Air Resources Board 

Mary D. Nichols, Chairman 

1001 1 Street P.O. Box 281 5 

Linda S. Adams Sacramento, California 95812 www.arb.ca.gov Edmund G. Brown Jr. 

Acting Secretary for Governor 

Environmental Protection 

May 18,201 1 

Elizabeth Adams, Deputy Director 

Air Division, Region 9 

U.S. Environmental Protection Agency 

75 Hawthorne Street 

San Francisco, California 941 05 

Dear Ms. Adams: 

On April 28,201 1, the Air Resources Board (ARB or Board) approved for adoption a 

revision to California's State Implementation Plan (SIP) for the federal particulate matter 

standard (PM2.5). Under separate cover, ARB is formally submitting the SIP revision to 

the U.S. Environmental Protection Agency (U.S. EPA). Following the Board's April 

action, U.S. EPA staff requested additional explanation of information contained in the 

SIP revision. In response to this request, ARB staff is providing the following: 

Attachment 1: lnformation that shows the emission inventory relationships among 

the detailed information in specific appendices: Appendix C, "Reasonable 

Further Progress Tables"; Appendix Dl "Transportation Conformity Budgets"; and 

the detailed methodology included in Appendix El "Additional Documentation." 

lnformation on how these methodologies affect base year emissions is also 

discussed. 

Attachment 2: lnformation on attainment year contingency estimates contained in 

the adopted SIP revision, including the emission reductions between 2014 and 

2015 that would be used for attainment year contingency. 

Attachment 3: lnformation on inter-pollutant trading ratios that depicts the relative 

effectiveness of reductions in different precursors contributing to ambient PM2.5 

levels in the San Joaquin Valley Air Basin and the South Coast Air Basin. 

Attachment 4: lnformation on what measures are included in the motor vehicle 

emissions budget calculations, with comparisons of line item adjustments to 

measures used in previous transportation conformity budgets with line item 

The energy challenge facing California is real. Every Californian needs to take immediate action to reduce energy consumption. 

For a list of simple ways you can reduce demand and cut your energy costs, see our website: htt~://w.arb.ca.aov. 

California Environmental Protection Agency 

Printed on Recycled Paper 
Elizabeth Adams 

May 18, 201 1 

Page 2 

adjustments used in the Transportation Conformity Budgets contained in the 

201 1 SIP revision. 

Attachment 5: Description of irr~provements to California's Motor Vehicle 

Emissions Inspection and Maintenance (IIM) Program that will improve the 

effectiveness of California's IIM program, beginning in January 2013. 

If you have any questions, please call me at (916) 322-2739, or have your staff contact 

Mr. Douglas Ito, Chief, Air Quality and Transportation Planning Branch, at 

(91 6) 322-0285. 

Sincerely, 

,WT 

~ynn Terry 

Deputy ~xecutive Officer 

Attachments 

cc: (WIO attachments) 

Mr. Douglas Ito, Ct-lief 

Air Quality and Transportation Planning Branch 

Planning and Technical Support Division 
Attachment 1 

Emissions Inventory Discussion 

Appendix E of the ARB staff report describes the inventory improvements ARB made as 

a part of rulemaking to implement the SIP. The recession does not impact the SIP base 

year modeling since both regions used a base year prior to the recession. The base 

year irr~pacts from inventory improvements for the South Coast Air Basin (2002) and the 

San Joaquin Valley Air Basin (2005) reflected in Tables SC-2002 and SJV-2005, while 

critical to rulemaking, are small relative to the overall inventory. Small changes in base 

year emissions would not substantially change the fundamental relationship between 

emissions and nieasured air quality in the base year modeling. 

