitting trucks with long service lives can stay on the road for 

many years, because of the typically slow replacement of older trucks on the road with 

the latest models. Consequently, emissions from existing “on-road” trucks must also be 

reduced to meet near-term air quality standards.

To address this, ARB developed the Cleaner In-use Heavy-duty Truck SIP measure.

This measure leverages the benefits provided by new truck emission standards by 

accelerating introduction of the cleanest trucks. This “Truck and Bus Regulation” was 

adopted in December 2008, and amended in December 2010 to account for the 

reduced emissions resulting from the economic effects of the recession. This rule 

represents a multi-year effort to turn over the legacy fleet of engines and replace them 

with the cleanest technology available. More information is available at: 

http://www.arb.ca.gov/regact/2010/truckbus10/truckbus10.htm.

Starting in 2012, the Truck and Bus Regulation phases in requirements so that by 2023 

nearly all vehicles will meet 2010 model year engine emissions levels. The regulation 

applies to nearly all diesel fueled trucks and buses with a gross vehicle weight rating 

greater than 14,000 pounds that are privately or federally owned, including on-road and 

off-road yard goats, and privately and publicly owned school buses. Moreover, the 

regulation applies to any person, business, school district, or federal government 

agency that owns, operates, leases or rents affected vehicles. The regulation also 

establishes requirements for any in-state or out-of-state motor carrier, California-based 

broker, or any California resident who directs or dispatches vehicles subject to the 

regulation. Finally, California sellers of a vehicle subject to the regulation would have to 

disclose the regulation’s potential applicability to buyers of the vehicles.

In addition to the Truck and Bus Regulation, separate regulations reduce emissions 

from on-road vehicles in public fleets, including solid waste collection trucks and transit 
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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buses. Trucks that transport marine containers must comply with the drayage truck 

regulation.

Cleaner In-Use Off-Road Equipment

ARB has also adopted increasingly stringent standards for engines used in new off-road 

diesel equipment. As a result of these standards, new construction, mining, industrial 

and oil drilling equipment will become progressively cleaner. The requirements vary 

according to the power rating of engines. Table 7-2B shows the schedule for phasing in 

tiered requirements for new off-road engines with a power rating between 175 and 300 

horsepower (hp). Beginning in 2014, new Tier 4 construction equipment with the power 

rating shown below will emit about 96 percent less NOX and PM than new Tier 1 

equipment sold in the year 2000.

Table 7-2B: Phase-in of off-road engine standards

Model year Level of Control Applicable Emission Standard for

New Off-road Engines 175<hp<300

g/bhp-hr

NOX PM

1996-2002 Tier 1 6.9 0.4

2003-2005 Tier 2 4.9* 0.15

2006-2010 Tier 3 3.0* 0.15

2011-2013 Tier 4 interim 1.5 0.015

2014+ Tier 4 final 0.3 0.015

*Reflects combined limit for non-methane hydrocarbons and NOX

However, large diesel off-road equipment typically remains in use for many years, if not 

decades. As with heavy-duty trucks, this long life means that newer, lower-emitting 

engines would be introduced into fleets relatively slowly, which will also delay the 

emission reductions and associated health benefits from these cleaner engines. To 

address this, the State Strategy for California’s 2007 SIP included the Cleaner In-use 

Off-road Equipment measure, the “Off-Road Regulation.”

First approved in 2007, the Off-Road Regulation was amended in 2010 in light of the 

impacts of the economic recession. Affected off-road equipment is used in construction, 

manufacturing, the rental industry, road maintenance, airport ground support, and 

landscaping. In December 2011, the Off-Road Regulation was modified to include onroad trucks with two diesel engines. More information is available at: 

http://www.arb.ca.gov/regact/2010/offroadlsi10/offroadlsi10.htm.

The Off-Road Regulation will significantly reduce emissions of diesel PM and NOX from 

the over 150,000 in-use off-road diesel vehicles that operate in California by requiring 

their owners to modernize their fleets and install exhaust retrofits. The regulation affects 

dozens of vehicle types used in thousands of fleets by requiring owners to modernize 
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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their fleets by replacing older engines or vehicles with newer, cleaner models, by retiring 

older vehicles or using them less often, or by applying retrofit exhaust controls.

The Off-Road Regulation imposes idling limits on off-road diesel vehicles, requires a 

written idling policy, and requires a disclosure when selling vehicles. The regulation also 

requires that all vehicles be reported to ARB, restricts the addition of older vehicles into 

fleets, and requires fleets to reduce their emissions by retiring, replacing, or repowering 

older engines, or installing verified exhaust retrofits. The requirements and compliance 

dates of the Off-Road Regulation vary by fleet size.

Advanced Clean Cars

The Board established California’s Low Emission Vehicle (LEV) program in 1990 and 

the LEV2 program in 1998. ARB’s Zero Emission Vehicle (ZEV) regulation, which 

affects passenger cars and light-duty trucks, has also spurred movement towards 

commercialization of advanced clean cars and light-duty trucks. As a result, many new 

gasoline engines now emit extremely low levels of smog forming emissions.

Conventional hybrid electric vehicles have been commercialized, and the number of 

models offered for sale is quickly expanding. Recently battery electric vehicles and plugin hybrid electric vehicles have been introduced for sale, and fuel cell electric vehicles 

are expected to follow.

ARB’s Advanced Clean Cars (ACC) Program, approved in January 2012, is a 

pioneering approach of a ‘package’ of regulations, that although separate in 

construction, are related in terms of the synergy developed to address both ambient air 

quality needs and climate change. The ACC program combines the control of smog, 

soot causing pollutants and greenhouse gas emissions into a single coordinated 

package of requirements for model years 2015 through 2025. The program assures the 

development of environmentally superior cars that will continue to deliver the 

performance, utility, and safety vehicle owners have come to expect.

The ACC program includes amendments affecting the current ZEV regulation through 

the 2017 model year to enable manufacturers to successfully meet 2018 and 

subsequent model year requirements. The ZEV amendments are intended to achieve 

commercialization by simplifying the regulation and pushing technology to higher 

volume production to achieve cost reductions.

The ACC Program will produce increasing benefits over time as new cleaner cars enter 

the fleet, displacing older and dirtier vehicles. This program will continue to provide 

benefits well after 2019 as vehicles meeting the new standards replace older, higheremitting vehicles.

Many additional programs are currently in place to reduce emissions from the 

passenger car legacy fleets and accelerate fleet turn over. The Smog Check Program 

ensures that passenger vehicles stay clean as they age and on-board diagnostic 
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systems identify smog control problems. The Smog Check Program is continuously 

being improved to provide additional emission reductions such as requiring stricter 

inspection standards and annual inspection of older vehicles. ARB is also active in 

encouraging consumers with older dirtier vehicles to retire them early. Replacing older 

dirtier vehicles with cleaner new vehicles provides permanent emission reductions.

Expanded Passenger Vehicle Retirement

Voluntary accelerated vehicle retirement or “car scrap” programs provide monetary 

incentives to vehicle owners to retire older, more polluting vehicles. The purpose of 

these programs is to reduce fleet emissions by accelerating the turnover of the existing 

fleet and subsequent replacement with newer, cleaner vehicles. Reducing emissions 

from the existing fleet is a component of California’s SIP, which outlines the State’s 

strategy for meeting health-based ambient air quality standards. Both State and local 

vehicle retirement programs are available.

California’s updated voluntary vehicle retirement program is administered by the Bureau 

of Automotive Repair (BAR) and provides $1,000 per vehicle and $1,500 for low-income 

consumers for unwanted vehicles that meet certain eligibility guidelines. This program is 

referred to as the Consumer Assistance Program.

The Enhanced Fleet Modernization Program (EFMP) was approved by the AB 118 

legislation to augment the State’s existing vehicle retirement program. Approximately 

$30 million is available annually through 2015 to fund the EFMP via a $1 increase in 

vehicle registration fees. ARB developed the program in consultation with BAR. The 

program is jointly administered by both BAR for vehicle retirement, and local air districts 

for vehicle replacement.

Other programs, in addition to vehicle retirement programs, help to clean up the light 

duty fleet. The Air Quality Improvement Program (AQIP), established by AB 118, is an 

ARB voluntary incentive program to fund clean vehicle and equipment projects. The 

Clean Vehicle Rebate Project (CVRP) is one of the current projects under AQIP. CVRP, 

started in 2009, is designed to accelerate widespread commercialization of zeroemission vehicles and plug-in hybrid electric vehicles by providing consumer rebates up 

to $2,500 to partially offset the higher cost of these advanced technologies. These 

vehicles are a key element of California’s strategy for meeting health based air quality 

standards and climate change goals.

The CVRP is administered statewide by the California Center for Sustainable Energy. In 

Fiscal Years 2009-2012, $26.1 million, including $2 million provided by the California 

Energy Commission, funded approximately 2,000 rebates. In June 2012, the ARB 

allocated up to $21 million to the CVRP as outlined in the AQIP FY2012-2013 Funding 

Plan.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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Improvements and Enhancements to California’s Smog Check Program

The following requirements were added to improve and enhance the Smog Check 

Program:

• Low pressure evaporative test;

• More stringent pass/fail cutpoints;

• Visible smoke test; and

• Inspection of light- and medium-duty diesel vehicles.

AB 2289, adopted in October 2010, restructured California’s Smog Check Program by 

streamlining and strengthening inspections, increasing penalties for misconduct, and 

reducing costs to motorists. This new law, sponsored by ARB and BAR, promises faster 

and less expensive Smog Checks by taking advantage of diagnostic software installed 

on all vehicles since 2000. The new law also directs vehicles without this equipment to 

high-performing stations, helping to ensure that these cars comply with current emission 

standards.

This program will reduce consumer costs by having stations take advantage of 

diagnostic software that monitors pollution-reduction components and tailpipe 

emissions. This technology, known as On-Board Diagnostics (OBD), has been required 

on all new vehicles since 1996. Under the new law, testing of passenger vehicles using 

OBD will begin mid-2013 on all vehicles model years 2000 or newer. Statewide, this is 

expected to reduce consumer costs by up to $180 million annually.

Accelerated Introduction of Cleaner Line-Haul Locomotives

California leads the nation with the most extensive efforts to reduce locomotive and rail 

yard emissions. In 2007 ARB staff proposed to replace existing switch and medium 

horsepower locomotives with cleaner locomotives; retrofitting these locomotives with 

particulate matter and NOX after-treatment devices, and accelerating the introduction of 

cleaner new Tier 4 interstate line-haul locomotives to operate in California and other 

western states. ARB completed 18 major rail yard health risk assessments that showed 

increased risk for those who live and work near these facilities.

The Union Pacific (UP) rail yards located in Roseville has benefitted from numerous 

programs targeting NOX and PM emissions. ARB utilized Proposition 1B funding for 15 

Tier 2 “regional” line haul locomotives. The UP also operates 6 ultra-low emitting genset 

switch locomotives within the Roseville rail yards. The UP 9900, an experimental Tier 

3+ locomotive (Tier 4 PM, and Tier 3+ NOX), has been assigned to UP Roseville and 

operates primarily in Northern California. Finally, the California interstate line haul 

locomotive fleet has become significantly cleaner than the rest of the country due to the 

spillover benefits from the 1998 Locomotive NOX Fleet Average Agreement in the South 

Coast Air Basin. Emissions within Sacramento’s Nonattainment area have been 

reduced by about 42 percent from the 2002 baseline.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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Consumer Products

Under State law, ARB has regulatory responsibility for reducing VOC emissions from 

consumer products. Since 2005, consumer products regulations adopted by ARB 

reduce VOC levels in significant, but previously unregulated, sectors of commerce and 

ban the use of toxic and high global warning potential chemicals in these and previously 

regulated sectors.

On November 17, 2006, ARB approved amendments to the Consumer Products 

regulations including automotive care products, cleaners, degreasers, disinfectants, 

adhesives, fabric care products, personal care products, and waxes and polishes. On 

June 26, 2008, the ARB approved amendments that include household cleaning and 

degreasing products, home and garden pesticides, aerosol paints, personal care 

products, and automotive maintenance products. These amendments have been 

approved by the EPA, and the effects are reflected in the inventory used in this update.

7.4 Consideration and Selection of New Regional and Local Control Measures

EPA’s final 8-hour ozone implementation rule72 (see section 172(c)(1) of the Clean Air 

Act) requires “a SIP revision demonstrating that it has adopted all reasonably available 

control measures (RACM) necessary to demonstrate attainment as expeditiously as 

practicable and to meet any RFP requirements.” EPA’s RACM policy73 indicates that 

areas should consider all candidate measures that are potentially reasonably available.

Sources of potentially reasonable measures include measures adopted in other 

nonattainment areas, measures that the EPA has identified in guidelines or other 

documents, and any measures that have been suggested for the particular 

nonattainment area during a public comment period.

Areas should consider all reasonably available measures for implementation in light of 

local circumstances. However, areas need only adopt measures if they are both 

economically and technologically feasible and cumulatively will either advance the 

attainment date by one year or more or are necessary for RFP. The emission reductions 

needed to attain 1 year earlier would be the difference in the emission forecasts 

(including new proposed control measures) between 2017 and 2018.

This plan contains required reasonably available control measures. Documentation,

analysis, and conclusions regarding each control measure are provided in Appendix H –

Reasonably Available Control Measures Analysis.

7.5 SIP Control Measure Commitments

 

72 “Final Rule to Implement the 8-Hour Ozone National Ambient Air Quality Standard – Phase 2” (Federal 

Register, November 29, 2005, p. 71659-71661).

73 “Guidance on the Reasonably Available Control Measures (RACM) Requirement and Attainment 

Demonstration Submissions for Ozone Nonattainment Areas” (EPA, December 1999).
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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Proposed Control Measures

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To achieve the additional emission reductions needed for attaining the 1997 federal 8-

hour ozone standard, the implementation of new control measures are proposed as a 

SIP commitment. The total emission reductions and the obligation to propose specific 

new measures would become federally enforceable upon approval by U.S. EPA of the 

control measures in the attainment plan. The commitments for emission reductions are 

calculated using the planning emissions inventory, and progress will be tracked in the 

same inventory currency to assess compliance.

The total emission reductions from the new measures necessary to attain the federal 

standards are an enforceable commitment in the SIP. While the proposed regional and 

local control measures include estimates of the emission reductions from each of the 

individual measures, it is important to note that the commitment is to achieve the total 

emission reductions necessary to attain the federal standards. Therefore, if a particular 

measure or a portion thereof is found infeasible or does not get its expected emission 

reductions, each air district still commits to achieving the total aggregate emission 

reductions necessary for attainment, whether this is realized through additional or 

surplus reductions from the other adopted measures, from alternative control measures, 

or incentive programs.

Although the regional and local commitment is to the "total emission reductions," for 

purposes of transportation conformity, an explicit commitment is made to the reductions 

associated with the on-road mobile source incentive program. Also, the urban forest 

control measure, SMAQMD-1, is an emerging measure. Because of the uncertainties 

associated with implementation and validation of this urban forest measure, the 

emission benefits from this strategy are not included in the attainment or reasonable 

further progress demonstrations.

Should future air quality modeling or air quality improvements indicate that all of the 

emission reductions from the new measures are not necessary for attainment and an 

infeasibility finding is made for a control measure or a portion thereof, the region's SIP 

commitment can be adjusted downward. For purposes of SIP commitment, infeasibility 

means that the proposed control technology is not reasonably likely to be available by

the implementation date needed, or achievement of the emission reductions by that 

date is not cost-effective or technologically feasible because of local circumstances.

7.6 SIP Emission Reduction Tracking

For purposes of tracking progress in emission reductions, the baseline emissions for the 

year 2002 and for milestone years in this plan will be used, regardless of any 

subsequent new inventory information that reflects more recent knowledge. This is to 

ensure that the same “currency” is used in measuring progress as was used in 

designing the ozone attainment and RFP plan. This will provide a fair and equitable 

measurement of progress.

7.7 Non-regulatory Control Measures
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Proposed Control Measures

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The non-regulatory control measures proposed in this 8-hour ozone plan are regional

programs that will achieve emission reductions throughout the Sacramento 

nonattainment area. The following non-regulatory measures are proposed:

 Mobile Source Incentive Measures – On-road and Off-road

 Spare The Air Program

 SACOG Transportation Control Measures

 Urban Forest Development Program

7.8 Mobile Source Incentive Measures

Mobile sources such as trucks, automobiles, trains, boats, construction and farm 

equipment are by far the largest sources of ozone precursors in the Sacramento 

nonattainment area. Included under this major source category are all non-stationary 

sources from lawn mowers to jumbo jets. The air districts do not have authority to 

directly regulate mobile source emissions through emission standards; however, the air 

district incentive programs may complement state and federal regulatory efforts in 

reducing mobile source emissions. These regional mobile source incentive measures 

are implemented in all or parts of the Sacramento nonattainment area by the air 

districts.

The estimated emission reductions from the proposed regional mobile incentive 

measures are summarized, followed by descriptions of the individual on-road mobile

and off-road mobile control measures. Because many of the incentive measures in the 

mobile source categories target the same vehicles or engines, it is difficult to predict in 

advance what portion of the benefits should be assigned to each of the individual 

strategies. Therefore, the benefits from the collection of measures have been estimated, 

and all or any portion of the measures may be implemented to achieve those benefits.

Some measures noted may likewise not be implemented if cost effective reductions are 

not available. However, for purposes of transportation conformity, an explicit 

commitment is made to the reductions associated with the on-road mobile source 

incentive program.

Control Measure Adoption

Year

Implement

Year

Emission Reduction (TPD)

2018

VOC NOX

Mobile Source Incentive 

Programs 2012 2008-2018 <0.1 0.5

The incentive program measures rely on funding provided according to existing laws 

and policies. The funding sources for 2008-2018 include SECAT program ($33.0M) and

local district Department of Motor Vehicle fees ($13.0M).

