State of California

Staff Report

Minor Updates to Yuba City-Marysville 

PM2.5 Maintenance Plan and Redesignation 

Request

Release Date: January 17, 2014

Scheduled for Consideration: February 20, 2014

 

California Environmental Protection Agency

AIR RESOURCES BOARD
This document has been reviewed by the staff of the California Air Resources Board 

and approved for publication. Approval does not signify that the contents necessarily 

reflect the views and policies of the Air Resources Board, nor does the mention of trade 

names or commercial products constitute endorsement or recommendation for use.
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TABLE OF CONTENTS

I. BACKGROUND.............................................................................................................. 1

II. REVISED EMISSION INVENTORY................................................................................ 1

III. ADDITIONAL ANALYSES SUPPORTING ATTAINMENT RESULTS FROM 

PERMANENT AND ENFORCEABLE EMISSION REDUCTIONS................................... 3

IV. DISCUSSION OF FUTURE YEAR COMPOSITION USED IN CALCULATION OF THE 

2024 DESIGN VALUE.................................................................................................... 8

IV. CONTINGENCY PLAN................................................................................................... 9

V. STAFF RECOMMENDATION ........................................................................................ 9
1

I. BACKGROUND

In December 2006, the U.S. Environmental Protection Agency (U.S. EPA) lowered the 

24-hour national ambient air quality standard (standard) for PM2.5 from 65 g/m3to 

35 g/m3. Effective December 14, 2009, U.S. EPA designated the Yuba City-Marysville 

Area as nonattainment for this more stringent 24-hour PM2.5 standard. The federal 

Clean Air Act (CAA) establishes planning requirements for those areas that exceed the 

health-based standards. These nonattainment areas must develop and implement a 

State Implementation Plan (SIP) that demonstrates how they will attain the standards by 

specified dates. 

Since the Yuba City-Marysville nonattainment area attained the 24-hour PM2.5 

standard prior to the SIP submittal deadline, the area was eligible for reduced regulatory 

requirements under the U.S. EPA’s Clean Data Policy for the Fine Particulate National 

Ambient Air Quality Standards. The Feather River Air Quality Management District 

(District) addressed the remaining SIP requirements in the Yuba City-Marysville PM2.5 

Nonattainment Area Redesignation Request and Maintenance Plan (Redesignation 

Request/Maintenance Plan). The Redesignation Request/Maintenance Plan was 

approved by the District Board and by the Air Resource Board (ARB) on April 1, 2013 

and April 25, 2013, respectively. On May 23, 2013, ARB submitted the plan to 

U.S. EPA. 

In 2013, U.S. EPA was directed by the Courts to implement the PM2.5 standard under 

subpart 4 of the Clean Air Act (Act) rather than subpart 1. In order to evaluate and 

approve the Redesignation Request/Maintenance Plan under subpart 4 of the Act, 

U.S. EPA staff requested additional technical information on several elements of the 

Plan. The Minor Updates to Yuba City-Marysville PM2.5 Maintenance Plan and 

Redesignation Request (Minor Updates) provides U.S. EPA with the additional

information to approve the Redesignation Request/Maintenance Plan and redesignate 

the Yuba City-Marysville PM2.5 nonattainment area to attainment for the PM2.5 

standard.

II. REVISED EMISSION INVENTORY

In order to address subpart 4 requirements, emission inventories that were originally 

submitted as part of the Redesignation Request/Maintenance Plan are expanded to 

include ammonia (NH3) and Volatile Organic Carbon (VOC). To support the 

maintenance demonstration and document the emission reductions that provided for 

attainment, the 2011 attainment year emission inventory was augmented with an earlier 

year inventory, 2005, when the region was still over the 24-hour PM2.5 standard. Table 

1 lists NOx, PM2.5, SOx, NH3, and VOCs emissions for 2005, 2011, 2017, and 2024.
2