Tables SC-2009, SC-2012, SC-2014, SJV-2009, SJV-2012, and SJV-2014 show the 

relationships among the detailed information in Appendix C: Reasonable Further 

Progress Tables, Appendix D: Transportation Conformity Budgets and the detailed 

methodology included in Appendix E: Additional Documentation. 
Attachment 1 

Table SC-2002 

South Coast Air Basin 

2002 

(Annual Average, tpd) 

NOx Equivalent 

SIP 

Stationary and Areawide 1144 

On-road Mobile 1012 

Off-road Mobile 1059 

Total Inventory 3216 

NOx 

Category 

Stationary and Areawide 

On-road Mobile 

Off-road Mobile 

Total Inventory 

PM2.5 

Current 

--- Estimate 

1144 

1095 

1069 

3292 

Category 

Stationary and Areawide 

On-road Mobile 

Off-road Mobile 

Total Inventory 

sox 

% Change 

0% 

8% 

1% 

2% 

SIP 

93 

628 

372 

1093 

Category 

Stationary and Areawide 

On-road Mobile 

Off-road Mobile 

Total Inventory 

ROG 

Current 

Estimate 

93 

685 

269 

1046 

SIP 

60 

18 

21 

99 

Category 

Stationary and Areawide 

On-road Mobile 

Off-road Mobile 

Total Inventory 

Current 

Estimate 

60 

19 

15 

94 

SIP 

2 2 

4 

27 

53 

Current 

Estimate 

22 

5 

39 

I 65 

SIP 

303 

361 

180 

844 

Current 

Estimate 

303 

362 

162 

827 
Attachment 1 

San Joaquin Valley 

2005 

(Annual Average, tpd) 

NOx Equivalent 

Category 

Stationary and Areawide 

On-road Mobile I 

Off-road Mobile 

Total Inventory 

NOx 

Category 

Stationary and Areawide 

On-road Mobile 

Off-road Mobile 

Total Inventory 

PM2.5 

sox 

% Change 

I 0% 

-9% 

-12% 

-4% 

SIP Current 

Estimate 

SIP 1 Current 

Estimate 

Current 

Estimate 

65 

- 10 

8 

8 2 

Category SIP 

Category 

Stationary and Areawide 

On-road Mobile 

Off-road Mobile 

Total Inventory 

96 

51 

28 

176 

94 

Stationary and Areawide -- 

On-road Mobile 

Off-road Mobile 

Total Inventory 

9 6 

47 

25 

168 

94 

65 

12 

9 

86 

SIP 

21 

3 

2 

2 6 

Current 

Estimate 

2 1 

2 

2 

2 6 

328 

154 

575 

315 

132 

540 
Attachment 1 

Table SC-2009 

South Coast Air Basin 

2009 

(Annual Average, tpd) 

NOx 

PM2.5 

Category 

2009 

Remaining 

Emissions 

84 

397 

198 

678 

1 

677 

I 

Stationary and Areawide 

On-road Mobile 

Off-road Mobile 

Total Inventory 

sox 

Category 

Stationary and Areawide 

On-road Mobile 

Off-road Mobile 

Total Inventory 

ROG 

SIP 

84 

413 

326 

823 

62 

18 

18 

97 

2009 

Remaining 

Emissions 

22 

2 

19 

43 

0 

43 

Category 

Category 

Stationary and Areawide 

On-road Mobile 

Off-road Mobile 

Total Inventory 

Reductions from Adopted Local Measures 

Estimated Remaining Emissions 

62 

17 

11 

89 

Reductions from Adopted Local Measures 

Estimated Remaining Emissions 

Stationary and Areawide 

On-road Mobile 

Off-road ~obile . 

Total Inventory 

0 

89 - 

22 

2 

21 

45 

1 2009 

Reductions from Adopted Local Measures 

Estimated Remaining Emissions 

SIP 

241 

196 

147 

584 

Reductions from Adopted Local Measures 

Estimated Remaining Emissions 

Remaining 

Emissions 

241 

192 

131 

564 

0 

563 
Attachment 1 

Table SC-2012 

South Coast Air Basin 

2012 

(Annual Average, tpd) 