On-road Measures

The on-road motor vehicle category includes trucks, automobiles, buses and 

motorcycles. The on-road emissions inventory includes estimates of exhaust and 
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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Proposed Control Measures

Page 7-15

evaporative emissions. Regional measures for reducing on-road vehicle emissions 

include the use of financial incentives to promote the accelerated introduction of low 

emission vehicle, engine, and fuel technologies to the Sacramento region.

ONMS-HD-1: SECAT-Like Program

This measure implements an incentive program for NOX reduction in heavy-duty 

vehicles similar to that created by the Sacramento Emergency Clean Air Transportation 

(SECAT) program. Incentives would be distributed on a dollar per ton basis. The level of 

reductions is based on both the amount of money available and the options available to 

specific trucks. This measure is implemented annually through the attainment year 

(2008-2018).

ONMS-LD-1: Light Duty Early Retirement 

This measure would implement an incentive based light-duty vehicle early retirement 

program for non-OBD-II vehicles74. Light duty scrappage programs have been 

successfully implemented in the SCAQMD and the Bay Area. This program would be 

based upon the Bay Area program, providing cash incentives to retire registered, 

working vehicles early. The program would require more monitoring than is currently 

performed in other programs to ensure emission reductions are achieved and would 

require replacement with at least ULEVs. No incentives for purchase of new vehicles 

are provided in the measure. This measure is implemented from 2009-2014. The 

specific program details, quantification methods, auditing, and reporting will be adopted 

and submitted separate from this SIP document.

Control Measure Adoption

Year

Implement

Year

Emission Reduction (tpd)

2018

VOC NOX

Mobile Source Incentive 

Programs - On-road 2012 2008-2018 <0.1 0.5

Off-road Measures

The off-road mobile source category encompasses a wide variety of sources including 

small off-road engines and equipment, off-road recreational vehicles, farm and 

construction equipment, forklifts, locomotives, commercial marine vessels, and marine 

pleasure craft. Regional measures for reducing off-road emissions include the use of 

financial incentives to accelerate voluntary retirement or retrofit of older, high emitting 

equipment, resulting in reduced off-road emissions.

 

74 OBD is abbreviation for onboard diagnostics
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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Proposed Control Measures

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OFMS-HD-1: Off-road CI Incentive Program

This measure implements an incentive program for NOX reductions through aftertreatment retrofits, engine repowers, and fleet modernization in off-road heavy-duty 

compression ignition (CI) equipment. Incentives would be distributed on a dollar per ton 

basis. This measure is implemented from 2008-2014.

OFMS-SI-1: Zero Emission Lawn and Garden Incentive (Residential)

This measure would implement a year-round continuous incentive program for the 

replacement of residential spark ignited (SI) gasoline-powered mowers with electric or 

zero emission alternatives. Cash incentives per mower replaced will be offered in 

exchange for SI equipment through local retailers. Eligible equipment is primarily limited 

to lawn mowers with engines less than five horsepower. The measure is implemented 

from 2008-2014.

Control Measure Adoption

Year

Implement

Year

Emission Reduction (tpd)

2018

VOC NOX

Mobile Source Incentive 

Programs - Off-road 2012 2008-2014 <0.1 <0.1

7.9 “Spare The Air Program”

The “Spare The Air” control measure is a year-round public education program with an 

episodic ozone reduction element during the summer ozone season, plus general 

awareness throughout the rest of the year. It is designed to protect public health by 

informing people when air quality is unhealthy and achieving voluntary emission 

reductions by encouraging them to reduce vehicle trips. This program is implemented 

by the SMAQMD staff on behalf of the region. Funding for this program has historically 

been federal Congestion Management and Air Quality (CMAQ) funds, with local 

matching funding provided by each air district’s DMV and/or Sacramento County’s 

Measure A funding. CMAQ funding ($600,000 per year) has been included in the 

SACOG MTP2035 through 2018.

Since transportation control measures (TCMs) are strategies for reducing vehicle trips, 

vehicle use, vehicle miles traveled, vehicle idling, or traffic congestion for the purpose of 

reducing motor vehicle emissions, the Spare The Air program is proposed as a TCM in 

this SIP. The estimated emission reductions from this program are provided in the 

following table.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Proposed Control Measures

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Control Measure Adoption

Year

Implement

Year

Emission Reduction (tpd)

2018

VOC NOX

Spare The Air Program 

(TCM-ONMS-ED-1) 2009 2008-2018 <0.1 <0.1

7.10 SACOG Transportation Control Measures

Transportation control measures (TCMs) are strategies for reducing vehicle trips, 

vehicle use, vehicle miles traveled, vehicle idling, or traffic congestion for the purpose of 

reducing motor vehicle emissions. The Sacramento Area Council of Governments 

(SACOG) is the Metropolitan Planning Organization (MPO) for the greater Sacramento 

region (includes Sacramento, Yolo, Placer, El Dorado, Sutter, and Yuba counties).

SACOG provides transportation planning and funding for the region. SACOG, local 

governments, and the air districts have worked together over the years to develop and 

implement TCMs. They have included public transit, carpooling and vanpooling, 

bicycling and pedestrian enhancement, and land use programs. The Spare The Air 

program is also a TCM.

TCMs are included in the “smart growth” assumptions for the Blueprint program used in 

the SACOG transportation model to forecast future vehicle activity. Federal MTP 

guidelines require that the land use allocations represent what is most likely to be built.

Therefore, the specific Blueprint smart growth policies affect land use allocations only to 

the extent that the local jurisdictions and SACOG are able to demonstrate that the 

policies will actually be implemented. These updated activity data were used in setting 

the baseline projections for the motor vehicle inventory. While the Blueprint principles 

affect these baseline projections, Blueprint is not included in this plan as a 

transportation control measure.

There are transportation planning implications associated with including TCMs in a SIP.

Every time the MPO makes a conformity determination to accompany a new 

Metropolitan Transportation Plan (MTP), a new Metropolitan Transportation 

Improvement Program (MTIP), or an amendment to either document, it must 

demonstrate that all TCMs are still on track to be implemented in a timely fashion. If a 

TCM does not stay on schedule, the MPO must show that all State and local agencies 

with influence over approvals or funding for TCMs are giving maximum priority to 

approval or funding of TCMs over other projects within their control. The MPO and any 

other responsible agencies would have to either ensure that the TCM is able to get back 

on schedule, or be able to substitute another TCM. In other words, the MPO may not be 

able to demonstrate conformity on a new or amended MTP or MTIP if a TCM is failing.

In addition, the Transportation Conformity Rule (40 CFR 93.103) states, “When 

assisting or approving any action with air quality-related consequences, FHWA and FTA 

shall give priority to the implementation of those transportation portions of an applicable 

implementation plan prepared to attain and maintain the NAAQS.”
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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7.11 New and Continuing TCM Projects

All of the following new and continuing TCM projects75 chosen to be included in the 

federal 8-hour ozone plan were selected because they had early completion dates, 

costs were not large, funding was already committed, and delivery appeared to be 

likely. Additional information and documentation of the TCM projects are included in 

Appendix D – Transportation Control Measures.

Intelligent Transportation Systems (ITS) Projects 

SACOG is working with local partners to plan and implement Intelligent Transportation 

Systems (ITS) projects to improve traffic flow and reduce vehicle emissions. ITS 

projects use advanced technology and tools such as freeway ramp meters, dynamic 

message signs, and traffic signal timing to provide real-time information on traffic 

conditions and coordinate operations at local traffic centers.

 Arden Way “Smart Corridor” from Del Paso to Watt – Smart Corridor on Arden 

Way from Del Paso to Watt Avenue.

 Sacramento Traffic Operations Center – evaluate and implement on downtown 

and other major corridors, ITS elements and infrastructure necessary to provide 

traffic responsive/coordinated signal timing and communications to the Traffic 

Operation Center.

 STARNET Implementation – develop and install an information exchange system 

called the Sacramento Transportation Area Network (STARNET), and connect 18 

traffic and emergency centers.

Park and Ride Lots / Transit Centers

 El Dorado Central Park and Ride Facility – construct Central Transfer Facility and 

Park & Ride with capacity for 95 spaces in Diamond Springs, on Commerce Way at 

State Route 49.

 Improvements to Loomis Multimodal Center – design and construct pedestrian 

and landscaping improvements at the multimodal center including a Class I bike 

facility adjacent to Taylor Road from downtown Loomis to Sierra College Blvd.

 13th and 16th Street Light Rail Station Improvements – construct improved 

pedestrian access, lighting, and signage at 13th and 16th Street Light Rail Stations in 

Sacramento.

Transit Service Funding Programs

 

75 These TCMs were approved for inclusion by SACOG Board (August 21, 2008, Consent Item #08-8-10).
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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Proposed Control Measures

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Travel by transit is of great interest in the Sacramento region for several reasons. First, 

transit provides an opportunity for reducing VMT and emissions, through shifts from lowoccupancy modes like driving alone to a very high occupancy mode of travel. Second, 

for commute trips, which tend to occur at peak periods of travel demand when 

congestion is highest, transit can provide substantial congestion relief. Finally, high 

quality transit service can provide necessary mobility to residents and employees in 

higher density, mixed use areas, where auto travel can be impractical. For these 

reasons, SACOG proposes making a commitment to maintain existing levels of transit 

service through the following TCMs:

 Transit Vehicle Acquisitions - fund the following bus purchases:

SACOG Measure Title Cost

Auburn Transit Bus Replacement $225,000 

Roseville Transit Bus Purchase $2,300,000 

Roseville Transit Bus Replacement $375,000 

Replacement Neighborhood Ride Buses $255,000 

E-Tran Replacement Buses $1,400,000 

SRTD Neighborhood Ride Vehicle Replacement $3,600,000 

Yuba Sutter Transit Bus Expansion $1,500,000 

YCTD Bus Replacement $1,700,000 

 Transit Operations – fund the following transit operations:

SACOG Measure Title Cost

El Dorado Transit Operating Assistance $580,000 

Roseville Operating Assistance $145,000 

Elk Grove Operating Assistance $1,800,000 

Folsom Operating Assistance $745,000 

Paratransit Operating Assistance $350,000 

Sacramento County Operating Assistance $59,000 

Regional Transit Operating Assistance $364,000,000 

YCTD Operating Assistance $1,100,000 

Other Specific Funding Programs

 Freeway Service Patrol - Sacramento County: provide motorist assistance and 

towing of disabled vehicles during a.m. and p.m. commute periods on various 

highways in Sacramento County and a portion of I-80 in Yolo County.

 Sacramento Emergency Clean Air Transportation (SECAT) Program - HeavyDuty NOX control strategies; SECAT program; GIS Transit program (includes bus 

stop and centralized regional transit information system, and trip planning). Bus 

Replacement projects include: REG17782, YCT18087, UNI10441, SAC24145, 

PCT10481.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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 “Spare The Air” Program - conduct the Spare The Air Education Program, jointly 

funded by the Sacramento Metropolitan AQMD, Yolo-Solano AQMD, and the Placer 

County APCD.

MTP Regional Funding Programs

The Metropolitan Transportation Plan (MTP) includes four federally-funded programs to 

be used for regional transportation and related priorities that implement the goals of the 

MTP. This TCM is a SACOG commitment to continue to implement the MTP Funding 

Program for the following:

 Air Quality Funding Program – includes projects under Other Specific Funding 

Programs (Freeway Service Patrol, SECAT Program, and “Spare The Air” Program).

 Bicycle and Pedestrian Funding Program – to provide facilities for walking and 

biking in the cities and towns of the region, or to provide connections between them, 

and includes the following list of projects:

Adopted Projects from SACOG's Regional Bike/Pedestrian Funding 

Program Cost

City of Sacramento: I-80 Bike/Ped Bridge at the West Canal $6,600,000

City of Folsom Bikestation and "Bikelink" On-Demand Long-Term 

Class I Bike Parking at Transit Stations $178,000

City of Elk Grove: Elk Grove Creek Bike/Ped Bridge Crossing at SR 99 $5,600,000

Retrofit Yolobus bus fleet with higher capacity bike racks $67,500

 Transportation Demand Management (TDM) Funding Program – composed of 

strategies that can lower the demands made on the road and highway system and 

improve air quality by encouraging the use of carpooling, vanpooling, public transit, 

bicycling, and walking. The goal is to reduce single-occupant vehicle trips in the 

Sacramento region using TDM strategies and measure the effects of these 

strategies.

SACOG currently operates the regional ridesharing database and performs a number 

of marketing activities that publicize TDM strategies to the public. SACOG also 

sponsors the TDM Task Force, a group of Transportation Management Associations 

(TMAs) and other organizations that perform or promote TDM services for employers 

and residents of the region.

This measure includes funding the following program:

SACOG Measure Title Cost

SACOG Regional Rideshare Program $1,200,000 through 2018
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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Proposed Control Measures

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 Community Design Funding Program – to provide support and financial incentives 

to local governments for planning and capital development projects that promote and 

implement the Blueprint Project principles. Grants are awarded to projects sponsored 

by qualified public agencies in the SACOG region that conform to the seven Blueprint 

principles: 1) transportation choices, 2) housing diversity, 3) compact development, 

4) mixed land uses, 5) use of existing assets, 6) natural resource protection, and 7) 

quality design.

The Community Design program results from the recognition that land use influences 

travel behavior and can be a powerful tool to improve the efficiency and effectiveness 

of the regional transportation system. Land use and projects that lead to fewer 

vehicle miles traveled and more walking, biking, and transit usage can provide air 

quality and congestion-relief benefits at the local and regional scale.

This measure includes funding the following projects:

Adopted Projects from SACOG's Regional Community Design 

Funding Program Cost

City of Marysville: East 10th Street and Ramirez Street Intersection 

Improvement $510,000

City of Rancho Cordova: Folsom Boulevard Complete Streets $12,200,000

Sacramento County: Complete Streets for Freedom Park Drive and 

North Watt Avenue $6,400,000

City of Woodland: Lemen, North, East Streets Intersection 

Realignment $2,600,000

Miscellaneous Projects

 Light Rail Grade Separation at Watt Avenue and Folsom Boulevard – in 

Sacramento County, Regional Transit Light Rail tracks south of Folsom Blvd. on Watt 

Ave., grade separate the rail tracks over Watt Ave.

 Dry Creek Parkway Trail, Phase 1 – In Sacramento County, Rio Linda-Dry Creek 

Parkway, from Dry Creek Road at Dry Creek Ranch to the Cheery Island Soccer 

Complex: Construct a 3-mile Class I shared-use bicycle/pedestrian trail.

Summary of SACOG New and Continuing TCM Projects and Funding Programs

Table 7-3 contains a summary of SACOG new and continuing transportation control 

measure (TCM) projects and funding programs that are being included in the federal 8-

hour ozone plan. Also listed are the implementing agencies, the predicted 

implementation or completion dates, and the estimated VOC and NOX emission 

reductions, if quantified.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

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Table 7-3

Summary of SACOG Transportation Control Measures

New and Continuing Projects and Funding Programs

TCM Name and (ID) Implementing 

Agency

Implement or 

Completion 

Date

VOC

Reduction

(Tons/Day)

NOX

Reduction

(Tons/Day)

Intelligent Transportation Systems 

(ITS) Projects

Arden Way Smart Corridor (ITS-1) City of Sac - Dept of 

Transportation 2008 --- ---

Sacramento Traffic Operations 

Center (ITS-2)

City of Sac - Dept of 

Transportation 2009 --- ---

STARNET Implementation (ITS-4) SACOG 2009 --- ---

Park and Ride Lots / Transit Centers

El Dorado Central Park and Ride 

Facility (TF-1)

El Dorado County 

Transit 2009 --- ---

Improvements to Loomis Multimodal 

Center (TF-2)

Town of Loomis –

Dept of Public Works 2010 --- ---

13th and 16th St :Light Rail Station 

Improvements (TF-3)

Sac Regional Transit 

District 2009 --- ---

Transit Service Funding Programs

Transit Vehicle Acquisitions (TR-1) Various Agencies Various 

Dates --- ---

Transit Operations (TR-2) Various Agencies Various 

Dates --- ---

Other Specific Funding Programs

Freeway Service Patrol (AQ-1) Sac Transportation 

Authority Through 2018 --- ---

SECAT Program (AQ-2) SMAQMD Through 2018 ---

a

---

a

Spare The Air Program (AQ-3) SMAQMD Through 2018 ---

b

---

b

MTP Regional Funding Programs

Air Quality Funding Program (FP-1) Various Agencies Through 2018 --- ---

Bicycle and Pedestrian Funding 

Program (FP-2) Various Agencies Through 2018 --- ---

Transportation Demand 

Management Funding Program (FP3)Various Agencies Through 2018 --- ---

Community Design Funding 

Program (FP-4) Various Agencies Through 2018 --- ---

Miscellaneous Projects

Light Rail Grade Separation at Watt 

Ave and Folsom Blvd (M-2)

Sac County – Dept of 

Transportation 2009 --- ---

Dry Creek Parkway Trail Phase 1 Sac County – Dept of 

Transportation 2011 --- ---

Total Emission Reductions --- ---

a SECAT emission reductions are assumed to be included in SMAQMD mobile source control measure 

ONMS-HD-1.

b Spare The Air emission reductions are assumed to be included in SMAQMD control measure TCM-ONMSED-1.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Proposed Control Measures

Page 7-23

7.12 Research and Policy Development TCMs

The research efforts listed below are included as TCMs because they are expected to 

result in policies that will help improve the region’s air quality. Since these measures are 

only in the preliminary “study” stage, it is not possible to quantify the potential emission 

reductions from policies developed as a result of the studies. Consequently, no 

associated emissions reduction benefits are included as part of this SIP. Instead, 

emissions reductions for future adopted policies will be accounted for in future SIPs.

