April 26, 2007 72 

4. PM2.5 Attainment in the South Coast 

South Coast air district modeling conducted in early 2007 indicated that the 

adopted and new SIP measures in the Proposed State Strategy would bring 

South Coast PM2.5 levels down to 15.7 ug/m3 by 2014. While this is tremendous 

progress, it is still 0.7 ug/m3 above the standard. The South Coast air district also 

used air quality modeling to identify additional reductions the district believes are 

needed beyond those in the State Strategy. The South Coast air district’s 

emission reduction targets and the additional reductions needed to meet the 

district’s targets are shown in the table below. 

South Coast Air District Proposed Attainment Demonstration 

NOx ROG SOx 

Direct 

PM2.5 

Emission Reductions 

Needed 203 59 24 14 

Reductions from New 

Measures 129 52 23 11 

Additional Reductions 

Needed to Meet South 

Coast Targets 

74 7 1 3

However, the additional large NOx reductions called for by the South Coast air 

district is just one potential way to close the 0.7 ug/ m3 gap. This chapter 

explores alternatives for attaining the federal PM2.5 standard by the 2015 

deadline. It starts by characterizing the PM2.5 problem to give context to the 

complexities of PM2.5 sources, formation, and control. It looks at closing the gap 

through aggressive direct particulate matter reductions: local measures to 

decrease emissions from residential wood burning, restaurant cooking, and 

fugitive dust. It analyzes the South Coast air district staff’s ideas for mobile 

source measures to see if it is feasible to get the additional NOx emission 

reductions called for by the South Coast air district. Finally, it makes 

recommendations for Board consideration regarding actions to meet the South 

Coast PM2.5 challenge. 

Nature of PM2.5 Pollution

Assessing how emissions affect the air we breathe is more complicated for 

PM2.5 than it is for ozone. While ozone has just two key precursors, PM2.5 is a 

complex mix of particles, some formed in the air and some emitted directly. 

PM2.5 can be formed in the air from the reaction of the precursor gases – 

primarily NOx, SOx, ROG, and ammonia. The resulting particles are referred to 

as secondary PM2.5. The two main components of secondary PM2.5 in the 

South Coast are ammonium nitrate and ammonium sulfate, which are formed 

when NOx and SOx interact with ammonia. PM2.5 can also be directly emitted 
April 26, 2007 73 

into the air in forms such as smoke, dust, and soot. The main contributors of 

directly emitted PM2.5 are organic and elemental carbon, emitted from sources 

like residential wood burning, commercial cooking, gas and diesel engines, and 

airborne soil (dust). 

Special monitoring and analytical tools are used to determine which sources 

contribute to PM2.5 levels in a specific area and how much. Because the PM2.5 

problem can have localized as well as regional components, strategies that focus 

on the major contributors of PM2.5 in specific areas can be critical to meeting air 

quality standards. 

Secondary 

PM2.5

Direct PM 

2.5

Aug. 2003 - Dec. 2005 

Average Source Contribution in LA-North Main

Aug. 2003-Dec. 2005 

Average Source Contribution in Rubidoux

Direct 

PM2.5 

Secondary 

PM2.5

The figure above shows the results of an ARB staff source attribution analysis of 

data from PM2.5 captured on filters at two monitoring sites in the South Coast: 

the Los Angeles-North Main (LA-North Main) site, located in an industrial area 

1.5 miles northeast of downtown Los Angeles, and the Riverside-Rubidoux 

(Rubidoux) monitoring site in western Riverside County. The analysis shows that 

secondary PM2.5 caused primarily by NOx and SOx emissions contributes over 

half of the PM2.5 pollution in both areas. This highlights the need for substantial 

emission reductions from mobile sources, which are the main sources of NOx 

and SOx. But directly emitted particles also contribute a very large portion of 

PM2.5 pollution. A good portion of directly emitted particles are from sources 

other than motor vehicles. 

PM2.5 Emission Trends – Steadily Getting Better

Emission control measures adopted to date, especially mobile source controls, 

have resulted in tremendous progress in reducing PM2.5 in the South Coast. Air 

quality data collected since initial PM2.5 monitoring began in 1990 show that 

between 1990 and 1998, PM2.5 annual average concentrations dropped by 30 to 

40 percent throughout the air basin. PM2.5 annual average concentrations have 

dropped a further 20 to 30 percent since the official regulatory monitoring 

program for the federal PM2.5 standard began in 1999. 
April 26, 2007 74 

The figure below shows that all monitors in the South Coast Air Basin have 

recorded a significant decrease in annual average design values.1 The peak 

annual average design value of 30 ug/m3 in 2001, twice the level of the federal 

standard, dropped to 20.8 ug/m3

 in 2006. The South Coast now attains the 

federal 24-hour standard of 65 ug/ m3, further demonstrating the progress made 

in reducing particulate pollution in the region. 