NOx 

Category 

Stationary and Areawide 

On-road Mobile 

Off-road Mobile 

Total Inventory 

PM2.5 

Category 1 SIP 1 Re2:ing 

Emissions 

sox 

1 2012 

SIP Remaining 

63 

16 

10 

89 

1 

88 

Stationary and Areawide 

On-road Mobile 

Off-road Mobile 

Total Inventory 

Category 

Stationary and Areawide -- 

On-road Mobile 

Off-road Mobile 

Total Inventory 

ROC 1 2012 

76 

337 

297 

710 

Reductions from Adopted Local Measures 

Estimated Remaining Emissions 

63 

17 

17 

97 

Emissions 

76 

326 

184 

586 

5 

582 

Reductions from Adopted Local Measures 

Estimated Remaining Emissions 

SIP 

17 

2 

2 3 

43 

Remaining 

Emissions 

247 

158 

121 

525 

11 

514 

Category 

2012 

Remaining 

Emissions 

17 

2 

6 

26 

Reductions from Adopted Local Measures 

Estimated Remaining Emissions 

Stationary and Areawide 

On-road Mobile 

Off-road Mobile 

Total Inventory 

0 

26 

247 I 162 

134 

542 

Reductions from Adopted Local Measures 

Estimated Remaining Emissions 
Attachment 1 

Table SC-2014 

South Coast Air Basin 

2014 

(Annual Average, tpd) 

NOx 

PM2.5 

2014 

Remaining 

Emissions 

75 

291 

176 

542 

8 

534 

Category 

Stationary and Areawide 

On-road Mobile 

Off-road Mobile 

Total Inventory 

sox 

SIP 

7 5 

292 

285 

653 

2014 

Remaining 

Emissions 

64 

14 

10 

88 

1 

87 

Category 

Stationary and Areawide 

On-road Mobile 

Off-road Mobile 

Total Inventory 

Category 

Stationary and Areawide 

On-road Mobile 

Off-road Mobile 

Total Inventory 

ROG 

Reductions from Adopted Local Measures 

Estimated Remaining Emissions 

SIP 

64 

17 

16 

97 

Reductions from Adopted Local Measures 

Estimated Remaining Emissions 

SIP 

2014 

Remaining 

Emissions 

251 

136 

116 

503 

14 

489 

Category 

Stationary and Areawide 

On-road Mobile 

Off-road Mobile 

Total Inventory 

2014 

Remaining 

Emissions 

Reductions from Adopted Local Measures 

Estimated Remaining Emissions 

SIP 

251 

145 

127 

524 

4 

20 

Reductions from Adopted Local Measures 

Estimated Remaining Emissions 

17 

2 

2 5 

45 

17 

2 

5 

24 
Attachment 1 

San Joaquin Valley 

2009 

(Annual Average, tpd) 

NOx 

PM2.5 

* The San Joaquin Valley Reasonable Further Progress tables in Appendix C are consistent with the 

remaining emissions identified in the New 2009 Baseline Column. 

Category SIP 

sox 

New 2009 2009 Remaining 

Stationary and Areawide 

On-road Mobile 

Off-road Mobile 

Total Inventory 

2009 Remaining 

Emissions 

6 1 

7 

6 

75 

SIP ~ New 2009 Category 

Category 

Stationary and Areawide 

On-road Mobile 

Off-road Mobile 

Total Inventory 

Baseline* 

74 

208 

102 

384 

74 

297 

130 

501 

Stationary and Areawide - 

On-road Mobile 

---- 

Off-road Mobile 

Total Inventory 

Emissions 

208 

74 - 

102 

384 

Reductions from Adopted Local Measures 

Estimated Remaining Emissions 

Reductions from Adopted Local Measures 

Estimated Remaining Emissions 

Baseline* 

2009 Remaining 

Emissions 

2 2 

1 

SIP 1 New 2009 

Baseline* 

Reductions from Adopted Local Measures 

Estimated Remaining Emissions 

2 

61 

11 

8 

2 

2 2 

1 

381 

6 1 

7 I 

6 

73 

2 2 

1 

1 

23 

0 

381 

80 I 75 

73 

23 

1 

2 3 

23 

1 

23 
Attachment 1 

San Joaquin Valley 

201 2 

(Annual Average, tpd) 

NOx 

PM2.5 

* The San Joaquin Valley Reasonable Further Progress tables in Appendix C are consistent with the 

remaining emisiions identified in the New 2012 Baseline Column. 