The SIP does include a present commitment to adopt the Complete Streets Policy and 

Safe Route to School Policy TCMs. The following Table 7-4 lists the recommended 

research and policy development TCMs:

Table 7-4

Summary of SACOG Transportation Control Measures

Research and Policy Development Studies

1. Blueprint Implementation & Planning Technical Assistance

2. Develop Rural-Urban Connections Strategy & Best Practices Toolkit

3. Research a Transportation Pricing Policy

4. Research a Regional Parking Regulation Policy

5. Adopt a Complete Streets Policy

6. Initiate a Complete Streets Technical Assistance Program

7. Adopt a Safe Routes to School Policy and Implement a Pilot Program

Blueprint Implementation & Planning Technical Assistance

To implement the Blueprint Project’s vision and “smart growth” principles through 

existing and new programs, SACOG will: 1) continue to fund the regional Community 

Design Grant Program, 2) develop a form-based zoning code handbook, 3) provide 

evaluations of proposed development projects for Blueprint consistency, and 4) provide 

technical planning assistance in the development or update of local government plans.

Develop Rural-Urban Connections Strategy & Best Practices Toolkit

SACOG will develop a Rural-Urban Connections Strategy to expand on and support 

implementation of the Blueprint growth strategy and the MTP. The Rural-Urban 

Connections Strategy will utilize state-of-the-art data collection, modeling, research and 

participation methods to develop a toolkit of best practices to enhance land use 

planning practices in rural areas that are both economically viable for land owners and 

local governments and environmentally sustainable.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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Proposed Control Measures

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Research a Transportation Pricing Policy

SACOG will prepare an analysis on the impacts and viability of using pricing policies 

with the transit system and selected portions of the road network to encourage people 

to drive less and use transit, walking, and bicycling modes more.

Research a Regional Parking Regulation Policy

SACOG will perform travel modeling and air emissions analysis to identify a range of 

alternatives for local governments to use to modify current parking regulations to create 

incentives for people to use available transit, walking and biking options, and 

neighborhood electric vehicles. This study will be conducted cooperatively with key 

partners such as the air districts and local governments within the region.

Adopt a Complete Streets Policy

SACOG will adopt a “Complete Streets” policy to require that applicants for SACOG 

regional funding programs demonstrate that the planning, design, construction and 

maintenance of roadway and transit facilities include the needs of all transportation 

users – pedestrians, bicyclists, the disabled, transit users, and motorists.

Initiate a Complete Streets Technical Assistance Program

To implement the Complete Streets policy, SACOG will review and analyze the 

practices of local governments within the SACOG region and around the nation to 

identify appropriate “Best Practices” for complete street design within the SACOG 

region. SACOG will also provide technical assistance to local governments on a case by 

case basis, as requested, to help them successfully implement this concept.

Adopt a Safe Routes to School Policy and Implement Pilot Program

SACOG will adopt a Safe Routes to Schools (SRTS) policy to promote the practice of 

safe bicycling and walking to and from schools throughout the MTP Plan Area to reduce 

traffic congestion, improve air quality, and enhance neighborhood safety. SACOG will

also obtain federal funds from the Federal Highway Administration through Caltrans to 

implement at least one SRTS pilot program within the MTP Plan Area.

7.13 Urban Forest Air Quality Development Program

Emerging and Voluntary Measures

It is imperative today that we look for new and innovative strategies to include in the SIP 

to offset the impacts of anthropogenic emissions. Emerging control measures are 

control strategies based on science and technology that are new, difficult to quantify, 

and do not possess the high level of certainty normally found in traditional control 
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measures. Voluntary measures are strategies that will result in the reduction of a criteria 

pollutant or precursor that the State could claim as an emission reduction in a SIP for 

the purposes of demonstrating attainment of the National Ambient Air Quality Standard 

(NAAQS) or reasonable further progress (RFP), but that is not directly enforceable 

against a source. The Urban Forest and Spare The Air programs are the only two 

voluntary measures in this plan.

Numerous scientific studies and research projects have documented the benefits of 

heat island strategies using urban forest expansion programs, and several states are 

exploring the benefits of adopting urban forest strategies into their SIPs. This emerging 

and voluntary control measure proposes one such strategy that is based on the 

selection of trees provided for the expansion of the urban forest to minimize biogenic 

volatile organic compound (BVOC) emissions.

Sacramento Region Urban Forest

The Sacramento region has succeeded in creating a renowned urban forest. Our forest 

evolved over many years, with each generation of our community adding trees that met 

the needs of their day. In earlier years, urban trees were planted for comfort cooling and 

public health benefits. More recently, the Sacramento Municipal Utility District (SMUD) 

has invested millions of dollars in the strategic planting of an energy-saving urban 

forest. Today we have a pressing need to improve the purity of the region’s air. While 

our urban trees make a major contribution to air quality, they were not planted with this 

in mind and so do not do as much as they could.

The regional urban forest is populated by about 7 million trees, composed of over 100 

different species. Each of these tree species can be categorized as low, medium and 

high biogenic volatile organic compound (BVOC) emitting trees. Currently, about 61% of 

the trees are considered low emitting trees, 28% medium and 11% high emitting trees.

Control Strategy to Minimize BVOC Emissions

This control measure proposes a targeted urban forest management program to reduce 

total urban forest BVOC emissions by favoring the planting of low emitting trees rather 

than medium and high emitting trees during the next 10 years. Through a combination 

of community education and governmental policy change over the next 10 years, the 

control measure calls for a minimum of 390,000 low emitting trees to be planted that 

otherwise would have been medium or high emitting trees. Although the duration of the 

project is 10 years, the actual benefit will last many years longer.

Estimated Emission Reductions

The estimated emission reductions from this urban forest development program for the 

Sacramento region are summarized in the following table. The estimated 2018 VOC 

reduction is about 0.8 tpd, but the credited reduction is limited to 0.2 tpd. This is 
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consistent with the EPA policy76 for incorporating emerging and voluntary measures in a 

SIP that limits the amount of emission reductions allowed due to the uncertainty and 

untested nature of the control mechanisms. For total emerging and voluntary measures, 

EPA has adopted a presumptive77 limit of 6 percent of the total amount of emission 

reductions necessary to demonstrate attainment.

Emerging/Voluntary 

Measures

Adoption 

Year

Implement

Year

Emission Reduction* (tpd)

2018

VOC NOX

Urban Forest Development 

Program (SMAQMD-1) 2014 2008-2018 0 - 0.2 ---

*Reductions within 6% limitation of VOC emission reduction needed to achieve attainment and result from 

lower BVOC emitting trees. More detailed documentation of the credited emission reductions is included 

in Appendix C – Proposed Control Measures.

7.14 Regulatory Control Measures

The regulatory control measures proposed in this 8-hour ozone plan are local programs 

that will achieve emission reductions from:

 Stationary/Area Source Control Measures.

7.15 Stationary and Area-wide Source Control Measures

Historically, local air district regulatory control measures have been implemented to 

control emissions from stationary and area-wide type sources. In general, stationary 

sources include non-mobile sources such as power plants, cement plants, and 

manufacturing facilities. Area-wide sources of pollution are those where the emissions 

are spread over a wide area, such as gas stations, house paints, and residential fuel 

combustion. New air district regulatory control measures are being proposed to obtain 

additional emission reductions from specific stationary and area-wide sources. The 

proposed VOC and NOX emission control measures are briefly summarized in the 

following descriptions, along with estimated emission reductions for the future 2018

attainment demonstration year.

There are differences in the commitments for each district. These differences are due to 

one or more of the following reasons. See Appendix H – Reasonably Available Control 

Measures Analysis, for additional details.

1. The costs are too high and/or the emissions benefits of the measure are too low.

 

76 “Incorporating Emerging and Voluntary Measures in a State Implementation Plan (SIP)” (OAQPS, EPA, 

September 2004, p. 9).

77 The limit is presumptive in that EPA believes it may approve measures into a SIP in excess of the 

presumptive 6 percent where a clear and convincing justification is made by the State for a higher limit.
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2. The requirements are already in place.

3. The measure is technically infeasible due to local circumstances.

7.16 VOC Emission Control Measures

Architectural Coatings

This control measure regulates the volatile organic compound (VOC) content in 

coatings applied to residential, commercial, and industrial structures and their 

appurtenances (e.g., general use flats, general use non-flats, and specialty coatings 

such as industrial maintenance coatings, lacquers, floor coatings, roof coatings, stains, 

etc.). The strategy also regulates the sale of coatings within the district by prohibiting 

manufacturers and suppliers of coatings from selling coatings that do not comply with 

the strategy.

Architectural Coatings Category VOC Emission 

Reduction (tpd)

District Measure Adoption 

Year

Implement

Year 2018

SMAQMD-442 2014 2016 0.9

EDCAQMD-215 2013 2015 0.1

FRAQMD-3.15 2014 2014 <0.1

PCAPCD-218 2012 2013 0.2

YSAQMD-2.14 2014 2016 0.2

Total 1.5

Automotive Refinishing

Automotive refinishing coatings are used on motor vehicles and other mobile 

equipment, primarily by auto body repair and paint shops and automotive dealerships.

The main coating categories include primers, color coatings, and clear coatings. VOC 

emissions from the surface coating operations result from the evaporation of the organic 

solvents used in the coatings. These emissions occur in a number of places during the 

operation, including surface preparation and cleanup, application of the coating, drying 

of the parts, and cleanup of the application equipment.

The control measure will lower the VOC emissions by further regulating the VOC 

content in automotive refinishing coatings.
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Automotive Refinishing Category VOC Emission 

Reduction (tpd)

District Measure Adoption

Year

Implement

Year 2018

SMAQMD-459 2011 2012 0.1

FRAQMD-3.19 2016 2017 <0.1

PCAPCD-234 2015 2017 <0.1

YSAQMD-2.26 2008 2009-2010 <0.1

Total 0.2

Degreasing/Solvent Cleaning

Degreasing and solvent cleaning operations are performed by many commercial and 

industrial facilities. Solvents are used for surface preparation for further processing and 

cleaning after manufacturing. Degreasing is widely used by automotive repair and 

maintenance facilities and by electric apparatus and electronic component 

manufacturing or repair, construction trades, printing shops, metal parts and products, 

can coating, and other types of commercial and manufacturing facilities. Solvents are 

also used by coating operations for cleaning of coating application equipment such as 

spray guns and brushes. VOC emissions from general surface preparation and 

degreasing operations result from the evaporation of organic solvents.

This measure primarily proposes to lower the VOC limits in the materials used in 

general cleaning and degreasing operations (which include cold cleaning, vapor 

degreasers, hand wiping, thinning and cleanup solvents).

Degreasing/Solvent Cleaning Category VOC Emission 

Reduction (tpd)

District Measure Adoption 

Year

Implement

Year 2018

FRAQMD-3.14 2011 2011 <0.1

YSAQMD-2.24/2.31 2008 2009 0.7

Total 0.8
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Graphic Arts

VOC emissions from graphic art operations result from the evaporation of organic 

solvents in the inks, fountain solutions, and solvents used in the various types of printing 

processes. These operations produce a wide variety of printed products that include 

books, magazines, newspapers, fliers, posters, and packaging materials. These various 

types of products require that facilities use very specific materials and printing methods.

The different types of printing methods include lithography, flexography, gravure, and 

letterpress.

This proposed control measure for graphic arts operations lowers the current rule 

exemption limit from 400 lbs/month to 60 lbs/month. Additionally, this control measure is 

to revise the various cleaning solvent VOC limits to match the current SMAQMD 

standards.

Graphic Arts Category VOC Emission 

Reduction (tpd)

District Measure Adoption 

Year

Implement

Year 2018

YSAQMD-2.29 2016 2018 Not available

Total ---

Miscellaneous Metal Parts and Products

This category is comprised of VOC emissions from the coating of miscellaneous metal 

parts and products including signs, storage and trash containers, door frames, window 

frames, panels, metal cabinets, caskets and various other metal coating operations.

VOC emissions from the surface coating operations result from the evaporation of the 

organic solvents used in the coatings. These emissions occur in a number of places 

during the operation, including surface preparation and cleanup, application of the 

coating, drying of the parts, and cleanup of the application equipment. This control 

measure will only address the VOC emissions from the coating process. The surface 

preparation and cleanup VOC emissions are addressed under other measures.

Miscellaneous Metal Parts and Products Category VOC Emission 

Reduction (tpd)

District Measure Adoption 

Year

Implement

Year 2018

PCAPCD-CM3 2008 2009 <0.1

Total <0.1
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Natural Gas Production and Processing

There are several natural gas production fields within Sacramento County. Fugitive 

emissions of VOC from natural gas production occur from equipment leaks in valves, 

pumps, compressors, pressure relief devices, flanges, and threaded connections at gas 

wells and associated transmission systems. The proposed control measure would 

establish inspection and repair requirements for leaking components. Emission 

reductions would result from a reduction in the number of leaking components. The 

proposed measure would establish leak inspection frequencies and allowable repair 

periods.

Natural Gas Production and Processing Category

VOC Emission 

Reduction (tpd)

District Measure Adoption 

Year

Implement

Year 2018

SMAQMD-461 2014 2015 0.1

Total 0.1

7.17 NOX Emission Control Measures

Boilers, Steam Generator, and Process Heaters

Boilers and steam generators are used to provide hot water and steam for numerous 

industrial and commercial applications. These applications include space heating, food 

processing, garment laundering, and equipment sterilization. Manufacturing operations 

use process heaters to heat materials or equipment. The equipment burners can be 

fired on solid, liquid or gaseous fuels. The proposed control measure lowers the NOX

emission to a more stringent level. Current technology is widely available to adopt this 

control measure.

Boilers, Steam Generators, and Process Heaters 

Category

NOX Emission 

Reduction (tpd)

District Measure Adoption 

Year

Implement

Year 2018

YSAQMD-2.27 2016 2018 0.2

Total 0.2

IC Engines

Internal combustion (IC) engines are used widely in many different facilities. They can 

be used to drive electric generators, pumps, gas compressors, or blowers. A high 

percentage of the engines are used to provide backup power or electricity in 

emergencies. IC engines use propane, gasoline, natural gas, liquefied petroleum gas, 

diesel or other fuels as their source of energy. The ignition of the fuels converts the 
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energy in the fuel to mechanical energy. NOX is produced during the combustion 

process.

The proposed control measure would establish emission standards for stationary 

engines.

IC Engines Category NOX Emission 

Reduction (tpd)

District Measure Adoption 

Year

Implement

Year 2018

FRAQMD-3.22 2010 2011 <0.1

Total <0.1

Large Water Heaters and Small Boilers

Large water heaters and small boilers are used to provide hot water and steam to a 

variety of different applications, including space heating and food processing. Those 

units are usually fired on gaseous fuels and have burner ratings of less than 1 million 

BTU/hr. In general, units with burner rating under 0.3 million BTU/hr use the draft 

created during the combustion process to transfer heat into the water. Large units (0.3 

million BTU/hr or above) use fans or the natural draft to transfer heat into the heating 

system.

Currently, 75,000 to 1 million BTU/hr units are exempted from the districts’ rule for water 

heaters and boilers. This revised control measure will eliminate the exemption for new 

75,000 to 1 million BTU/hr units.

Large Water Heaters and Small Boilers Category NOX Emission 

Reduction (tpd)

District Measure Adoption

Year

Implement

Year 2018

EDCAQMD-239 2015 2016 <0.1

FRAQMD-3.23 2016 2017 0

PCAPCD-CM2 2015 2017 <0.1

YSAQMD-2.37 2009 2010 0.2

Total 0.2

7.18 Summary of Regional and Local Proposed Emission Reductions

The following Table 7-5 summarizes the list of new regional and local proposed control 

measures and their expected 2018 emission reductions for the Sacramento 

nonattainment area. Emission benefits from these new measures are estimated to 

provide reductions of 2 tons per day of VOC and 1 tons per day of NOX in 2018. Some 
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of these new local measures were adopted by mid -2011, but have not been reflected in 

the inventory.

Table 7-5

Summary of New Regional and Local Proposed Control Measures

Sacramento Nonattainment Area

Control Measure Name 2018 Emission Reductions 

(TPD)

VOC NOX

Regional Non-regulatory Measures

Regional Mobile Incentive Program – On-road <0.1 0.5

Regional Mobile Incentive Program – Off-road <0.1 <0.1

Spare The Air Program <0.1 <0.1

SACOG Transportation Control Measures -- --

Urban Forest Development Program 0 - 0.2 --

Total Regional Non-regulatory Measures* 0.1 0.5

Local Regulatory Measures

Architectural Coating 1.5 --

Automotive Refinishing 0.2 --

Degreasing/Solvent Cleaning 0.7 --

Graphic Arts na --

Miscellaneous Metal Parts and Products <0.1 --

Natural Gas Production and Processing 0.1 --

Boilers, Steam Generator, and Process Heaters -- 0.2

IC Engines -- <0.1

Large Water Heaters and Small Boilers -- 0.2

Total Local Regulatory Measures* 2.6 0.5

Total Reductions* 2.7 1.1

Notes: Numbers are truncated to one decimal place. na = not available

*Total reductions are summed from un-truncated values. See summary table in Appendix C – Proposed Control Measures.
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7.19 Further Study Measures

Further study measures are measures for which insufficient information was available 

during the development of the control strategy to allow the region to commit to them as 

control measures. The adoption of further study measures requires full evaluations of 

emission data, cost effectiveness, technological feasibility, and authority for 

implementation. If the evaluations show that the measures are viable control measures, 

they will be considered for adoption and implementation.