Table 1. Yuba City-Marysville PM2.5 Nonattainment Area Emission Inventories*

Category 2005 2011 2017 2024

NOx

Stationary Sources 4.4941 4.3908 4.7717 4.3239

Areawide Sources 1.1075 1.0876 1.2791 1.2748

Mobile Total 20.9369 13.8089 9.7553 6.3056

On-Road Mobile 12.8955 8.3763 5.3** 3.1**

Other Mobile 8.0414 5.4326 4.6179 3.3593

Grand Total 26.5385 19.2873 15.9687 12.0580

PM2.5

Stationary Sources 0.9812 0.8732 1.0446 1.1248

Areawide Sources 4.0302 3.8288 4.0732 3.9642

Mobile Total 0.7698 0.5568 0.389 0.3171

On-Road Mobile 0.3557 0.2688 0.2** 0.2**

Other Mobile 0.4141 0.288 0.2182 0.1438

Grand Total 5.7812 5.2588 5.5360 5.4328

SOx

Stationary Sources 0.1295 0.1254 0.2375 0.2387

Areawide Sources 0.1555 0.1478 0.2518 0.2471

Mobile Total 0.2887 0.0806 0.0845 0.0848

On-Road Mobile 0.0887 0.0246 0.028 0.28

Other Mobile 0.2 0.056 0.0563 0.0567

Grand Total 0.5737 0.3538 0.5738 0.5706

NH3

Stationary Sources 0.306 0.3575 0.4131 0.483

Areawide Sources 4.5568 4.4945 4.3461 4.2563

Mobile Total 0.2245 0.1946 0.1702 0.1629

On-Road Mobile 0.2225 0.1926 0.1682 0.1609

Other Mobile 0.002 0.002 0.002 0.002

Grand Total 5.0873 5.0466 4.9294 4.9022

VOCs

Stationary Sources 3.8225 4.0252 4.5383 4.107

Areawide Sources 5.754 5.4627 6.2757 6.4784

Mobile Total 6.6997 5.1509 3.4347 2.8421

On-Road Mobile 3.7252 2.8017 1.4752 1.1129

Other Mobile 2.9745 2.3492 1.9595 1.7292

Grand Total 16.2762 14.6388 14.2487 13.4275

* Displayed to ten thousandths place to show change in emission. 

** Future year on-road mobile inventory for NOx and PM2.5 replaced with motor vehicle emission budgets.
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III. ADDITIONAL ANALYSES SUPPORTING ATTAINMENT RESULTS FROM 

PERMANENT AND ENFORCEABLE EMISSION REDUCTIONS

The CAA requires demonstration that the air quality improvement that resulted in 

attainment of the standard can be reasonably attributed to permanent and enforceable 

emission reductions. The Yuba City-Marysville Area first attained the standard in 2008 

and continues to attain through 2012. The 24-hour design value decreased from 

36 g/m3in 2005 to 26 g/m3in 2012. This is a 10 g/m3decrease, which represents a 

28 percent reduction. The 2012 design value is 26 percent below the standard. 

The analyses presented in this section provides additional information requested by 

U.S. EPA that the improvement in PM2.5 air quality can be reasonably attributed to 

permanent and enforceable emission reductions of directly emitted PM2.5 and PM2.5 

precursors and was not a result of adverse economy or unusually favorable 

meteorological conditions. 

Permanent and enforceable emission reductions

Between 2005 and 2011, emissions of directly emitted PM2.5 and PM2.5 precursors 

declined significantly as a result of control measures listed in Tables VI-5 and VI-6 of 

the Redesignation Request/Maintenance Plan. These permanent and enforceable 

reductions in directly emitted PM2.5 and PM2.5 precursors resulted in improvements in 

air quality. The majority of reductions are a result of ARB’s statewide motor vehicle 

regulations listed in Table VI-6, including NOx control programs and fleet rules to 

reduce both NOx and PM from diesel engines. 

Tables 2 through 8 and Figure 1 compare 2005 and 2011 emission year inventories, 

demonstrating that the controls listed in Tables VI-5 and VI-6 of the Redesignation 

Request/Maintenance Plan contributed to reductions in PM2.5 emissions, which in turn 

lead to reductions in PM2.5 concentrations. Table 2 summarizes 2005 and 2011 

emissions by major source category and by pollutant. Comparison of the 2005 and 

2011 inventories reveals that directly emitted PM2.5 emissions decreased 9 percent, 

NOx emissions decreased 27 percent, and SOx emissions decreased 38 percent. 