Category 

Stationary and Areawide 

On-road Mobile** 

Off-road Mobile 

Total Inventory 

Category 

Stationary and Areawide 

On-road Mobile** 

Off-road Mobile 

Total Inventory 

sox . 

** The San Joaquin Valley Transportation Conformity Budgets in Appendix D are consistent with the 

On-road Mobile source estimated emission values in the 2012 Remaining Emissions column. 

New 2012 

Baseline* 

70 

182 

88 

340 

SIP 

70 

244 

111 

424 

2012 Remaining 

Emissions 

70 

180 

88 

338 

Reductions from Adopted Local Measures 

Estimated Remaining Emissions 

SIP 

60 

10 

7 

77 

Category 

Stationary and Areawide 

On-road Mobile 

Off-road Mobile 

Total Inventory 

Reductions from Adopted Local Measures 

Estimated Remaining Emissions 

New 2012 

Baseline* 

22 

1 

1 

24 

SIP 

2 2 

1 

1 

24 

12 

New 2012 2012 Remaining 

2012 Remaining 

Emissions 

2 2 

1 

1 

24 

Reductions from Adopted Local Measures 

Estimated Remaining Emissions 

328 

Baseline* 

60 

7 

6 

74 

S 

326 

Emissions 

60 

7 

6 

73 

69 

3 

68 

20 20 
Attachment 1 

San Joaquin Valley 

2014 

(Annual Average, tpd) 

NOx 

Category 

Stationary and Areawide 

On-road Mobile* 

Off-road Mobile 

Total Inventory 

PM2.5 

* The San Joaquin Valley Transportation Conformity Budgets in Appendix D are consistent with the Onroad Mobile source estimated emission values in the 2014 Remaining Emissions column. 

sox 

SIP 

67 

207 

102 

376 

2014 Remaining 

Emissions 

60 

5 

6 

71 

Category 

Stationary and Areawide 

On-road Mobile* 

Off-road Mobile 

Total Inventory 

Reductions from Adopted Local Measures 

Estimated Remaining Emissions 

' SIP 

New 2014 

Baseline 

67 

161 

84 

3 13 

Reductions from Adopted Local Measures 

Estimated Remaining Emissions 

SIP 

60 

9 

7 

75 

New 2014 

Baseline 

2 3 

1 

1 

24 

Category 

Stationary and Areawide 

On-road Mobile 

Off-road Mobile 

Total Inventory 

2014 Remaining 

Emissions 

67 

159 

84 

311 

13 

New 2014 

Baseline 

60 

7 

6 

7 2 

2014 Remaining 

Emissions 

23 

1 

1 

24 

23 

1 

1 

24 

300 

5 

Reductions from Adopted Local Measures 

Estimated Remaining Emissions 

298 

67 

4 

65 

21 21 
Attachment 2 

Attainment Year Contingency Estimates 

For the 2014 attainment year, the additional emission reductions accrued in 201 5 are 

relied upon to meet the contingency requirements for both the San Joaquin Valley and 

the South Coast. 'The contingency estimates were calculated by taking into account 

baseline emission reductions that occur between 2014 and 201 5 as shown in the 2007 

State Strategy emission inventory, as well as emission reductions from recently adopted 

regulations and recession adjustments. 

Table I 

San Joaquin Valley PM2.5 Attainment Year Contingency 

I Contingency (tpd) 

Table 2 

'lux 

PM2.5 

sox 

L I 

0 

3 

South Coast PM2.5 Attainment Year Contingency 

NOx 

PM2.5 

sox 

ROG 

Contingency (tpd) 

24 

0 

0 

13 
Attachment 3 

Precursor Effectiveness 

In order to understand the relative effectiveness of reductions in different precursors 

contributing to ambient PM2.5, staff of the Air Resources Board (ARB) and the South 

Coast Air Quality Management District (SCAQMD) conducted air quality modeling 

sensitivity runs using the modeling conducted for the attainment demonstrations. These 

relative effectiveness ratios were used to guide control strategy development as well as 

to normalize the benefits of multiple precursors so they can be reflected in terms of a 

single equivalent precursor. This method also provides a uniform metric for tracking 

progress relative to the attainment emissions targets. Documentation on the 

methodologies used for calculating the effectiveness ratios in each area is provided 

below. 