These measures are evaluated qualitatively for environmental impacts in this State 

Implementation Plan and will be evaluated quantitatively for the actual emission benefits 

and feasibility in the future. These further study measures are: 1) Heat Island Mitigation, 

2) Alternative Energy, 3) Energy Efficiency, 4) Gasoline Transfer Phase I/II, 5) 

Lubricants, and 6) Episodic Controls. More detailed information on these measures can 

be found in Appendix C – Proposed Control Measures.

Urban Heat Island

The Urban Heat Island Measure encourages activities that would lower the ambient 

temperature in urban areas, such as lighter, more reflective surface materials, building 

surface and pavements, solar roofing membranes, and increased tree planting. 

Programs to promote use of reflective materials and tree planting could be a required

element for new sources or recommendations through California Environmental Quality 

Act (CEQA) Air Quality Handbook. Sources that promote higher reflective materials or 

tree planting could be eligible for emission credits. The emission credits could be based 

on the type of reflective materials and trees per unit area that meet or exceed the

benchmark.

Alternative Energy

The use of alternative energy in transportation or stationary applications can reduce 

ozone precursors. This measure will look at reductions possible in the stationary sector 

of the region. This source category includes facilities or operations that have VOCcontaining byproducts that can be converted to electric energy by utilizing currently 

available technology or other byproducts such as biomass waste, from which energy 

could also be derived. This measure will also evaluate opportunities to convert green 

waste or other forms of biomass into electricity generation. The electricity produced may 

be used for the source facility or metered and sold to utility companies.

Energy Efficiency

This measure will look at possible sources of emissions in the region that could reduce 

ozone precursors by reducing energy consumption. The region districts will evaluate 

energy efficiency projects and practices that have a demonstrable benefit to air quality
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and examine green certification of energy efficient buildings that utilized green building 

practices.

Gasoline Transfer Phase I/II

This measure seeks to reduce VOC and toxic emissions from gasoline dispensing 

facilities by improving implementation of the Enhanced Vapor Recovery (EVR) 

Regulation. The EVR regulation includes testing and certification procedures to improve 

the performance and specification of Phases I and II vapor recovery systems. This 

measure will evaluate methods to improve the functions of the in-station diagnostic. 

Improvements may include providing earlier warning signal, changing both the warning 

and gross failure alerting ranges, disallowing the use of the reset button, or installing a 

“shut down” sensor or mechanism on the dispenser to stop fueling if the fuel filters are 

blocked and the fueling flow rate drops below the system certification standards. In 

addition, this measure will explore the option to require controls for mobile refuelers if a 

district rule has not established such requirements.

Lubricants

This measure seeks to reduce VOC emissions from the use of lubricants that are 

utilized by different industrial processes. Lubricants with their additives are at least 50 

percent VOC solvents and are believed to emit a significant amount of VOCs. In 

addition, lubricant thinners usually contain toxic chemicals which are classified as 

Hazardous Air Pollutants (HAPs) by the EPA and Toxic Air Contaminants (TACs) by the 

state of California. This measure will look at further reducing source emissions by either 

placing an overall emission limit by source or by limiting VOC content in lubricant 

formulations at the point of sale or use.

Episodic Controls

There are various emission reduction strategies that could potentially be implemented 

on an episodic basis when meteorological conditions would normally result in ozone 

exceedances. This further study measure will evaluate the feasibility of banning or 

reducing the use of a variety of types of equipment on high ozone days such as 

construction equipment, pleasure craft or other recreational vehicles; and lawn and 

landscaping equipment.

7.20 Contingency Measures

In general, contingency measures are control measures that go into effect if planned 

emission controls fail to reach desired goals and targets. Contingency provisions are 

required under sections 172(c)(9) and 182(c)(9) of the Clean Air Act in the event the 

nonattainment area fails to meet a reasonable further progress milestone or attainment 

deadline. Contingency measures are specific additional controls to be implemented 
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automatically without further significant rulemaking activities, such as public hearings or 

legislative review, and without further action by the State or the Administrator (EPA).

Federal guidance78 requires that contingency measures must be adopted to provide 3% 

more emission reductions than needed to meet the reasonable further progress and 

attainment demonstration requirements. The control measure strategy in this plan is 

expected to surpass the amount of emission reductions needed for reasonable further 

progress targets and for attainment by a margin that meets the contingency measures 

requirements. The calculations that demonstrate the anticipated contingency reductions 

are documented in conjunction with the attainment demonstration in Chapter 8 and the 

reasonable further progress demonstration in Chapter 13.

 

78 ”General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990” (57 FR 

13498, April 16, 1992).
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8 ATTAINMENT DEMONSTRATION

8.1 Introduction to Attainment Demonstration

EPA guidance79 states, “A modeled attainment demonstration consists of (a) analyses 

which estimate whether selected emissions reductions will result in ambient 

concentrations that meet the NAAQS, and (b) an identified set of control measures 

which will result in the required emissions reductions.” To meet these requirements, this 

chapter incorporates all the major plan elements from Chapters 5 to 7 (emission 

inventories, modeling, and control measures) to demonstrate attainment by the required 

deadline.

8.2 Attainment Demonstration Requirements

Section 182(c)(2)(A) of the Clean Air Act requires that attainment demonstrations for 

“serious and higher” classified nonattainment areas be based on photochemical grid 

modeling or any other analytical method determined by EPA to be at least as effective. 

In addition, EPA provides recommended guidance80 on how to apply air quality models 

to generate results for preparing 8-hour ozone attainment demonstrations.

EPA regulations also require serious and higher nonattainment areas to meet various 

criteria contained in 40 CFR 51.112 for attainment demonstrations. The demonstration 

criteria include the following:

 A summary of the computations, assumptions, and judgments used to determine the 

level of emission reductions (or reductions in the growth of emissions) that will result 

from the implementation of the control strategy.

 A presentation of emission levels expected to result from implementation of each 

measure of the control strategy.

 A presentation of the air quality levels expected to result from implementation of the 

overall control strategy presented either in tabular form or as an isopleth map 

showing expected maximum pollutant concentrations.

 A description of the air quality models used to project air quality and to evaluate 

control strategies.

8.3 Attainment Demonstration Evaluation

Attainment of the 8-hour ozone NAAQS is evaluated for a 2018 “severe” classification 

scenario, based on modeling results for the peak ozone site (Cool) in the Sacramento 

region. The modeled VOC and NOX emission forecasts for 2018 incorporate growth 

assumptions and the estimated reductions associated with the existing control strategy. 

The photochemical modeling results in Chapter 6 were used to predict the 2018 

 

79 “Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals 

for Ozone, PM2.5, and Regional Haze” (EPA, April 2007, p. 15).

80 Ibid, p. 15-40.
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regional peak ozone design value (88 ppb) and estimate the percent reductions needed 

from the 2018 emission forecasts in order to achieve the federal 8-hour ozone standard.

The combined reductions from adopted local, state, and federal control measures are 

used to assess future 2018 attainment. These include (i) measures adopted since the 

initial regional adoption of this Plan in 2009, and (ii) from proposed control measures 

identified in this Plan that have yet to be adopted or reflected in the current inventory.

The total benefits from all remaining control measure are estimated to be 8 tpd of VOC 

and 1 tpd of NOX in 201881.

The emission reductions from new measures are shown in Table 8-1, lines J and K.

Although it appears that some NOx reductions from ‘remaining measures’ are needed to 

reach the 2018 attainment emissions target (Table 8-1, Line G), one of the measures,

YSAQMD Rule 2.37 for water heaters, has been adopted and approved by EPA (75 FR 

25778) and achieved more than the anticipated emissions benefits expected in 2018. 

That measure is still included as a “remaining measure” because the emissions benefits 

have not yet been reflected in the emissions inventory. Rule 2.37 was expected to 

achieve 0.2 tpd NOx emissions reductions in this plan. The EPA approved Rule 2.37 is 

expected to achieve 0.5 tpd NOx reductions. Therefore, we conclude that the region 

does not rely on new measures to attain by 2018. These remaining measures provide a 

buffer for meeting attainment by 2018.

VOC and NOX Reduction Goals for 2018 

Figure 8-1 contains the ozone and pollutant emission reduction graph, based on 

modeling results, for the peak ozone design value site at Cool in the Sacramento 

region. This diagram shows the pattern of ozone responses to varying combinations in 

domain-wide VOC and NOX emission reductions. There are any number of potential 

VOC and NOX reduction combinations that could provide for attainment. Since the 

ozone design values are truncated to the whole ppb, values below 85 ppb represent 

attainment of the federal 8-hour ozone standard.

The modeling results for the combination of emission reductions from new control 

measures indicate attainment of the federal 8-hour ozone standard (84 ppb) for:

1) the 2018 emission reductions from all new local, regional, state and federal control 

measure committals (11.6% of VOC and 16.3% of NOX, designated at Point A).

2) the 2018 emission reductions from only the new local, regional, state and federal 

control measures adopted by the end of 2008 (3.3% of VOC and 12.5% of NOX, 

designated at Point B).

Additional modeling details and assumptions for assessing the VOC and NOX reduction 

attainment goals are provided in Appendix B – Photochemical Modeling.

 

81 Sum of Expected emission reductions from New Emission Standards for Recreational Boats and 

Expanded Off-Road Recreation Vehicle Emissions Standards (Table 7-1) and Emissions Reductions from 

Local/Regional Control Measures (Page C-5)
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8.4 Attainment Demonstration Conclusions

Attainment of the 1997 federal 8-hour ozone standard is demonstrated for the 2018 

“severe” classification deadline in the Sacramento region as shown in Table 8-1 and the 

graph in Figure 8-1. The total emission reductions from remaining, non-EPA approved, 

measures are not needed for attainment and provide a buffer to ensure the region 

meets the 2018 attainment deadline.
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Figure 8-1

Attainment Demonstration Analysis

Predicted 2018 Regional Peak Ozone Design Value at Cool

Sacramento Nonattainment Area

1. The upper right corner point designates the predicted 2018 peak ozone design value (88 ppb) based 

on the forecasted 2018 planning emissions inventory used in the Plan as adopted in 2009 (without 

new control measures): 121 tpd of VOC and 104 tpd of NOX.

2. The x and y axes represent fractional emissions reductions from the forecasted 2018 planning 

emissions inventory used in the Plan as adopted in 2009.

3. The whole numbers on the graph represent predicted ozone design value concentrations (truncated to 

whole ppb), based on modeling results for fractional VOC and NOX reductions at 5% increments. 

Values below 85 ppb represent attainment of the federal 8-hour ozone standard.

4. Point A identifies the percentage of emission reductions (3.3% VOC and 12.5% NOX from 2018 

emissions projected without new controls) that would have been achieved with the control strategy 

identified in the plan as adopted by local districts in 2009. Point A is below 85 ppb, demonstrating that 

this percentage of reductions would result in attainment of the standard at the Cool monitoring site.

88

87

85

84

82

88

86

85

84

82

88

86

85

83

82

87

86

85

83

82

87

86

85

83

82

A

B

0.80 0.82 0.84 0.86 0.88 0.90 0.92 0.94 0.96 0.98 1.00

VOC

0.80

0.82

0.84

0.86

0.88

0.90

0.92

0.94

0.96

0.98

1.00

NOx

A
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8.5 Summary of Attainment Demonstration

The attainment demonstration for the Sacramento nonattainment area is summarized in 

Table 8-1. The attainment demonstration is based on the combination of emission 

reductions from new VOC and NOX control measures that reduce the peak ozone 

design value to the 1997 federal 8-hour ozone standard (84 ppb), based on modeling 

results.

Table 8-1

Summary of Attainment Demonstration for 8-Hour Ozone NAAQS

2018 “Severe” Classification Scenario

Sacramento Nonattainment Area VOC (tpd) NOX (tpd)

Summary of 2009 Plan Attainment Demonstration

A) 2002 Planning Emissions Inventory 1160.3 196.1

B) 2018 Planning Emissions Inventory with Existing Controls 1121.1 104.1

C) Attainment Emission Reduction in percentage 23.3% 12.5%

D) SIP Emissions Target: Line B × (1 – Line C) 117.1 91.1

E Percentage Emission Reduction Required for Attainment: 

( 1 – (Line D ÷ Line A) ) × 100% 27.0% 53.6%

Revised Emissions Targets

F) Updated 2002 Inventory 3146.7 164.8

G) Updated SIP Emissions Target: Line F × ( 1 – Line E ) 107.1 76.5

Revised Attainment Demonstration

H) Updated 2018 Inventory 397.7 73.9

I Motor Vehicle Emissions Budgets Safety Margin 41 3

J) Emission Reductions in 2018 from Remaining Regional/Local Control 

Measures 5,7 2.7 1.1

K Emissions Reductions in 2018 from Remaining State/Federal Control 

Measures 6,7 5.7 0.3

L) Total Emissions in 2018 with All Remaining Controls:

( Line H + Line I - Line J – Line K )

90.3 75.5

M) Is Attainment Demonstrated? (Is Line L ≤ Line G?) Yes

1. The 2009 inventory is shown in Appendix A8.

2. The percent emission reduction targets for attainment are based on modeling results. Figure 8-1 

Point A.

3. Chapter 5. Tables 5-2 and 5-3 include ERCs (ERC details are in Tables 5-4 and 5-5).

4. Chapter 11 Table 11-1

5. Appendix C, Table of Emission Reductions by Air District, Page C-5.

6. Chapter 7. Table 7-2, sum of expected emission reductions from New Emission Standards for 

Recreational Boats and Expanded Off-Road Rec. Vehicle Emission Standards.

7. These reductions provide a buffer for meeting attainment targets.
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Attainment Demonstration

Page 8-6

8.6 Attainment Demonstration Contingency Measures Requirement

Federal guidance requires that sufficient contingency measures in the plan should be 

adopted to provide a 3% emission reduction beyond what is needed for the attainment 

demonstration. The expected additional emission reduction benefits achieved from 

existing control programs meet the attainment contingency requirement in 2019. More 

detailed information and documentation on the 2019 emissions inventory are provided 

in Appendix A – Emissions Inventory.

The calculations of the attainment contingency measures reductions for 2019 are 

provided in Table 8-2. The combined VOC and NOX reductions in 2019 exceed the 3% 

needed to meet the attainment contingency requirement.

Table 8-2

Attainment Contingency Measures Reductions

Sacramento Nonattainment Area

Revised Inventory (adjusted CEPAM 2012) (tpd) VOC NOX

A. Updated SIP Emission Target 1107.1 76.5

B. Updated 2019 Emissions 299.8 74.4

2019 Total Reductions (tpd) VOC NOX

C. 2019 Reductions From Emission Target 

[Line A – Line B] 7.4 2.2

D. Percent Reduction from SIP Emission Target 

[Line C ÷ Line A] × 100% 6.9% 2.8%

Conclusion:

The combined VOC and NOX reductions 

total 9.7%, which exceeds the 3% 

attainment contingency requirement.

1. Table 8-1 Line G.

2. Appendix A, Table A7-1. Plus the MVEB safety margin from Table 8-1 Line I. Total ERCs (rounded up) listed in

Tables 5-4 and 5-5 are included in the 2019 inventory.
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Transport Analysis

Page 9-1

9 TRANSPORT ANALYSIS

9.1 Introduction to Pollutant Transport

The air quality in the Sacramento region can be impacted by pollutant transport from the 

San Francisco Bay Area. Delta breezes carry air pollutants from coastal Bay Area 

emission sources downwind to the inland areas of the Sacramento region, and these 

pollutants may contribute to ozone formation during the same day or the following days.

The California Air Resources Board has determined that the relative impact from this 

Bay Area transport can be considered overwhelming, significant, or inconsequential on 

various days82, depending on meteorological conditions. CARB has also made findings 

that pollutant transport from the San Joaquin Valley can have significant or 

inconsequential impact83 on air quality in the Sacramento region.

In addition, pollutant transport from the Sacramento region can potentially impact the air 

quality in other regions under certain meteorological conditions. For example, CARB 

analyses have determined that ozone violations at the Grass Valley monitoring station 

in Nevada County are considered to be overwhelmingly due to transport from the 

Sacramento region84.

This chapter discusses various interbasin transport issues and modeling assumptions 

regarding transported air pollutants.

9.2 Interbasin Transport Issues

There are many different issues involving interbasin transport of air pollutants. First, air 

pollutant transport is evaluated in order to get a more complete picture of how ozone is 

formed in the Sacramento region. Depending on meteorological conditions, the amount 

of transport from outside the nonattainment area can vary from day to day.

Understanding the impacts of transport can be an important factor in predicting future 

attainment of the ozone standard in the Sacramento region. For example, if a region’s 

ozone problem is significantly caused by outside pollutant transport, then a local 

emission control strategy may not achieve its goal.

Another issue is that air pollutant transport is difficult to assess and can involve many 

different complex methodologies with varying degrees of limitations and uncertainty. For 

example, surface wind flow studies using ambient meteorological and air quality 

monitoring data can reveal general directional and temporal potential for transport and 

qualitative air pollution impacts. However, specific quantitative impacts on downwind 

ozone formation may still be undetermined and carryover effects may be unaccounted 

for. Photochemical grid modeling studies can quantify a more precise transport 

contribution to downwind ozone and take carryover into account, but they may only be 

 

82 California Air Resources Board, “Ozone Transport: 2001 Review” (April 2001).

83 Ibid.

84 Ibid.
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representative of a specific ozone episode of several days and subject to various 

modeling performance uncertainties.

In addition, other issues pertaining to transport assessment include: 1) uncertainties in 

transport occurring from aloft layers85, 2) potentially different assumptions in future 

emission reduction strategies in upwind air basins, 3) transport from the Sacramento 

region to other downwind areas, and 4) emissions transport due to motor vehicles 

traveling between air basins.

9.3 EPA Rules and Regulations on Intrastate Transport

The Federal 8-hour ozone implementation rules

86 state that intrastate transport could be 

considered by EPA and States in determining the attainment date that is as expeditious 

as practicable for nonattainment areas. However, if the date were later than allowed for 

the area’s classification, the State would need to request a bump-up of the area to a 

higher classification for that date to be approved. In identifying the appropriate 

attainment date for an area, the State should consider measures to address intrastate 

transport of pollution from sources within its jurisdiction.