These reductions were primarily associated with mobile source categories, both on-road 

and off-road. Tables 3 through 8 show changes in these two categories.
4

Data in Tables 2 through 8 displayed to ten thousandths place to show change in 

emissions.

Table 2. Yuba City-Marysville PM2.5 Nonattainment Area 2005 and 2011 Emission 

Changes

Source Category 2005 2011 2005-2011 Reductions

tpd tpd tpd %

NOx

Stationary Sources 4.4941 4.3908 0.103 2

Areawide Sources 1.1075 1.0876 0.020 2

On-Road Mobile Sources 12.8955 8.3763 4.519 35

Other Mobile Sources 8.0414 5.4326 2.609 32

All Sectors 26.5385 19.2873 7.251 27

PM2.5

Stationary Sources 0.9812 0.8732 0.108 11

Areawide Sources 4.0302 3.8288 0.201 5

On-Road Mobile Sources 0.3557 0.2688 0.087 24

Other Mobile Sources 0.4141 0.288 0.126 30

All Sectors 5.7812 5.2588 0.522 9

SOx

Stationary Sources 0.1295 0.1254 0.004 3

Areawide Sources 0.1555 0.1478 0.008 5

On-Road Mobile Sources 0.0887 0.0246 0.064 72

Other Mobile Sources 0.2 0.056 0.144 72

All Sectors 0.5737 0.3538 0.220 38

0

5

10

15

20

25

30

NOX PM2.5 SOx

Emissions (tons per day)

Figure 1. Changes in Emissions Between 2005 and 2011

2005

2011
5

Table 3. 2005-2011 NOx Emission Changes in On-Road Mobile Source Categories

On-Road Mobile Source Categories 2005 2011 2005-2011 Reductions

tpd tpd tpd %

HEAVY HEAVY DUTY DIESEL TRUCKS (HHDV) 6.3103 3.5449 2.7654 44

LIGHT DUTY TRUCKS - 1 (LDT1) 0.2318 0.1342 0.0976 42

OTHER BUSES - MOTOR COACH - DIESEL (OBC) 0.0439 0.0266 0.0173 39

MEDIUM HEAVY DUTY DIESEL TRUCKS (MHDV) 1.1794 0.7189 0.4605 39

LIGHT DUTY PASSENGER (LDA) 1.0787 0.6751 0.4036 37

ALL OTHER BUSES - DIESEL (OBD) 0.0278 0.0185 0.0093 33

LIGHT DUTY TRUCKS - 2 (LDT2) 1.0969 0.74 0.3569 33

SCHOOL BUSES - DIESEL (SBD) 0.0662 0.0481 0.0181 27

LIGHT HEAVY DUTY GAS TRUCKS - 2 (LHDV2) 0.018 0.014 0.0040 22

MEDIUM DUTY TRUCKS (MDV) 0.9216 0.7769 0.1447 16

LIGHT HEAVY DUTY DIESEL TRUCKS - 1 (LHDV1) 1.2607 1.0665 0.1942 15

HEAVY DUTY DIESEL URBAN BUSES (UB) 0.0377 0.0325 0.0052 14

LIGHT HEAVY DUTY DIESEL TRUCKS - 2 (LHDV2) 0.1761 0.1526 0.0235 13

OTHER BUSES - GAS (OBG) 0.0094 0.0083 0.0011 12

MEDIUM HEAVY DUTY GAS TRUCKS (MHDV) 0.0507 0.0453 0.0054 11

LIGHT HEAVY DUTY GAS TRUCKS - 1 (LHDV1) 0.271 0.2487 0.0223 8

HEAVY DUTY GAS URBAN BUSES (UB) 0.009 0.0084 0.0006 7

MOTOR HOMES (MH) 0.0412 0.0385 0.0027 7

SCHOOL BUSES - GAS (SBG) 0.0034 0.0032 0.0002 6

Table 4. 2005-2011 NOx Emission Changes in ‘Other Mobile Source Categories’