South Coast 

A description of the methodology used by SCAQMD staff is provided in Appendix C of 

ARB'S staff report on the SCAQMD 2007 State Implementation Plan which can be found 

at: 

San Joaquin Valley 

In order to evaluate precursor effectiveness, ARB staff focused on the response in the 

Bakersfield metropolitan area where the highest PM2.5 concentrations in the San 

Joaquin Valley occur. Staff conducted two grid-based modeling sensitivity runs where 

the NOx and primary PM2.5 emissions were reduced, one at a time, by 10% relative to 

the future-year modeled attainment scenario. From these sensitivity runs we calculated 

a future year modeled design value reflecting the further 10% emission reduction 

assumptions. The difference between the attainment scenario (before 10% reduction in 

emissions) and adjusted (after 10% reduction in emissions) design values were then 

compared. Table 1 shows results for NOx and primary PM2.5 emission reductions as 

well as the efficacy of reducing primary PM2.5 relative to that for NOx. 

The lS' column of Table 1 lists the Bakersfield area monitoring sites and the 2" column 

contains the monitored 2006 design value for those sites. The 3rd column contains the 

2014 modeled design values taking into account all of the reductions in the attainment 

strategy. The 4Ih and 5'h columns list the adjusted 2014 design values with additional 

10% emissions reductions for NOx, and primary PM2.5, respectively. The 6'h column 

lists the effectiveness of controlling primary PM2.5 relative to that of controlling NOx. This 

analysis showed that controlling primary PM2.5 is approximately nine times more 

effective than controlling NOx based on the average across the three Bakersfield area 

sites. 
Attachment 3 

The precursor effectiveness values were calculated by determining the difference 

between the modeled 2014 attainment design value (3rd column) and the design value 

of the sensitivity run (4th or 5th col~~mns). This difference was then divided by the 

tonnage of each precursor corresponding to a 10% domain-wide reduction in emissions 

to develop the respective precursor effectiveness ratios. 'The PM2.5 effectiveness value 

was then divided by the NOx effectiveness value to determine a relative ratio (6th 

column). 

Table 1: The effectiveness of precursor controls on the 2014 design value. 

Site Measured 

2006 

Design Value 

(uglm3) 

Modeled 

2014 

Design Value 

With 

SIP 

Attainment 

Strategy 

(uglm3) 

Modeled 

2014 

Design Value 

With 

Additional 

10% NOx 

Reduction 

(uglm3) 

Modeled 

2014 

Design Value 

With 

Additional 

10% PM2.5 

Reduction 

(uglm3) 

Effectiveness 

Relative to 

NOx 

Site 1 

(Bakersfield-California 

Site 2 

(Bakersfield-Planz) 

Site 3 

(Bakersfield-Golden) 

18.5 

18.9 

18.6 

14.3 

14.7 

14.4 

- 

14.1 

14.6 

14.2 

13.6 

14.0 

13.7 

8.7 

9.3 

8.6 
Attachment 4 

New Budqets 

EMFAC2007 Baseline, covering 201 2 and 2014 for South Coast and San Joaquin 

Valley 

Line ltem Adjustments to Baseline for Measures 

Adopted Prior to December 2006 

(Referred to as "Adjustments to Baseline" in Budgets, 

adjustments included in applicable years) 

South Coast and San Joaquin Vallev 

AB 1493 GHG Standards 

On-Road Portion of Carl Moyer Program 

San Joaquin Vallev Onlv 

District Rule 931 0 - School Buses 

Adjustments Now Included in New Heavy Duty Diesel Truck Model 

(Included in "State Strategy Adjustments" in Budgets, 

adjustments included in applicable years) 

South Coast and San Joaquin Vallev 

New HDDT Inventory 

HDDT Recession Impacts 

HDDT In-Use Rule 

HDDT Chip Re-flash 

HDDT Public Fleet and Solid Waste Rules 

HDDT Idling Rule 

Line ltem Adjustments for Adopted SIP Measures 

(Included in "State Strategy Adjustments" in Budgets, 

adjustments included in applicable years) 

South Coast and San Joaquin Vallev 

Smog Check Improvements (Low Pressure Evap, Cutpoints, Lt. 