9.4 Attainment Assumptions of Domain-wide Reductions

Transported pollutants from upwind areas can contribute to the ozone problem further 

downwind across geographic air basins. The photochemical grid modeling study 

includes the northern and central regions of California in the modeling domain (see 

Chapter 6 – Air Quality Modeling Analysis). This extensive air quality model was used to 

address and account for air pollutant transport impacts among the San Francisco Bay 

Area, San Joaquin Valley, Sacramento Valley, and Mountain Counties air basins.

States are responsible for submitting SIPs for all areas of their State and need to 

demonstrate attainment in all areas addressing intrastate transport where appropriate.

CARB modeling for the attainment demonstration for the Sacramento nonattainment 

area used domain-wide emission reductions to characterize future ozone reductions at 

peak ozone monitoring stations. Therefore, for our area to attain, reductions in 

forecasted emissions necessary and committed to in Sacramento must also be 

achieved in the areas that significantly impact the region. In other words, the attainment 

demonstration for the Sacramento nonattainment area is predicated on the San 

Francisco Bay Area and the San Joaquin Valley also achieving an equivalent additional 

percent reduction of VOC and NOX emissions in their forecasted 2018 inventory.

The reductions could come from either state or upwind regions’ local measures, but we 

understand that CARB has committed to address the reduction requirement by 

implementing the new state measures statewide. The CARB attainment demonstration 

for Sacramento has not quantified state measure benefits in the Bay Area or the impact 

 

85 Aloft layers are the layers above the surface inversion layer.

86 “Final Rule to Implement the 8-Hour Ozone National Ambient Air Quality Standard – Phase 2” (Federal 

Register, November 29, 2005, p. 71623-71624).
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of Bay Area transport. Because the measures identified in CARB’s 2007 Statewide SIP 

Strategy87 achieve 9% VOC and 14% NOX reductions from the 2018 emission inventory 

forecasts for the Sacramento region, it is likely that the state measures will achieve 

similar reductions in the Bay Area and San Joaquin Valley.

Regarding the ozone violations in Nevada County, emission reduction strategies in the 

Sacramento region will benefit their efforts to attain the federal ozone standards. CARB 

modeling results predict that future ozone reductions at the Grass Valley monitoring 

station could achieve the 1997 federal 8-hour ozone standard by 2018. Ultimately, 

CARB is responsible for ensuring that Nevada County meets its federal attainment 

requirements.

 

87 CARB. Air Resources Board’s Proposed State Strategy for California’s 2007 State Implementation 

Plan. CA: California Air Resources Board, Sacramento, CA [2007.] Web 18 April 2013,

< http://www.arb.ca.gov/planning/sip/2007sip/2007sip.htm#April26>
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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Weight-of-Evidence Determination

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10 WEIGHT-OF-EVIDENCE DETERMINATION

10.1 Introduction to Weight-of-Evidence

Air quality computer models attempt to represent or simulate complex physical and 

chemical phenomena occurring in the atmosphere, based on the best available 

information. Photochemical models are used to predict future ozone concentrations and 

quantify VOC and NOX emission reduction targets for meeting the ambient ozone 

standard. As mentioned at the end of Chapter 6, air quality modeling uncertainties can 

arise due to: 1) the model’s simplification of atmospheric processes, 2) inaccuracies 

from meteorological, emissions, and other input data bases, and 3) limitations in the 

assumptions and methodologies for forecasting future emissions, meteorological 

conditions, and ozone design value concentrations.

Attainment demonstrations based on photochemical modeling can be strengthened by 

supplemental evidence from additional modeling analyses and from considering 

modeling outputs other than the attainment test results. More diverse non-modeling and 

observational methods analyzing air quality, meteorological, and emissions data can 

also be used to corroborate the modeling predictions.

This chapter summarizes the recommended requirements and methodology for 

preparing a weight-of-evidence (WOE) determination and the WOE analysis performed 

by the California Air Resource Board staff for the region. The CARB weight-of-evidence 

assessment indicates that the ozone attainment demonstration is likely to be achieved 

by the mandated deadline. More detailed information on the weight-of-evidence 

techniques and evaluations are provided in Appendix E – Weight-of-Evidence Analyses.

10.2 Weight-of-Evidence Requirements

EPA guidance88 requires districts (or the state) to conduct a comprehensive weight-ofevidence analysis to support the modeled attainment demonstration. The amount of 

supporting material needed depends on how close the attainment modeling 

demonstration is to meeting the 8-hour ozone standard (84 ppb) at all monitors. For 

example, a limited amount of basic supplemental analyses is required if the predicted 

future ozone design value concentration is less than 82 ppb at all monitors. However, if 

future design values are closer to the NAAQS, more rigorous analyses must be 

conducted.

Corroborative analyses can include the following:89

 Modeling performance evaluation and assessment of uncertainty, such as:

- accuracy in simulating ozone formation

- reliability of modeling data bases

- confidence in forecasting methodologies

 

88 “Guidance on the Use of Models and Other Analyses for Demonstrating Attainment of Air Quality Goals 

for Ozone, PM2.5, and Regional Haze” (EPA, April 2007, p. 98-109).

89 Ibid.
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 Other modeling results and characteristics, such as:

- how close predicted future ozone results are to attainment

- number of years projected to attainment year

- representativeness of modeling episodes

 Trends in ambient air quality and ozone precursor emissions, such as:

- assessment of monitored ozone trends

- assessment of monitored ambient ozone precursor pollutant trends

- assessment of VOC and NOX emission trends

 Observational methods to assess control strategies, such as:

- using receptor models to verify emission source categories causing ambient 

precursor pollutants

- using ambient indicator species/ratios to evaluate sensitivity of ozone 

formation to precursor pollutants

- review success of implementing SIP committal controls

10.3 Methodology for Applying Weight-of-Evidence Analyses

EPA guidance90 states, “A weight-of-evidence determination examines results from a 

diverse set of additional analyses, including the outcome of the primary attainment test, 

and attempts to summarize the results into an aggregate conclusion” with respect to the 

attainment demonstration. “Each analysis is weighed qualitatively, depending on: 1) the 

capacity of the analysis to address the adequacy of a strategy and 2) the technical 

credibility of the analysis.”

The weight-of-evidence end product is a document which describes the following:

 Analyses performed,

 Data bases used,

 Key assumptions and outcomes of each analysis, and

 Rationale for concluding that the aggregate evidence supports a conclusion 

regarding whether the area will or will not attain the ozone standard, which may 

differ from the modeled attainment test.

10.4 Summary of CARB Weight-of-Evidence Analyses91

Photochemical modeling results indicate that reducing NOX emissions will be the most 

effective strategy for bringing the Sacramento Metro Area92 into attainment. These 

reductions will not be in place by the 2013 deadline. However, they will be implemented 

by 2018. Therefore, districts in the Sacramento Metro Area have approved 

reclassification, and ARB has requested that U.S. EPA reclassify the Sacramento Metro 

Area as Severe-15, with a required attainment date of June 15, 2019.

 

90 Ibid.

91 This section was not updated. See Chapter 4, 8-Hour Ozone Air Quality Trends, for updated trend 

information.

92 Sacramento Metro Area is considered the same as the Sacramento Federal Nonattainment Area.
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The ARB staff’s modeling results indicate that NOX emissions reductions will be critical 

for bringing sites in the Sacramento Metro Area into attainment. Given the timeframe 

over which these reductions are expected to occur, the Sacramento Metro Area should 

be attainment by June 15, 2019, with a 10 percent or more reduction in forecasted NOX

emissions. Based on modeling, as well as supporting analyses included in this WOE 

evaluation, attainment by 2019 is anticipated because of the following factors:

 Since 1999, the number of areawide exceedance days has decreased a little

more than 10 percent. The maximum concentration and design value show 

more modest reductions, with decreases of about 10 and 5 percent, 

respectively, from 1999 to 2006. Because these are areawide numbers, they 

reflect the “worst case” sites. Although 2007 data show a slightly higher 

maximum concentration and a design value comparable with 2006, they show 

the number of areawide exceedance days at an all-time low of 16 days for the 

entire year.

 While the amount of progress varies on a subregional basis, there has been a 

substantial reduction in the number of exceedance days in the western 

subregion. Since 1999, exceedance days decreased 25 percent, and all sites 

in this subregion now attain the federal 8-hour ozone standard.

 Between 1999 and 2006, the central subregion shows a 10 percent decrease 

in the three-year average of exceedance days at all sites but Folsom, which 

shows only a slight reduction in days. Although progress at Folsom appears 

to have slowed over the last several years, the central subregion has 

demonstrated long-term progress. Sites with long-term data, including 

Folsom, show a 35 to 50 percent decrease in exceedance days since 1990, 

based on three-year averages. The decrease in design values has been more 

modest, averaging about 5 percent since 1990.

 Although sites in the eastern subregion still have some of the highest ozone 

concentrations, the three-year average of exceedance days at Cool, the worst 

site in this area, decreased about 15 percent between 1999 and 2006. Other 

sites in the subregion showed little change in the average number of 

exceedance days between 1999 and 2006.

 During the late-1990s, the ozone problem was more widespread throughout 

the Sacramento Metro Area. Since then, all areas have improved, although at 

differing rates. All of the western subregion and the easternmost portion of the 

eastern region now meet the federal standard. The ozone problem is now 

confined to the central subregion and the more urbanized portions of the 

eastern subregion. However, even at the worst sites in these subregions 

(Cool and Folsom), 60 to 65 percent of the days during the 2006 ozone 

season were below the more stringent State 8-hour ozone standard.
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Weight-of-Evidence Determination

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 Ozone indicator values for many sites in the Sacramento Metro Area were 

higher for 2005, 2006, and 2007 than for 2004. However, the 2004 values 

were uncharacteristically low. When compared with values for 2002 and 

2003, the values for 2005 through 2007 are generally lower, indicating 

progress. The Sacramento Metro Area is much closer to attainment than 

other areas of the State, such as the South Coast and San Joaquin Valley air 

basins. Because the Sacramento Metro Area values are closer to the 

standard, small variations in meteorology can result in relatively large

year-to-year changes in the trends. These variations can make it difficult to 

interpret the trends. However, in the Sacramento Metro Area, it appears there 

has been overall improvement, despite this variability.

 Analyses suggest that recent ozone improvements are linked to emissions 

reductions. The decline in the number of exceedance days relative to the 

number of days with a high potential for ozone formation indicates that the 

modest improvements in ozone over the last few years were related to 

emissions reductions rather than favorable meteorological conditions. A more 

detailed adjustment of ozone trends for the annual mean of the Top 30 

produced similar results. Results of these analyses also indicate that 

increasingly adverse meteorological conditions are now needed to create 

ozone levels exceeding the federal 8-hour standard.

 Estimated ROG and NOX emissions trends, as well as ambient 

measurements, indicate reductions in both precursors since the mid-1990s.

These reductions have resulted in modest ozone improvements. Emissions 

estimates indicate a continuing decline in ROG and NOX emissions. However, 

photochemical modeling results show that NOX reductions will be critical to 

attainment. As a result, a control strategy relying on a 10 percent or more 

reduction in NOX emissions is proposed as the most efficient path to 

attainment by June 15, 2019.

 Photochemical modeling results show a design value of less than 0.085 ppm 

with proposed new controls for the Sacramento Metro Area by the end of 

2018. Many sites will reach attainment before this date. Coupled with the 

analyses completed for the WOE, it is reasonable to conclude that the entire 

Sacramento Metro Area will reach attainment within this timeframe, consistent 

with the June 15, 2019, attainment deadline.

Taken together, all of these factors indicate that the Sacramento Metro Area can expect 

to attain the federal 8-hour ozone standard by June 15, 2019, the required attainment 

date for a Severe-15 ozone nonattainment area.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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Transportation Conformity and Emission Budgets

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11 TRANSPORTATION CONFORMITY AND EMISSION BUDGETS

11.1 Introduction to Transportation Conformity

Transportation conformity is the federal regulatory procedure for linking and 

coordinating the transportation and air quality planning processes. Under the federal 

Clean Air Act, federal agencies may not approve or fund transportation plans and 

projects unless they are consistent with state air quality implementation plans (SIPs).

Conformity with the SIP requires that transportation activities not cause new air quality 

violations, worsen existing violations, or delay timely attainment of the national ambient 

air quality standards (NAAQS). The quantification and comparison of on-road motor 

vehicle emissions is the method for determining transportation conformity between air 

quality and transportation planning.

This chapter summarizes principal transportation conformity requirements, and 

proposes new motor vehicle emissions budgets (MVEB).

11.2 Transportation Conformity Requirements

The CAA states that no federal department engage in, support in any way or provide 

financial assistance for or license or approve any activity that does not conform to the 

State Implementation Plan (SIP). (42 USC 7506) To implement this requirement, EPA 

established the Transportation Conformity Rule (40 CFR 93). This Rule:

 Establishes criteria and procedures for determining whether long-range 

metropolitan transportation plans (MTPs), short-range metropolitan transportation 

improvement programs (MTIPs), and projects conform to the SIP.

 Ensures that transportation plans and projects are consistent with the applicable 

SIP, such that associated transportation emissions are less than or equal to motor 

vehicle emissions budgets established for demonstrating reasonable further 

progress, attainment or maintenance of health-based air quality standards.

 Ensures that transportation plans, programs, and other individual projects do not 

cause new air quality violations, exacerbate existing ones, or delay attainment of air 

quality standards.

11.3 Purpose of the Motor Vehicle Emissions Budget

The motor vehicle emissions budget is the total allowable emissions allocated to onroad motor vehicles in the submitted or approved SIP revision or maintenance plan for 

reasonable further progress milestones or demonstrating attainment or maintenance of 

the NAAQS. (40 CFR 93.101)

Transportation conformity determinations are accomplished by comparing the motor 

vehicle emissions associated with MTPs and MTIPs with the motor vehicle emissions 

budgets established in the SIP for each attainment, milestone, or transportation 

planning year. If the emissions associated with implementation of the MTP and/or MTIP 
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

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are less than or equal to the budgets established in the SIP, a conformity determination 

can be made.

In this SIP, an emission budget is established for both VOC and NOX for two reasons:

1. Both VOC and NOX are ozone precursors, and reductions of both pollutants are 

needed to demonstrate attainment of the ozone standards, and

2. The reasonable further progress demonstration relies on NOX substitution to meet 

the required goals.

This ozone plan proposes to update the allowable motor vehicle emissions budgets that 

SACOG must use to demonstrate that projected regional motor vehicle emissions with 

all of the new transportation projects will conform to the levels established in the SIP.

11.4 Latest Planning Assumptions

The current and forecasted vehicle miles traveled (VMT) are from SACOG-supplied 

activity data (submitted to ARB October 2012)

93 based on transportation modeling for 

the Sacramento region and recent amendments to the Metropolitan Transportation 

Improvement Plan (2013/16 MTIP)

94

, which received federal approval on December 14, 

2012. In addition, the vehicle activity levels for the eastern part of Solano County in the 

Sacramento nonattainment area are based on MTP data from the Bay Area 

Metropolitan Transportation Commission (submitted to ARB November 2012).

11.5 SACOG’s Blueprint and MTP/SCS 2035

Over the past several years, the Sacramento region has embarked on a process of 

defining and implementing a new, higher density, land use pattern which reduces 

congestion, encroachment on open space, average vehicle miles traveled per 

household and air pollutants. The program, called Blueprint, was initiated by SACOG 

with the goal of reducing traffic congestion in the future metropolitan transportation 

plans.

In December 2004, Blueprint smart growth principles and a 2050 growth scenario were 

approved by SACOG95 to achieve the following objectives:

1. Provide a variety of transportation choices

2. Offer housing choices

3. Take advantage of compact development

4. Use existing assets

5. Increase mixed land use

 

93 SACOG travel data transmittal e-mails to ARB and SMAQMD dated October 10, 2012 and November 

30, 2012 respectively.

94 Final 2013/16 Metropolitan Transportation Improvement Program (MTIP), Amendment #1 to the 

MTP/SCS 2035, and Air Quality Conformity Analysis. (August 16, 2012), FHWA approval December 

14, 2012.

95 http://www.sacog.org/regionalfunding/betterways.pdf
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6. Encourage natural resource conservation

7. Ensure distinctive, attractive communities with quality design

The region then began the more detailed planning efforts for the long range 

Metropolitan Transportation Plan for 2035 (MTP2035). SACOG works with local 

jurisdictions, CalTrans, and transportation and planning agencies to define interim land 

use allocations and specific transportation project needs. Federal MTP guidelines 

require that the land use allocations represent what is most likely to be built. Therefore, 

the specific Blueprint smart growth policies affect land use allocations only to the extent 

that the local jurisdictions and SACOG are able to demonstrate that the policies will 

actually be implemented.

Since the last MTP, California adopted Senate Bill 375, which requires a Sustainable 

Communities Strategy, to be added to transportation plans across the state. As a result, 

the region adopted on April 19, 2012, the Metropolitan Transportation Plan/Sustainable 

Communities Strategy (2012 MTP/SCS). This is a long-range plan for transportation 

built on the Blueprint concept and replaced MTP2035

Updated activity data based on the 2013/16 MTIP96 were used in setting the baseline 

projections for the motor vehicle inventory. While the Blueprint principles affect these 

baseline projections, Blueprint is not included in this plan as a transportation control 

measure.

SACOG’s Transportation Model97

The transportation analysis for the 2013/16 MTIP relied on the latest planning 

assumptions and SACOG’s new regional travel demand forecasting model, SACSIM.98

The SACSIM model was used to estimate future traffic volumes and public transit 

ridership in the 6-county Sacramento region. SACSIM incorporates an “activity-based” 

travel model which simulates the population of households allocated to parcels and 

creates a one-day activity and trip travel schedule for each person in the population.