Other Mobile Source Categories 2005 2011 2005-2011 Reductions

tpd tpd tpd %

OFF-ROAD EQUIPMENT 2.3139 1.1788 1.135 49

TRAINS 1.9447 1.2534 0.699 36

FARM EQUIPMENT 3.3499 2.5708 0.779 23

RECREATIONAL BOATS 0.0575 0.0536 0.004 7

Table 5. 2005-2011 PM2.5 Emission Changes in On-Road Mobile Source Categories

On-Road Mobile Source Categories 2005 2011 2005-2011 Reductions

tpd tpd tpd %

MEDIUM HEAVY DUTY DIESEL TRUCKS (MHDV) 0.0459 0.028 0.0179 39

ALL OTHER BUSES - DIESEL (OBD) 0.0013 0.0008 0.0005 38

HEAVY HEAVY DUTY DIESEL TRUCKS (HHDV) 0.1941 0.1273 0.0668 34

OTHER BUSES - MOTOR COACH - DIESEL (OBC) 0.0012 0.0008 0.0004 33

SCHOOL BUSES - DIESEL (SBD) 0.0041 0.0029 0.0012 29

LIGHT HEAVY DUTY DIESEL TRUCKS - 1 (LHDV1) 0.0187 0.0175 0.0012 6

MEDIUM DUTY TRUCKS (MDV) 0.0181 0.0174 0.0007 4
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Table 6. 2005-2011 PM2.5 Emission Changes in ‘Other Mobile Source Categories’

Other Mobile Sources 2005 2011 2005-2011 Reductions

tpd tpd tpd %

OFF-ROAD EQUIPMENT 0.1135 0.0586 0.055 48

TRAINS 0.0517 0.0323 0.019 38

FARM EQUIPMENT 0.1903 0.1424 0.048 25

RECREATIONAL BOATS 0.0181 0.0145 0.004 20

OFF-ROAD RECREATIONAL VEHICLES 0.0015 0.0012 <0.001 20

Table 7. 2005-2011 SOx Emission Changes in On-Road Mobile Source Categories

On-Road Mobile Source Categories 2005 2011 2005-2011 Reductions

tpd tpd tpd %

SCHOOL BUSES - DIESEL (SBD) 0.0005 <0.0001 >0.0004 >90

OTHER BUSES - MOTOR COACH - DIESEL (OBC) 0.0003 <0.0001 >0.0002 >90

ALL OTHER BUSES - DIESEL (OBD) 0.0003 <0.0001 >0.0002 >90

MOTOR HOMES (MH) 0.0002 <0.0001 >0.0001 >90

MEDIUM HEAVY DUTY DIESEL TRUCKS (MHDV) 0.0101 0.0009 0.0092 91

HEAVY HEAVY DUTY DIESEL TRUCKS (HHDV) 0.0511 0.0048 0.0463 91

LIGHT HEAVY DUTY DIESEL TRUCKS - 1 (LHDV1) 0.009 0.0010 0.0080 89

LIGHT HEAVY DUTY DIESEL TRUCKS - 2 (LHDV2) 0.0013 0.0002 0.0011 85

HEAVY DUTY DIESEL URBAN BUSES (UB) 0.0005 0.0001 0.0004 80

Table 8. 2005-2011 SOx Emission Changes in ‘Other Mobile Source Categories’

Other Mobile Source Categories 2005 2011 2005-2011 Reductions

tpd tpd tpd %

TRAINS 0.1113 0.0010 0.110 99

OFF-ROAD EQUIPMENT 0.0105 0.0003 0.010 97

FARM EQUIPMENT 0.0263 0.0028 0.024 89

Role of economic conditions and meteorology

The improvement in air quality was not due to a decline in the economy. On the 

contrary, the economy grew about 20 percent between 2004 and 2012. Figure 2 shows 

Gross Domestic Product (GDP) for the Yuba City-Marysville Metropolitan Statistical 

Area. The increase in GDP between 2004 and 2012 is an indicator of economic 

progress.
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Data source: U.S. Department of Commerce, Bureau of Economic Analysis

In addition, the air quality improvement was not due to favorable meteorological 

conditions. During the five year period, when the design values were below the 

standard, the area experienced a variety of meteorological conditions. For example,

2011 was extremely conducive to PM2.5 pollution, including a stagnation period that 

persisted for over 20 days. Despite this, 2011 and 2012 design values are significantly 

below the standard. The standard meteorological parameters, including annual average 

temperature and precipitation, were similar during the three recent years showing 

attainment (2010-2012) as well as the 2004-2006 nonattainment period (Table 9).