Duty Diesels, Smoke Test) 

Reformulated Gasoline 

South Coast Or~ly 

AB 923 High Emitter 

San Joa~uin Vallev Onlv 

Indirect Source Rule 
Attachment 4 

Line ltem Adjustments in PM2.5 Conformity Budgets for 

South Coast and San Joaquin Valley 

Previous Budgets 

EMFAC2007 Baseline, covering 2009,2012,2014, 2023 and 2030 for South Coast and 

2009,201 2 and 2014 for San Joaquin Valley 

Line ltem Adjustments To Baseline For Measures 

Adopted Prior To December 2006 

(Referred to as "Adjustments to Baseline" in Budgets, 

adjustments included in applicable years) 

South Coast and San Joaquin Valley 

Heavy Duty Diesel Truck (HDDT) Chip Reflash 

HDDT Public Fleet and Solid Waste Rules 

HDDT Idling Rule 

AB 1493 GHG Standards 

On-Road Portion of Carl Moyer Program 

San Joaquin Vallev Onlv 

District Rule 9310 - School Buses 

Line ltem Adjustments for Proposed SIP Measures 

(Referred to as "State Strategy Reductions" in Budgets, 

adjustments included in applicable years) 

South Coast and San Joaquin Valley 

All Smog Check Improvements (Low Pressure Evap, Cutpoints, 

Annual Insp. for Older, Annual Insp. for High Mileage, 

Motorcycles, Lt. Duty Diesels, Smoke Test) 

HDDT In-Use Rule 

Reformulated Gasoline 

Expanded Vehicle Retirement 

South Coast Onlv 

A6 923 High Emitter 

San Joaquin Vallev Only 

Indirect Source Rule 
Attachment 5 

lmprovements to California's 

lnspection and Maintenance Program 

California took a major step forward in improving the effectiveness of the 

Enhanced Vehicle lnspection and Maintenance (IIM) prog'ram with the recent 

passage of Assembly Bill 2289 (Chapter 258, Statutes of 2010). 

This bill requires that the Bureau of Automotive Repair identify the specific Smog 

Check stations and individual technicians that are doing the best job identifying 

dirty vehicles and repairing them. The Station and Technician Achievement 

Rating program, or STAR, will start in January 201 3. After that, all vehicles older 

than model year 1999, can only be inspected by high performing technicians at 

STAR Certified Stations. 

For all vehicles model year 2000 and newer, California will test the on-board 

diagnostic computer systems, commonly referred to as OBD-only testing, in 

place of tailpipe testing. With this, California will join the 22 other states that 

perform OBD-only testing on late model vehicles. This will greatly improve the 

accuracy and quality of inspections on late model vehicles by taking advantage 

of the advanced technology, real-time data transfer, and state-of-the-art antifraud provisions built into OBD II equipped vehicles. 

Other improvements to California's I/M program will include revisions to the 

enforcement fine structure to improve industry compliance, mandated annual 

reporting, and support for technician training programs through community 

colleges and private training entities. 

Comparison of lmprovements to California's Enhanced 

IIM Proaram 

Existing IIM Program 

Gold Shield Test and Repair 

Test and Repair 

Vehicles OnlyIGold Shield stations. 

lmprovements 

STAR certified stations (test-only 

and test and repair) 

Non-STAR certified stations (testonly and test and repair) 

All model year 1999 and older 

vehicles directed to STAR stations. 

Model year 2000 and newer 

receive OBD-onlv ins~ections. 

Program 

Performance 

inspections. 

I 

USEPA approved the enhanced STAR performance criteria are 

program in 2009 as a California SIP more stringent than Gold Shield. 

revision based on modeling that 

showed the enhanced program 

The USEPA acknowledges the 

effectiveness of OBD II inspections meets or exceeds the federal by providing full emission credits to 

performance standard. IIM programs with OBD-Only