The activity and travel schedule are sensitive to transportation network accessibility and 

a variety of demographic and land use variables. SACSIM also incorporates a mode 

choice model which determines how each travel destination is reached.

The network traffic assignment models load the trips onto the network, resulting in 

vehicle miles traveled at four time intervals (AM peak, midday, PM peak, and 

evening/early morning) and speed within each time period. To develop the travel 

 

96 Final 2013/16 Metropolitan Transportation Improvement Program (MTIP), Amendment #1 to the 

MTP/SCS 2035, and Air Quality Conformity Analysis. (August 16, 2012), FHWA approval December 

14, 2012.

97 SACOG’s transportation model description and results provided by SACOG’s Gordon Garry e-mail to 

SMAQMD (5-28-08).

98 Bradley, M.A., J.L. Bowman and B. Griesenbeck. “Development and application of the SACSIM 

activity-based model system,” submitted for presentation at the 11th World Conference on Transport 

Research, Berkeley, California. June 2007.
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forecasting model, information on the characteristics and constraints of the 

transportation system and residents’ travel survey data were collected. The SACSIM 

travel outputs were compared to actual base year data to be able to demonstrate 

adequate model performance results.

SACOG used the SACSIM travel demand model to forecast average weekday travel 

patterns for several future years, based on given assumptions about expected future 

population and employment projections,99 land use allocations, and transportation 

system improvements and changes contained in the 2013/16 MTIP100The results of the 

travel model predicted that growth in vehicle trips and growth in vehicle miles traveled 

would be slightly lower than the population growth rate for the Sacramento region 

through 2035.

11.6 Proposed New Motor Vehicle Emissions Budgets

To reflect the updated motor vehicle emission forecasts, the Sacramento Regional 8-

Hour Ozone Attainment and Reasonable Further Progress Plan includes new 

transportation conformity budgets for the, 2014, and 2017 RFP milestone years, and the 

2018 attainment analysis year, listed in Table 11-1. The proposed budgets incorporate: 

1) the recent on-road motor vehicle emission inventory factors of EMFAC2011 

(described in Section 5.3.3), 2) updated travel activity data from SACOG’s 2013/16 

MTIP101 and MTC’s Plan Bay Area Preferred Land Use Scenario/Transportation 

Investment Strategy (May 11, 2012)102, based on the new SACSIM transportation 

modeling system, and 3) latest regional and state control strategies.

Table 11-1

Proposed New Motor Vehicle Emission Budgets

Sacramento Nonattainment Area

NOX VOC

2014 2017 2018 2014 2017 2018

ARB Inventories for Conformity (Tons per 

Day) 46 37 34 21 17 16

Safety Margin 3 2 3 2 1 1

Budgets 49 39 37 23 18 17

*All motor vehicle emission budget years include regional incentive benefits.

 

99 SACOG Board of Directors (September 2007) approved 2013 and 2018 housing and employment 

allocations based on July 2007 DOF projections.

100 Final 2013/16 Metropolitan Transportation Improvement Program (MTIP), Amendment #1 to the 

MTP/SCS 2035, and Air Quality Conformity Analysis. (August 16, 2012) FHWA approved on 

December 14, 2012.

101 Ibid.

102 Joint MTC Planning/ABAG Administrative Committees, Plan Bay Area Preferred Land Use and 

Transportation Investment Strategy. Oakland, CA: Bay Area Metropolitan Transportation 

Commission. [May 2012.]
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Although the regional and local commitment is to the "total emission reductions," for 

purposes of establishing motor vehicle emissions budgets for transportation conformity, 

an explicit commitment is made to the reductions associated with the on-road mobile 

source incentive program in each of the milestone years. These external adjustments 

for certain proposed State measures and local control measures are documented in 

Appendix F – Motor Vehicle Emissions Budgets and VMT Offset demonstration. 

Additionally, the transportation budgets incorporate a “safety margin.”

103 These 

transportation budgets decline significantly from 2014 through 2018, which will ensure 

continued progress towards attainment of the 8-hour ozone standards. As required by 

40CFR93.105, the regional air districts consulted with the metropolitan planning 

organizations, state agencies, Department of Transportation and the U.S. 

Environmental Protection Agency during development of the MVEBs proposed in this 

Plan Revision. On December 11, 2012, a meeting of SACOG’s Regional Planning 

Partnership (RPP)104 was held to review and recommend for adoption of the MVEBs. By 

a consensus vote, members of RPP approved that the proposed MVEBs to be included 

in the Plan revision. The proposed MVEBs were also presented to the Land Use and 

Natural Resources Committee of the SACOG Board on February 7, 2013.

11.7 Motor Vehicle Emissions Budget Approval Process

EPA can make an adequacy finding on new 8-hour motor vehicle emissions budgets

prior to their approval of a SIP revision plan. This adequacy review process is subject to 

public participation and review requirements pursuant to 40 CFR 93.118(f). This 

adequacy process is intended to expedite the use of conformity budgets to protect air 

quality.

US EPA determined the motor vehicle emissions budgets for 2014, 2017, to be 

adequate and found the budget for 2018 inadequate on July 28, 2009. The budgets in 

this plan replace the prior budgets105.

If determined to be adequate for transportation conformity purposes by EPA, future 

transportation plans will need to conform to these new motor vehicle emissions budgets.

The Metropolitan Planning Organizations, SACOG and MTC, must ensure that the 

aggregate transportation emissions in the region stay below these levels when 

approving new metropolitan transportation plans and transportation improvement 

programs, even if the mix of projects changes or growth increases. Following EPA 

action, these new 8-hour MVEBs will remain in effect until other budgets are found 

adequate or approved by EPA.

 

103 40 CFR 93.101 and 40 CFR 93.124.

104 SACOG. Regional Planning Partnership December 11, 2012 Meeting Agenda Item 6: Proposed 

Update to Sacramento Ozone Pre-Cursor Emissions Budgets. Sacramento Area Council of 

Governments, Sacramento, CA. [December 11, 2012.]

105 Federal Register Volume 74 No. 143 p.37210, 07/28/2009.
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11.8 Vehicle Miles Traveled Offset (VMT Offset)

Section 182(d)(1)(A) of the federal Clean Air Act applies to areas classified as severe or 

extreme nonattainment of the National Ambient Air Quality Standard (NAAQS) for 

ozone. The Sacramento Federal Ozone Nonattainment Area is currently designated as 

Severe-15, (75FR24409) and is subject to the requirement to offset any growth in 

emissions resulting from an increase in vehicle miles travelled. A detailed VMT offset 

demonstration was prepared by California Air Resources Board and is included in 

Appendix F – Motor Vehicle Emission Budgets and VMT Offset Demonstration as part 

of the 2013 revision to the Sacramento Regional 8-Hour Ozone Attainment and 

Reasonable Further Progress Plan. The analysis shows there are sufficient 

transportation control strategies and TCMs to offset the emissions increase due to 

growth in VMT and demonstrates compliance with the requirements of Section 

182(d)(1)(A) of the federal Clean Air Act.
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12 GENERAL CONFORMITY

12.1 Introduction to General Conformity

General conformity is the federal regulatory process for preventing major federal 

actions106 or projects from interfering with air quality planning goals. Conformity 

provisions ensure that federal funding and approval are given only to those activities

and projects that are consistent with state air quality implementation plans (SIPs).

Conformity with the SIP means that major federal actions will not cause new air quality 

violations, worsen existing violations, or delay timely attainment of the national ambient 

air quality standards (NAAQS).

Current federal rules require that federal agencies use the emissions inventory from an

approved SIP’s attainment or maintenance demonstration to support a conformity 

determination. The 1994 SIP is the most recent attainment plan for the Sacramento 

region that may be used to assess general conformity. The emissions inventory in this 

8-hour ozone attainment plan will replace the old 1994 SIP emissions inventory for 

general conformity purposes.

This chapter summarizes basic general conformity requirements and emissions criteria 

for demonstrating general conformity. In addition, a specific inventory for airport 

emissions is provided in this chapter for the potential general conformity analysis of 

future airport expansions.

12.2 General Conformity Requirements

The Clean Air Act (CAA) states that no federal department may engage in, support in 

any way or provide financial assistance for or license or approve any activity that does 

not conform to an approved SIP. (42 USC 7506)

The EPA promulgated the conformity regulations for general federal actions (40 CFR 51 

subpart W and 40 CFR 93 subpart B) pursuant to section 176(c) of the Clean Air Act.

The “General Conformity” Rule sets forth the requirements a federal agency must 

comply with to make a conformity determination. General conformity requires that 

federal agencies and departments not support or approve an action that does any of the 

following:

 Causes or contributes to new violations of any NAAQS in an area;

 Increases the frequency or severity of an existing violation of any NAAQS; or

 Delays timely attainment of any NAAQS, required interim emission reduction, or 

other milestones.

 

106 Federal actions are defined as any activity engaged in by a department, agency, or instrumentality of 

the Federal government, or any activity that they support, fund, license, permit, or approve, other than 

activities related to transportation plans, programs, and projects that are applicable to transportation 

conformity requirements. (40 CFR 93.152)
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12.3 Types of Federal Actions Subject to General Conformity Requirements

Examples of general federal actions that may require a conformity determination 

include, but are not limited to, the following: leasing of federal land, private construction 

on federal land, reuse of military bases, airport construction and expansions, and 

construction of federal office buildings.

General conformity requirements apply only if federal actions satisfy one of the following 

two conditions: (40 CFR 93.153)

 The action’s direct and indirect emissions have the potential to exceed the de 

minimus threshold levels established for criteria pollutants in the rule. For a severe

nonattainment area, the threshold level is 25 tons per year of VOC or NOX.

 The action’s direct and indirect emissions of any criteria pollutant represent 10% or 

more of a nonattainment or maintenance area’s total emissions inventory for that 

pollutant. For the nonattainment area, 10% of the total 2002 VOC emission inventory 

is 16 tons per day (or about 5,700 tons per year), and 10% of the total 2002 NOX

emission inventory is 19 tons per day (or about 6,900 tons per year).

Direct emissions of a criteria pollutant or its precursors107 are emissions that are caused 

or created by the federal action, and occur at the same time and place as the action.

Indirect emissions are reasonably foreseeable emissions that are further removed from 

the federal action in time and/or distance, and can be practicably controlled by the 

federal agency due to a continuing program responsibility. (40 CFR 93.152) A federal 

agency can indirectly control emissions by placing conditions on federal approval or 

federal funding. An example would be controlling emissions by limiting the size of a 

parking facility or by making employee trip reduction requirements.

108

12.4 Emissions Criteria for Demonstrating General Conformity

To meet the conformity determination emissions criteria, the total of direct and indirect 

emissions from a federal action must meet all relevant requirements and milestones 

contained in the applicable SIP (40 CFR 93.158(c)), and must meet other specified 

requirements, such as:

 For any criteria pollutant, the total of direct and indirect emissions from the action 

must be specifically identified and accounted for in the applicable SIP’s attainment 

or maintenance demonstration (40 CFR 93.158(a)(1)); or

 For ozone, the total of direct and indirect emissions from the action must be fully 

offset within the same nonattainment (or maintenance) area through a revision to 

the applicable SIP or a similarly enforceable emissions control measure in the SIP 

(40 CFR 93.158(a)(2)); or

 

107 Precursors for ozone include NOX and VOC pollutants (40 CFR 93.152).

108 “General Conformity Guidance: Questions and Answers” (OAQPS, EPA, dated July 13, 1994), p. 13.
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 For ozone, CARB must make a finding that the total of direct and indirect emissions 

from the action will result in a level of emissions that, together with all other 

emissions in the nonattainment (or maintenance) area, will not exceed the 

emissions inventory specified in the applicable SIP (40 CFR 93.158(a)(5)(i)(A)); or

 For ozone, CARB must make a finding that the total of direct and indirect emissions 

from the action will result in a level of emissions that, together with all other 

emissions in the nonattainment (or maintenance) area, will exceed the emissions 

inventory specified in the applicable SIP but the State Governor or designee for SIP 

actions makes a written commitment to EPA to take specific future actions (40 CFR 

93.158(a)(5)(i)(B)).

12.5 Airports Emissions Inventory

Airports in the nonattainment area are planning for future growth. Sacramento County 

has prepared a master plan for this growth that shows an increase in emissions. The 

Sacramento County Airport System is comprised of four airports: Sacramento 

International (SMF), Mather (MHR), Executive (SAC), and Franklin (F32). In addition, 

the County Airport System manages the aviation activities at McClellan Airport on behalf 

of another County agency. Three private airports also operate in Sacramento County:

Rancho Murieta, Rio Linda, and Sunset109. The aircraft emissions inventory forecast 

includes airports from all counties in the Sacramento nonattainment area.

To facilitate future conformity determinations, the projected direct and indirect emissions 

from airport growth are identified for the 2014, and 2017 RFP milestone years, and for 

the 2018 attainment analysis year in Table 12-1. A portion of the airport emissions 

inventory is represented by ground support equipment (GSE) and subject to CARB’s 

2007 In-Use, Off-Road Equipment Regulation. In 2010 CARB approved a suite of 

amendments to the in-use rules that were designed to account for reduced activity 

resulting from the recession and provide regulatory relief to truck and equipment 

owners. The off-road rule revisions delayed implementation requirements for small 

fleets. CARB’s inventory uses the same average GSE emission rates for all counties in 

California and does not reflect fleet size and characteristics specific to each airport. The 

state’s total GSE emissions are dominated by “large fleet” emissions and controls, and 

CARB’s rule requires accelerated and greater control of “large fleets” as compared to 

those of “medium and small fleets.”

This Plan revision combines the GSE emissions with aircraft emissions for each 

planning year and the total is rounded up to the next tenth decimal number. This 

rounding convention is used in estimating emissions inventories included in the Plan.

 

109 Information from Sacramento County Airport System; comment letter dated October 24, 2008.
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Table 12-1 (Revised)

Airport (Aircraft Operations + Ground Support Equipment) Emissions

for the Sacramento Nonattainment Area

Year of Operations

VOC NOX

(tons/day) (tons/day)

2014 Projected Emissions Inventory

Aircraft Operations and GSE 0.7 2.7

2017 Projected Emissions Inventory

Aircraft Operations and GSE 0.7 3.0

2018 Projected Emissions Inventory

Aircraft Operations and GSE 0.7 3.0
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13 REASONABLE FURTHER PROGRESS DEMONSTRATIONS

13.1 Introduction to Reasonable Further Progress

The Clean Air Act specifies reasonable further progress (RFP) requirements for ozone 

nonattainment areas. RFP refers to the general need to obtain a certain level of annual 

incremental reductions in emissions of the relevant air pollutant for the purpose of 

ensuring attainment of the standard by the applicable attainment deadline.

This chapter begins with a discussion of RFP requirements for the 8-hour ozone 

NAAQS. It also describes the methodology for deriving the base year emissions 

inventory, calculating RFP emission targets, assessing creditable reductions, and using 

NOX substitution for VOC reduction shortfalls. Finally, this chapter includes the emission 

reduction summary that demonstrates the RFP targets are met for each of the future 

milestone years. Additional RFP information and documentation are provided in 

Appendix G – Reasonable Further Progress Demonstrations.

13.2 Reasonable Further Progress Requirements

Sections 172(c)(2), 182(b)(1) and 182(c)(2)(B) of the Clean Air Act include RFP 

provisions for reducing emissions in ozone nonattainment areas. The federal 8-hour 

ozone regulations110 (40 CFR 51.910) require that areas classified under subpart 2 as 

“serious and above” need to submit a reasonable further progress plan that shows a 

VOC (and/or NOX) emission reduction of at least 18% over the first 6 years from the 

2002 baseline year (i.e., 2002-2008)111 and 9% between each subsequent milestone 

year (i.e., 2009-2011, 2012-2014, 2014-2017) and 3% in the attainment year. These 

demonstrations are made for future milestone years 2014, 2017, and 2018. A plan to 

demonstrate how progress toward milestone targets in 2008 and 2011 is considered 

moot, since those milestone years are in the past.

13.3 Contingency Measures Requirement

In general, contingency measures are control measures that go into effect if planned 

emission controls fail to reach desired goals and targets. Contingency provisions are 

required under sections 172(c)(9) and 182(c)(9) of the Clean Air Act in the event the 

nonattainment area fails to meet a reasonable further progress milestone or attainment 

deadline. Contingency measures are specific additional controls to be implemented 

automatically without further significant rulemaking activities, such as public hearings or 

legislative review, or without further action by the State or the Administrator (EPA).

 

110 The final 8-hour ozone implementation rule (Phase 2) which includes the reasonable further progress 

requirements was signed and published in the November 29, 2005 Federal Register.

111 The Sacramento Regional Nonattainment Area 8-Hour Ozone Rate-of-Progress Plan (February 2006) 

included over 18% RFP reductions of VOC and NOX emissions for the first 6 years from the 2002 

baseline year.
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Federal guidance112 requires that sufficient contingency measures in the plan be 

adopted to provide a 3% emission reduction beyond what is needed for the reasonable 

further progress requirement. The existing control measure strategy in this plan is 

expected to surpass the amount of emission reductions needed for reasonable further 

progress targets by a margin that meets the contingency measures requirement.

13.4 Methodology for Reasonable Further Progress Demonstrations

The methodology for demonstrating reasonable further progress includes deriving the 

base year and milestone year emissions inventories, calculating RFP emission 

reduction targets, assessing creditable reductions, and using NOX substitution for VOC 

reduction shortfalls.