Table 9. Average Temperature and Precipitation

Year Avg Temp (

o

F) Avg Precipitation (in/year)

2004 62.6 20

2005 62.6 26

2006 62.6 20

2007 62.6 12

2008 62.6 16

2009 66.2 17

2010 62.6 23

2011 59.0 20

2012 62.6 25

2004-2006 Avg 62.6 22

2010-2012 Avg 62.6 23

0

500

1000

1500

2000

2500

3000

3500

4000

4500

5000

2004 2005 2006 2007 2008 2009 2010 2011 2012

Millions U.S. Dollars

Figure 2. GDP for All Industry
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IV. DISCUSSION OF FUTURE YEAR COMPOSITION USED IN CALCULATION OF 

THE 2024 DESIGN VALUE

In the Redesignation Request/Maintenance Plan, the District assumed that the PM2.5 

composition on high concentration days did not change between 2004-2006 and 2011. 

Due to the nature of the PM2.5 problem in the Yuba City-Marysville Area and the form 

of the standard, it is appropriate to assume that composition would not change 

significantly. Furthermore, control programs targeting all key contributors to PM2.5 

mass lead to fairly equivalent reduction in key components.

Chemical composition data are not routinely collected at the Yuba City monitor. The 

only chemical composition data available for this area are 2004-2006 data analyzed by

U.S. EPA to support the initial designations. Staff expect that despite a significant 

decline in emissions between 2005 and 2011, the chemical composition on a typical 

exceedance day would not change significantly. The meteorological phenomenon 

leading to high PM2.5 concentrations is the same today as it was in 2005. Under 

stagnant winter weather, elevated concentrations are due to the formation of secondary 

pollutants and the accumulation of primary-emitted PM2.5. The declines in emissions 

reduced the frequency and magnitude of high concentration day events, but are

expected to have little impact on exceedance day composition. 

In addition, control programs targeted all key contributors to the PM2.5 mass. The two 

largest contributors to PM2.5 mass in the Yuba City-Marysville area are wood burning 

and ammonium nitrate. Concurrent reductions in both directly emitted PM2.5 and NOx 

emission that contribute to these components. Therefore composition remains the 

same despite the decrease in PM2.5 levels. 

Figures 3 and 4 show the changes in chemical composition on a typical exceedance at 

the Sacramento-T Street site (the closest site with chemical composition data and 

similar meteorological conditions) between 2004-2006 and 2010-2012. Despite the 

decrease in emissions over the years the composition in 2010-2012 is very similar to 

that in 2004-2006. 
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IV. CONTINGENCY PLAN

U.S. EPA requested additional clarification from the District related to timing associated 

with the contingency plan if the area were to fall out of attainment. On 

December 19, 2013, the District clarified several aspects of the contingency measure 

commitment in a letter to U.S. EPA and ARB. The District letter is included in 

Appendix A.

V. STAFF RECOMMENDATION

The Minor Updates to Yuba City-Marysville PM2.5 Maintenance Plan and 

Redesignation Request include additional supporting information and analysis as 

requested by U.S. EPA to facilitate their approval and redesignation to attainment for 

the PM2.5 standard. ARB staff recommends that the Board adopt the Minor Updates as 

a revision to the California SIP for submittal to U.S. EPA. 

Figure 3. Sacramento-T Street 

(2004-2006)

Total 

Carbonaceous 

Mass

46%

Ammonium 

Nitrate

47%

Passive 1% Crustal 1%

Ammonium Sulfate 5%

Figure 4. Sacramento-T Street 

(2010-2012)

Total 

Carbonaceous 

Mass

41%

Ammonium 

Nitrate

51%

Passive 1% Crustal 1%

Ammonium Sulfate 6%
1

Appendix A

Feather River Air Quality Management District Letter