13.4.1 Base Year and Forecast Milestone Year Emissions Inventories

The first step is compiling the 2002 base year VOC and NOX inventories of 

anthropogenic emissions that are used as the basis for calculating the required percent 

reduction targets. Section 182(b)(1)(B) of the Clean Air Act defines these baseline 

emissions as the total amount of actual VOC or NOX emissions from all anthropogenic 

sources in the nonattainment area, excluding emissions eliminated by federal motor 

vehicle control program (FMVCP) regulations promulgated prior to 1990 and federal 

Reid Vapor Pressure (RVP) fuel regulations promulgated prior to the enactment of the 

Clean Air Act Amendments of 1990.

The VOC and NOX emission inventory forecasts are needed for each future milestone 

year to quantify the emission reductions that are expected to be achieved since the 

2002 base year. The emission forecasts are derived by projecting base year emissions 

using expected growth assumptions and the effects of adopted control measures. In 

addition, the emission inventory includes emission reduction credits (ERCs)

113 to ensure 

they will not interfere with reasonable further progress if they are used in the future.

ERCs may be used as “offsets” to compensate for an increase in emissions from a new 

source or modified major source regulated by the air districts. The “safety margin”114 is 

added to the baseline emission inventory for each milestone year to calculate

reasonable further progress.

13.4.2 RFP Emission Reduction Targets

40 CFR 51.910(a)(1)(ii)(B) requires a 18% reduction between 2002 base year and the 

first milestone year of 2008 and 9% between each subsequent milestone year. For the 

2008 RFP target VOC level, the required 18% RFP emission reduction is applied to the 

adjusted 2002 baseline for 2008 milestone year. For the subsequent milestone RFP 

target VOC level, the required 9% is applied to the previous milestone RFP target VOC 

 

112 ”General Preamble for the Implementation of Title I of the Clean Air Act Amendments of 1990” (57 FR 

13498, April 16, 1992).

113 Chapter 5, Section 5.6.

114 Chapter 11, Table 11-2.
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level minus current milestone‘s FMVCP/RVP adjustments. For the 2018 attainment RFP 

target VOC level, the required 3% is applied to the 2017 milestone RFP target VOC 

level minus 2018 FMVCP/RVP adjustments.

13.4.3 Creditable Control Measure Reductions

When assessing RFP emission reductions creditable toward the percent reductions 

required, there are specific restrictions as listed in section 182(b)(1)(D) of the Clean Air 

Act. For example, post-1990 control benefits are not creditable as reductions if they 

were already required prior to the enactment of the 1990 Clean Air Act Amendments.

These measures include the federal motor vehicle control program, federal RVP fuel 

regulations, corrections to reasonably available control technology (RACT) rules, and 

corrections to motor vehicle inspection and maintenance (I/M) programs.

The creditable VOC reductions from existing control regulations are applied to the 

required RFP target levels. If there are any RFP reduction shortfalls for VOC, the NOX

reductions are included in the RFP demonstration assessment to fulfill the shortfall.

13.4.4 NOX Substitution for VOC Reduction Shortfalls

Any remaining VOC reduction shortfalls are met by using NOX emission reductions.

Section 182(c)(2)(C) of the Clean Air Act allows for the substitution of NOX emission 

reductions in place of VOC reductions to meet the reasonable further progress 

requirements. According to EPA’s NOX Substitution Guidance115, the substitution of NOX

reductions for VOC reductions must be done on a percentage basis, rather than a 

straight ton-for-ton exchange.

Thus, if there is a certain percent VOC reduction shortfall, an equal percentage 

reduction in NOX emissions can be substituted to provide the equivalent reductions 

necessary for meeting the reasonable further progress goals toward attainment. For 

example, the 10.7% apparent shortfall in VOC in 2014 milestone year can be 

substituted with 10.7% NOX reductions.

13.4.5 NOX Substitution Attainment Consistency Requirement

The overall VOC and NOX reduction totals applied to the RFP demonstration must be 

consistent with the SIP attainment control strategy. Therefore, the cumulative amount of 

NOX substitution reductions used toward the RFP requirement cannot be greater than 

the total NOX reductions dictated by the modeled attainment demonstration. This 

attainment consistency requirement is meant to prevent the substitution of NOX

reductions that would not lead to progress toward attaining the ozone standard.

The current air quality modeling analysis from the Central California Ozone Study 

(CCOS) shows that attainment can be reached with different combinations of VOC and 

NOX control. Photochemical modeling results indicate that both VOC and NOX

 

115 Environmental Protection Agency (OAQPS), “NOX Substitution Guidance”, December 1993.
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reductions provide ozone benefits in the Sacramento region, but on a ton for ton basis 

NOX reductions provide greater ozone benefits than VOC reductions. Therefore, a 

substantial use of NOX substitution would be consistent with current analyses of ozone 

attainment strategies in the Sacramento nonattainment area.

13.5 Calculations of Reasonable Further Progress Demonstrations

Table 13-1 contains a summary of the calculations for determining whether reasonable 

further progress is achieved for the required milestone targets for 2014, 2017, and the 

2018 attainment demonstration year. Projected future VOC and NOX emission 

reductions will provide the required RFP reductions, as well as a 3% contingency 

margin.

The reasonable further progress demonstrations are achieved by forecasted emission 

reductions from existing control regulations and already adopted control measures. No 

emission reductions from new measures identified in Chapter 7 are used in the 

reasonable further progress demonstrations or in the RFP contingency demonstration.

Also, both VOC and NOX emission reductions are needed to meet the RFP reduction 

targets as shown in Figure 13-1. The NOX substitution is used on a percentage basis to 

cover any VOC percentage shortfalls. Since the total sum of NOX emission reductions 

(14%) used to cover any VOC shortfalls is less than the total NOX reductions (54%) 

required for attainment116, the use of NOX substitution for RFP purposes is consistent 

with the attainment demonstration strategy.

 

116 2018 attainment demonstration analysis in Table 8-1 indicates NOX reduction needed from 2002 base 

year = 1-(91/196) = 54%
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Table 13-1

Calculation of Reasonable Further Progress Demonstrations

Sacramento Nonattainment Area

A CARB RFP and Pre-90 RFP write-up March 26, 2013, email transmittal to SMAQMD.

B Sum of emissions from Chapter 5, Tables 5-2 and 5-3 and motor vehicle “safety margin” from Chapter 

11, Table 11-1. The emission reduction credits (are included in emission inventory) see Tables 5-4 and 5-

5.

C CARB provided the non-creditable FMVCP/RVP adjustments, using CA MVCP method in Appendix G.

VOC Emission Calculations – Tons/Day 2002 2014 2017 2018

Baseline VOC B 146.7 106.0 99.9 98.7

Non-Creditable FMVCP/RVP Adjustment C 0.0 10.9 11.9 12.2

RACT Corrections 0 0 0 0

Adjusted 2002 Baseline VOC in milestone year 146.7 135.8 134.8 134.5

RFP commitment for VOC reductions from new measures 0 0 0 0

Future Year VOC with existing and proposed measures 106.0 99.9 98.7

Required % change since previous milestone year (VOC or 

NOX) compared to 2002 9% 9% 3%

Target VOC levels 91.5 82.3 79.5

Apparent shortfall in VOC 14.5 17.6 19.2

Apparent shortfall in VOC, % 10.7% 13.0% 14.3%

VOC shortfall previously provided by NOX substitution, % 0.0% 10.7% 13.0%

Actual VOC shortfall, % 10.7% 2.3% 1.2%

NOX Emission Calculations – Tons/Day 2002 2014 2017 2018

Baseline NOX

B 164.8 92.6 80.0 76.9

Non-Creditable FMVCP Adjustment C 0.0 10.4 11.0 11.2

Adjusted 2002 Baseline NOX in milestone year 164.8 154.4 153.8 153.6

RFP commitment for NOX reductions from new measures 0 0 0 0

Change in NOX since 2002 61.8 73.8 76.7

Change in NOX since 2002, % 40.0% 48.0% 49.9%

NOX reductions since 2002 already used for RFP substitution 

and contingency through last milestone year, % 0.0% 13.7% 16.0%

NOX reductions since 2002 available for RFP substitution and 

contingency in this milestone year, % 40.0% 34.3% 33.9%

Change in NOX since 2002 used for VOC substitution in this 

milestone year, % 10.7% 2.3% 1.2%

Change in NOX since 2002 available for contingency in this 

milestone year, % 3.0% 3.0% 3.0%

Change in NOX since 2002 surplus after meeting substitution 

and contingency needs in this milestone year, % 26.3% 31.9% 32.6%

RFP Met? YES YES YES

Contingency Met? YES YES YES
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Figure 13-1

Summary of Reasonable Further Progress Demonstrations

Sacramento Nonattainment Area

Reasonable further progress (RFP) demonstrations are achieved by forecasted emission reductions 

from existing control strategies and accounting for emissions growth. Both VOC and NOX emission 

reductions are needed to meet the RFP reduction targets.

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

 2014 RFP 2017 RFP 2018 RFP Reduction From Adjusted 2002 Baseline in Milestone Year

NOx Reduction Surplus

3% Contingency

NOx Substitution

VOC Reductions

RFP Reduction Target
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14 SUMMARY AND CONCLUSIONS

14.1 8-Hour Ozone Nonattainment Designation for Sacramento Region

The 1997 federal 8-hour ozone standard lowered the health-based limit for ambient 

ozone concentration from 0.12 parts per million of ozone averaged over one hour to 

0.08 parts per million of ozone averaged over eight hours. An area’s nonattainment 

designation is based on whether the ozone design value concentration117 for any of the 

monitoring sites in the area exceeds the national ambient air quality standard (NAAQS).

The Sacramento region is designated a nonattainment area, and includes all of 

Sacramento and Yolo counties and portions of Placer, El Dorado, Solano, and Sutter 

counties.

14.2 “Severe” 8-Hour Ozone Classification with 2019 Attainment Deadline

Nonattainment areas are classified as marginal, moderate, serious, severe, or extreme 

areas depending on the magnitude of the highest 8-hour ozone design value for the 

monitoring sites in the nonattainment area. In 2004, the Sacramento region was

classified as a “serious” nonattainment area with an attainment deadline of June 15, 

2013. This classification was based on the 8-hour ozone design value of 107 ppb at 

Cool, calculated from ozone concentrations monitored from 2001 to 2003.

However, since the Sacramento region needs to rely on the longer term emission 

reduction strategies from state and federal mobile emission standard programs, the 

Sacramento region cannot meet the 2013 attainment date for serious nonattainment 

areas. Consequently, on February 14, 2008, CARB on behalf of the air districts in the 

Sacramento region submitted a letter to EPA requesting a voluntary reclassification 

(bump-up) of the Sacramento Federal Nonattainment Area from a “serious” to a 

“severe” 8-hour ozone nonattainment area with an extended attainment deadline of 

June 15, 2019. EPA approved the reclassification request on May 5, 2010 (75 FR 

24409).

14.3 Trend in Ozone Air Quality Shows Improvement

The progress toward attainment is measured by analyzing ambient air quality data 

collected at various monitoring sites over a period of many years (1990-2007). There 

are currently 16 ozone monitoring stations located throughout the Sacramento region 

that are operated by either local air districts or the California Air Resources Board.

The annual number of 8-hour ozone exceedance days recorded at the peak monitoring 

sites fluctuates from year to year due to meteorological variability and changes in 

precursor emission patterns. The most frequent exceedances of the federal 8-hour 

ozone standard occur at the region’s eastern monitoring sites (Cool, Folsom, Placerville, 

 

117 The 8-hour ozone design value is the standard-related indicator calculated as the annual 4th

-highest 

daily maximum 8-hour ozone concentration averaged over 3 years.
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and Auburn). The 18-year trend line indicates a decline in the overall average peak 

number of annual exceedance days, from about 33 down to 22.

The peak 8-hour ozone design value concentration also varies from year to year and 

occurs at the eastern monitoring sites in the Sacramento region. The overall 18-year 

trend line shows a decline, from 108 ppb down to about 100 ppb. The design value has 

improved from being 24 ppb (or 28%) over the standard118 down to about 16 ppb (or 

19%).

14.4 VOC and NOX Emissions Inventory Forecasted to Decline

Ozone is not directly emitted into the atmosphere, but is a pollutant produced by 

photochemical reactions in the air involving volatile organic compounds (VOC) and 

nitrogen oxides (NOX). Therefore, planning efforts to evaluate and reduce ozone air 

pollution include identifying and quantifying the various processes and sources of VOC 

emissions (such as solvents, surface coatings, and motor vehicles) and NOX emissions 

(such as motor vehicles and other fuel combustion equipment).

EPA emission inventory guidance requires the planning emissions inventory to be 

based on estimates of actual emissions for an average summer weekday, typical of the 

ozone season (May – October). The anthropogenic emissions inventory is first divided 

into four broad source categories: stationary sources, area-wide sources, on-road motor 

vehicles, and other mobile sources. Each of these major categories is further defined 

into more descriptive equipment types and specific emission processes. The biogenic 

VOC emissions from vegetation for natural areas, crops, and urban landscapes are 

estimated separately from the anthropogenic inventory.

The 2002 base year anthropogenic planning inventory is estimated to be 147 tons per 

day of VOC emissions and 165 tons per day of NOX emissions for the Sacramento 

nonattainment area. The base year emissions are used to forecast future year 

inventories by using socio-economic growth indicators and the post-2002 emission 

reduction effects of existing control strategies. Also, potentially available pre-2002 

emission reduction credits (ERCs) are included as additional growth in future years to 

ensure that their use will not be inconsistent with the reasonable further progress and 

attainment targets.

The 2002 base year emissions and emission forecasts out to 2018 for the Sacramento 

nonattainment area are summarized by the four major emission categories in Figure 14-

1. The VOC and NOX emission forecasts show significant declines in mobile source 

emissions, despite increasing population, vehicle activity, and economic development in 

the Sacramento region.

 

118 Federal 8-hour ozone standard = 84 ppb.
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Figure 14-1

VOC and NOX Emission Forecasts*

Sacramento Nonattainment Area

*Post-2002 stationary source emission forecasts include ERCs (4 tpd VOC and 3 tpd NOX).

14.5 Air Quality Modeling Analysis Indicates Additional Emission Reductions Are 

Needed for Attainment

Updated photochemical air quality grid modeling was developed to simulate base case 

episodes of high ozone formation as part of the extensive air monitoring and data 

analysis conducted for the 2000 Central California Ozone Study. The air quality model 

was then run with 2002 baseline year emissions and future year emissions forecasts 

(including VOC and NOX ERCs) to see if the ozone standard would be attained with

existing control strategies. The relative decline in future ozone concentrations shown in 

the photochemical modeling results predicted attainment at all ozone monitors in 2018

except for two sites (Cool and Folsom) located in the eastern part of the Sacramento 

region.

Additional air quality modeling runs of across-the-board control scenarios were 

conducted. The air quality modeling analysis shows that attainment can be reached by 

2018 with different combinations of VOC and NOX control. The modeling results indicate 

that both VOC and NOX reductions provide ozone benefits in the Sacramento region, 

but on a ton for ton basis NOX reductions provide greater ozone benefits than VOC 

reductions. More specific conclusions regarding attainment targets for the Sacramento 

region’s peak ozone monitoring site at Cool are provided in the attainment 

demonstration evaluation.

0

20

40

60

80

100

120

140

160

180

200

2002 2014 2017 2018 2002 2014 2017 2018

Emissions (tons/day)

Stationary

Area-Wide

On-Road Motor

Vehicles

Other Mobile Sources

VOC NOx
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Summary and Conclusions

Page 14-4

14.6 Proposed Regional and Local Control Measures

The Sacramento SIP control strategy relies on the following components:

1. Reductions from existing control measures and adopted rules,

2. Reductions from new state and federal regulations, and

3. Reductions from defined new SIP local and regional measures.

The proposed SIP emissions control strategy includes reductions of both VOC and NOX

air pollutants. A single NOX pollutant strategy is not appropriate because, even though 

VOC measures are not as effective as NOX, they still provide needed reductions. 

Moreover, many existing statewide and local control programs will inherently achieve 

reductions from both ozone precursors.

EPA’s final 8-hour ozone implementation rule (pursuant to section 172(c)(1) of the 

Clean Air Act) requires the attainment SIP submittal to include adopting all reasonably 

available control measures (RACM) necessary to demonstrate attainment as 

expeditiously as practicable and to meet any RFP requirements. EPA’s RACM policy 

indicates that areas should consider all candidate measures that are potentially 

reasonably available. Sources of potentially reasonable measures include measures 

adopted in other nonattainment areas, measures that the EPA has identified in 

guidelines or other documents, and any measures that have been suggested for the 

particular nonattainment area during a public comment period.

Areas should consider all reasonably available measures for implementation in light of 

local circumstances. However, areas need only adopt measures if they are both 

economically and technologically feasible and cumulatively will either advance the 

attainment date (by one year or more) or are necessary for RFP. This plan contains 

required reasonably available control measures.

The total emission reductions from the new measures are an enforceable commitment 

in the SIP. The proposed regional and local control measures include estimates of the 

emission reductions from each of the individual measures, but the commitment is for 

emissions reductions from the aggregate of all proposed new measures combined.

Because new measures provide a buffer to attain standards by 2018, and are not 

included in the Reasonable Further Progress demonstration, if a particular measure 

does not get its expected emission reductions, it does not compromise the attainment 

demonstration or Reasonable Further Progress demonstration. An explicit commitment 

is made to the reductions associated with the on-road mobile source incentive program

for purposes of transportation conformity.

The following Table 14-1 contains a summary of the proposed new regional and local

control measures and expected VOC and NOX emission reductions. Emission benefits 

from these new committal measures are estimated to provide reductions of 2.7 tons per 

day of VOC and 1.1 tons per day of NOX in 2018.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Summary and Conclusions

Page 14-5

Table 14-1 Summary of New Regional and Local Proposed Control Measures Sacramento 

Nonattainment Area

Control Measure Name 2018 Emission Reductions 

(tpd)

VOC NOX

Regional Non-regulatory Measures

Regional Mobile Incentive Program – On-road <0.1 0.5

Regional Mobile Incentive Program – Off-road <0.1 <0.1

Spare The Air Program <0.1 <0.1

SACOG Transportation Control Measures - -

Urban Forest Development Program 0 - 0.2 -

Total Regional Non-regulatory Measures 0.1 0.5

Local Regulatory Measures*

Architectural Coating 1.5 -

Automotive Refinishing 0.2 -

Degreasing/Solvent Cleaning 0.7 -

Graphic Arts na -

Miscellaneous Metal Parts and Products <0.1 -

Natural Gas Production and Processing 0.1 -

Boilers, Steam Generator, and Process Heaters - 0.2

IC Engines - <0.1

Large Water Heaters and Small Boilers - 0.2

Total Local Regulatory Measures* 2.6 0.5

Total Reductions* 2.7 1.1

Note: Numbers are truncated to one decimal place. na = not available

*Total reductions are summed from untruncated values. See summary table in Appendix C – Proposed Control Measures.

The following Table 14-2 contains a summary of SACOG transportation control 

measures (TCMs) that are included in the Sacramento region’s federal 8-hour ozone 

plan. The TCMs include new and continuing projects and funding programs.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Summary and Conclusions

Page 14-6

Table 14-2 Summary of SACOG Transportation Control Measures New and Continuing 

Projects and Funding Programs

TCM Name and (ID) Implementing 

Agency

Implement or 

Completion 

Date

VOC

Reduction

(Tons/Day)

NOX

Reduction

(Tons/Day)

Intelligent Transportation Systems 

(ITS) Projects

Arden Way Smart Corridor (ITS-1) City of Sac - Dept of 

Transportation 2008 --- ---

Sacramento Traffic Operations 

Center (ITS-2)

City of Sac - Dept of 

Transportation 2009 --- ---

STARNET Implementation (ITS-4) SACOG 2009 --- ---

Park and Ride Lots / Transit Centers

El Dorado Central Park and Ride 

Facility (TF-1)

El Dorado County 

Transit 2009 --- ---

Improvements to Loomis Multimodal 

Center (TF-2)

Town of Loomis –

Dept of Public Works 2010 --- ---

13th and 16th St :Light Rail Station 

Improvements (TF-3)

Sac Regional Transit 

District 2009 --- ---

Transit Service Funding Programs

Transit Vehicle Acquisitions (TR-1) Various Agencies Various 

Dates --- ---

Transit Operations (TR-2) Various Agencies Various 

Dates --- ---

Other Specific Funding Programs

Freeway Service Patrol (AQ-1) Sac Transportation 

Authority Through 2018 --- ---

SECAT Program (AQ-2) SMAQMD Through 2018 ---

a

---

a

Spare The Air Program (AQ-3) SMAQMD Through 2018 ---

b

---

b

MTP Regional Funding Programs

Air Quality Funding Program (FP-1) Various Agencies Through 2018 --- ---

Bicycle and Pedestrian Funding 

Program (FP-2) Various Agencies Through 2018 --- ---

Transportation Demand 

Management Funding Program (FP3)Various Agencies Through 2018 --- ---

Community Design Funding 

Program (FP-4) Various Agencies Through 2018 --- ---

Miscellaneous Projects

Light Rail Grade Separation at Watt 

Ave and Folsom Blvd (M-2)

Sac County – Dept of 

Transportation 2009 --- ---

Dry Creek Parkway Trail Phase 1 Sac County – Dept of 

Transportation 2011

Total Emission Reductions --- ---

a

SECAT emission reductions are assumed to be included in SMAQMD mobile source control measure ONMS-HD-1.

b

Spare The Air emission reductions are assumed to be included in SMAQMD control measure TCM-ONMS-ED-1.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Summary and Conclusions

Page 14-7

14.7 2018 Attainment Demonstration

Attainment of the 1997 8-hour ozone NAAQS is evaluated for a 2018 “severe” 

classification scenario, based on modeling results for the peak ozone site (Cool) in the 

region. The modeled VOC and NOX emission forecasts for 2018 incorporate growth 

assumptions and the estimated reductions associated with the existing control strategy.

The photochemical modeling results were used to estimate the percent reductions 

needed from the 2018 emission forecasts in order to achieve the 1997 federal 8-hour 

ozone standard (84 ppb).

The projected 2018 emission inventory with adopted control measures, including 

emission reduction credits and a safety margin in the motor vehicle emissions budgets

demonstrates attainment by the 2018 “severe” classification deadline. New local control 

measures provide a buffer in the attainment demonstration. The attainment 

demonstration assessment for the Sacramento nonattainment area is summarized in 

Table 14-3.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Summary and Conclusions

Page 14-8

Table 14-3 Summary of Attainment Demonstration for 8-Hour Ozone NAAQS 2018 

“Severe” Classification Scenario

Sacramento Nonattainment Area VOC (tpd) NOX (tpd)

Summary of 2009 Plan Attainment Demonstration

A) 2002 Planning Emissions Inventory 1160.3 196.1

B) 2018 Planning Emissions Inventory with Existing Controls 1121.1 104.1

C) Attainment Emission Reduction in percentage 23.3% 12.5%

D) SIP Emissions Target: Line B × (1 – Line C) 117.1 91.1

E Percentage Emission Reduction Required for Attainment: 

( 1 – (Line D ÷ Line A) ) × 100% 27.0% 53.6%

Revised Emissions Targets

F) Updated 2002 Inventory 3146.7 164.8

G) Updated SIP Emissions Target: Line F × ( 1 – Line E ) 107.1 76.5

Revised Attainment Demonstration

H) Updated 2018 Inventory 397.7 73.9

I Motor Vehicle Emissions Budgets Safety Margin 41 3

J) Emission Reductions in 2018 from Remaining Regional/Local Control 

Measures 5,7 2.7 1.1

K Emissions Reductions in 2018 from Remaining State/Federal Control 

Measures 6,7 5.7 0.3

L) Total Emissions in 2018 with All Remaining Controls:

( Line H + Line I - Line J – Line K )

90.3 75.5

M) Is Attainment Demonstrated? (Is Line L ≤ Line G?) Yes

1. The 2009 inventory is shown in Appendix A8.

2. The percent emission reduction targets for attainment are based on modeling results. Figure 8-1 

Point A.

3. Chapter 5. Tables 5-2 and 5-3 include ERCs (ERC details are in Tables 5-4 and 5-5).

4. Chapter 11 Table 11-1

5. Appendix C, Table of Emission Reductions by Air District, Page C-5.

6. Chapter 7. Table 7-2, sum of expected emission reductions from New Emission Standards for 

Recreational Boats and Expanded Off-Road Rec. Vehicle Emission Standards.

7. These reductions provide a buffer for meeting attainment targets.

14.8 Pollutant Transport from Upwind Bay Area Region

The air quality in the Sacramento region is impacted by pollutant transport from the San 

Francisco Bay Area. Delta breezes carry air pollutants from upwind Bay Area emission 

sources into the Sacramento region, and these pollutants may contribute to ozone 

formation during the same day or the following days. The California Air Resources 

Board has determined that the relative impact from this Bay Area transport can be 

considered overwhelming, significant, or inconsequential on various days119, depending 

on meteorological conditions. CARB has also made findings that pollutant transport 

 

119 California Air Resources Board, “Ozone Transport: 2001 Review”, April 2001.
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Summary and Conclusions

Page 14-9

from the San Joaquin Valley can have significant or inconsequential impact120 on air 

quality in the Sacramento region.

States are responsible for submitting SIPs for all areas of their State and need to 

demonstrate attainment in all areas addressing intrastate transport where appropriate.

The photochemical grid modeling study includes the northern and central regions of 

California in the modeling domain, and was used to address and account for air

pollutant transport impacts among the San Francisco Bay Area, San Joaquin Valley, 

Sacramento Valley, and Mountain Counties air basins.

CARB modeling for the attainment demonstration for the Sacramento nonattainment 

area used domain-wide emission reductions to characterize future ozone reductions at 

peak ozone monitoring stations. Therefore, for our area to attain, reductions in 

forecasted emissions necessary and committed to in Sacramento must also be 

achieved in the areas that significantly impact the region. In other words, the attainment 

demonstration for the Sacramento nonattainment area is predicated on the San 

Francisco Bay Area and the San Joaquin Valley also achieving an equivalent additional 

percent reduction of VOC and NOX emissions in their forecasted 2018 inventory. The 

reductions could come from either state or upwind regions’ local measures, but we 

understand that CARB has committed to address the reduction requirement by 

implementing the new state measures statewide, which are expected to achieve similar

reductions in the Bay Area and San Joaquin Valley.

In addition, pollutant transport from the Sacramento region can potentially impact the air 

quality in other regions under certain meteorological conditions. For example, CARB 

analyses have determined that ozone violations at the Grass Valley monitoring station 

in Nevada County are considered to be overwhelmingly due to transport from the 

Sacramento region.121 Emission reduction strategies in the Sacramento region will 

benefit their efforts to attain the federal ozone standards.

14.9 Weight-of-Evidence Determination

Attainment demonstrations based on photochemical modeling can be strengthened by 

supplemental evidence from additional modeling analyses and from considering 

modeling outputs other than the attainment test results. More diverse non-modeling and 

observational methods analyzing air quality, meteorological, and emissions data can 

also be used to corroborate the modeling predictions. EPA guidance122 specifies that a 

comprehensive weight-of-evidence approach should be undertaken to support the 

modeled attainment demonstration.

Since 1999, the number of area-wide exceedance days has decreased by over 10%.

The ozone design value has decreased by 5%. A smaller portion of the nonattainment 

 

120 Ibid.

121 Ibid.

122 “Guidance on the Use of Models and Other Analyses in Attainment Demonstrations for the 8-hour 

Ozone NAAQS” (EPA, October 2005, p. 28-33).
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Summary and Conclusions

Page 14-10

region violates the 1997 federal ozone standard, and the western most and eastern 

most portions of the region attain. Analyses show that these improvements are due to 

emissions reductions, not favorable weather conditions.

The overall conclusions of the weight-of-evidence analyses support the attainment 

demonstration when taking into account: 1) the ozone modeling results and that NOX

reduction will be critical to attainment, and 2) the general decline in emissions, ambient 

air pollutants, and ozone trend indicators. These evaluations are consistent with the 

overall NOX and VOC emission control strategy in reducing peak ozone in the region.

14.10 Transportation Conformity and Motor Vehicle Emissions Budgets

Under the federal Clean Air Act, federal agencies may not approve or fund 

transportation plans and projects unless they are consistent with state air quality 

implementation plans (SIPs). Conformity with the SIP requires that transportation 

activities not cause new air quality violations, worsen existing violations, or delay timely 

attainment of the national ambient air quality standards (NAAQS). Conformity 

regulations state that emissions from transportation plans and projects must be less 

than or equal to the motor vehicle emissions budgets established by reasonable further 

progress, attainment or maintenance plans (SIPs). (40 CFR 93.118)

Table 14-4 lists the proposed new transportation conformity budgets for the 2014, and 

2017 RFP milestone years, and the 2018 attainment analysis year for the Sacramento 

nonattainment area. The proposed budgets incorporate the recent on-road motor 

vehicle emission inventory factors of EMFAC2011, updated travel activity data, latest 

control strategies, and a safety margin.

Table 14-4

Proposed New Motor Vehicle Emission Budgets*

Sacramento Nonattainment Area

NOX VOC

2014 2017 2018 2014 2017 2018

ARB Inventories for Conformity (Tons per 

Day) 46 37 34 21 17 16

Safety Margin 3 2 3 2 1 1

Budgets 49 39 37 23 18 17

*All motor vehicle emission budget years include regional incentive benefits. State control measure reductions are 

only included in 2018.

This ozone plan includes the updated on-road motor vehicle emissions and the 

proposed transportation budgets that assume vehicle activity levels based on the road 

and transit projects contained in SACOG’s Metropolitan Transportation Improvement 

Plan (2013/16 MTIP) and MTC’s Plan Bay Area Preferred Land Use 

Scenario/Transportation Investment Strategy (May 11, 2012). The transportation 

analysis for the 2013/16 MTIP relied on SACOG’s new SACSIM regional travel 
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Summary and Conclusions

Page 14-11

forecasting model to estimate future traffic volumes in the 6-county Sacramento region.

This model also incorporated the latest SACOG land use assumptions from the 

Metropolitan Transportation Plan/Sustainable Communities Strategies (2012 

MTP/SCS).

If these proposed new motor vehicle emission budgets are determined to be adequate 

for transportation conformity purposes by EPA, they will replace the prior 2014 and 

2017 budgets found adequate in 2009. The Metropolitan Planning Organizations, 

SACOG and MTC, must ensure that the aggregate transportation emissions in the 

region stay below these levels when approving new metropolitan transportation plans 

and transportation improvement programs, even if the mix of projects changes or 

growth increases. These new, adequate 8-hour MVEBs will remain in effect until other 

budgets are found adequate or approved by EPA.

Vehicle Miles Traveled Offset (VMT Offset)

Section 182(d)(1)(A) of the federal Clean Air Act applies to areas classified as severe or 

extreme nonattainment of the National Ambient Air Quality Standard (NAAQS) for 

ozone. The Sacramento Federal Ozone Nonattainment Area is currently designated as 

Severe-15, (75FR24409) and is subject to the requirement to offset any growth in 

emissions resulting from an increase in vehicle miles travelled. A detailed VMT offset 

demonstration was prepared by California Air Resources Board and is included in 

Appendix F – Motor Vehicle Emission Budgets and VMT Offset Demonstration as part 

of the 2013 revision to the Sacramento Regional 8-Hour Ozone Attainment and 

Reasonable Further Progress Plan. The analysis shows there are sufficient 

transportation control strategies and TCMs to offset the emissions increase due to 

growth in VMT and demonstrates compliance with the requirements of Section 

182(d)(1)(A) of the federal Clean Air Act.

14.11 Updated Emissions Inventory for General Conformity

General conformity is the federal regulatory process for preventing major federal actions 

or projects from interfering with air quality planning goals. Conformity provisions ensure 

that federal funding and approval are given only to those activities and projects that are 

consistent with state air quality implementation plans (SIPs). Conformity with the SIP 

means that major federal actions will not cause new air quality violations, worsen 

existing violations, or delay timely attainment of the national ambient air quality 

standards (NAAQS). Examples of general federal actions that may require a conformity 

determination include, but are not limited to, the following: leasing of federal land; 

private construction on federal land; reuse of military bases; airport construction and 

expansions, and construction of federal office buildings.

A federal agency may demonstrate conformity by showing that the total of direct and 

indirect emissions from the action is accounted for in the applicable SIP’s attainment or 

maintenance demonstration. Therefore, the updated emissions inventory in this 8-hour 

ozone attainment demonstration plan would be applicable for general conformity 
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Summary and Conclusions

Page 14-12

purposes. Specific emission budgets for airport operations are identified for future 

years.

14.12 Reasonable Further Progress Demonstration Achieved

The federal 8-hour ozone regulations123 require that areas classified as “serious or 

above” submit a reasonable further progress (RFP) demonstration plan that provides for 

at least 3% average annual reductions of VOC (and/or NOX) emissions every 3-year 

period after 2008 out to the attainment year. The RFP demonstration must fully account 

for emissions growth when calculating the net emission reductions.

The RFP evaluation is based on the emission inventory forecasts, which assume 

expected growth rates and current control measures. The 3-year RFP demonstrations

are achieved through VOC and NOX emission reductions for the milestone years 2014, 

2017, and the 2018 attainment analysis year. Figure 14-2 shows the percentages of 

VOC and NOX emission reductions used to meet the RFP reduction goals. A NOX

reduction surplus is used to meet a 3% contingency margin requirement.

Figure 14-2

Summary of Reasonable Further Progress Demonstrations

Sacramento Nonattainment Area

14.13 Future Ozone Planning Efforts

The proposed Sacramento Regional 8-Hour Ozone Attainment and Reasonable Further 

Progress Plan reflects the best available information at this time. However, emission 

inventories, modeling analyses, and control strategies will continue to be updated and 

 

123 Federal Register, November 29, 2005, p. 71634.

0%

10%

20%

30%

40%

50%

60%

70%

80%

90%

 2014 RFP 2017 RFP 2018 RFP Reduction From Adjusted 2002 Baseline in Milestone Year

NOx Reduction Surplus

3% Contingency

NOx Substitution

VOC Reductions

RFP Reduction Target
2013 Revisions to the Sacramento Regional 8-Hour Ozone Attainment

and Reasonable Further Progress Plan September 26, 2013

Summary and Conclusions

Page 14-13

re-evaluated. Revisions to this plan can be made at any time if new information 

indicates a change is needed. Each air district has prepared and submitted RACT SIPs

for major sources (emissions equal to or greater than 25 tons per year) under severe 

area requirements.

Milestone Reports

Section 182(g) of the Clean Air Act Amendments requires that progress (milestone) 

reports be prepared to evaluate whether actual emission reductions meet the minimum 

reasonable further progress targets. In addition, the milestone analysis assesses the 

control measures that have actually been adopted and implemented in comparison to 

the overall comprehensive attainment strategy contained in the ozone plan. The 2011 8-

hour ozone milestone report was the Sacramento Regional 8‐Hour Ozone Milestone 

Report: 2011 Milestone Year (SMAQMD, 2012)124. The air districts will prepare

subsequent reports every three years out to the attainment year.

 

124 SMAQMD et al. Sacramento Regional 8‐Hour Ozone Milestone Report: 2011 Milestone Year. 

Sacramento Metropolitan Air Quality Management District et al: Sacramento, CA. [2012.]