Three Year Annual Average PM2.5 Design Values

0

5

10

15

20

25

30

35

2001 2002 2003 2004 2005 2006

Year

Concentrations (ug/m3)

Fontana-Arrow Highw ay

Los Angeles-North Main

Street

Lynw ood

North Long Beach

Ontario-1408 Francis Street

Riverside-Magnolia

Riverside-Rubidoux

San Bernardino-4th Street

The graph below shows that the primary reason for the improvement is the drop 

in NOx levels. The graph shows the large drop in NOx concentrations measured 

in the air, and the strong relationship between that drop and the reduction in the 

measured secondary ammonium nitrate component of PM2.5. The basin’s 

measured ambient NOx average has decreased 25 percent since 2001, while 

PM2.5 ammonium nitrate concentrations decreased by 40 percent. 

PM2.5 Ammonium Nitrate at Rubidoux

Compared to Basin Average NOx

0.0

2.0

4.0

6.0

8.0

10.0

12.0

14.0

16.0

18.0

2001 2002 2003 2004 2005

Ammonium Nitrate (ug/m 3

)

0.0

1.0

2.0

3.0

4.0

5.0

6.0

7.0

NOx (pphm)

Ammonium Nitrate

NOx

 

1

 Design values are based on the arithmetic mean of measured levels averaged over three years. 

So 2001 values are based on average levels from 1999, 2000, and 2001. 
April 26, 2007 75 

The PM2.5 Challenge

PM2.5 progress over the last 15 years shows a trend suggesting that attainment 

of the standard by 2015 with the proposed State Strategy is possible. The chart 

below illustrates that progress from 2001 to 2006 gets PM2.5 levels almost twothirds of the way to meeting the 15 ug/m3 standard, from 30 ug/m3

 to 20.8 ug/m3. 

South Coast PM2.5 Air Quality and Modeling 

(Rubidoux)

0

5

10

15

20

25

30

35

2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015

Concentrations (ug/m3)

PM2.5 Target

Measured

Measured

Modeled

0.7ug/m3 gap

However, South Coast air district modeling shows a less positive picture. The 

South Coast air district’s most recent modeling, released in February 2007, 

predicts that although we will get 95 percent of the way to the 15.0 ug/m3

 target 

by 2014 with adopted and proposed new SIP measures, we will fall just short, 

reaching only15.7 ug/m3. The model’s prediction that PM2.5 progress will slow 

down, as indicated by the trend line in the chart above, is somewhat surprising 

considering that emissions, specifically NOx emissions, are projected to drop by 

about 6 percent per year from 2006 to 2014 – about twice as fast as they fell 

between 2001 and 2006. 

Even more surprising were the South Coast air district modeling results indicating 

that it would take over 70 tons per day of additional NOx reductions to bridge the 

0.7 ug/m3 gap. Although measured data show a much greater response to past 

emission reductions than the model shows with the future reductions, federal 

rules require the use of models in SIPs. If a NOx-focused approach is used to 

close the 0.7 ug/m3

 gap, as the South Coast district advocates, much larger NOx 

reductions than those proposed in the State Strategy will be needed. 
April 26, 2007 76 

Closing the Gap with Direct PM2.5 Reductions

The previous figure shows the magnitude of the 0.7 ug/m3

 gap identified by 

South Coast air district modeling in relation to the progress we expect with the 

proposed State Strategy. The progress projected in PM2.5 levels from 2006 to 

2014 is largely the result of ARB’s existing mobile source control program plus 

the new measures in the proposed State Strategy. Emissions from mobile 

sources of NOx and SOx, the two key precursor pollutants of secondary PM2.5, 

are projected to drop by roughly 55 percent and 75 percent, respectively, 

between 2001 and 2014. Directly emitted particles from mobile sources are 

projected to drop 35 percent during this same time. 

A look at the South Coast air district’s emissions inventory shows that directly 

emitted PM2.5 from sources under district control are projected to increase – not 

decrease – by about 5 percent between now and 2014. Since the district’s 

modeling indicates that a ton of directly emitted particles has a greater impact on 

PM2.5 levels than a ton of NOx emissions, the District should explore additional 

measures to reduce emissions from these sources as a way to cut PM2.5 levels 

and close the 0.7 ug/m3 gap. 

South Coast PM2.5 Source Contributions 

Numerous source apportionment studies have been conducted in the South 

Coast reflecting snapshots of different sites and time. While the precise 

contribution varies, these studies have all identified diesel and gasoline vehicle 

exhaust, smoke from wood burning and cooking, and fugitive dust as important 

contributors to measured particulate matter concentrations. For this SIP, ARB 

staff conducted new source apportionment analysis (Positive Matrix 

Factorization) using monitoring data from 2003 through 2005 at Los Angeles and 

Riverside. This analysis, in conjunction with the results from past studies and 

assessment of the current emissions inventory, served as a screening tool to 

identify potential sources of primary PM2.5 that could provide opportunities for 

further control. 

ARB staff analyzed data from the LA-North Main and Rubidoux monitoring sites 

using the Positive Matrix Factorization (PMF) analysis method to identify the 

sources that contributed to PM2.5 captured on filters at those sites. The results 

of this analysis, illustrated in the pie charts below, indicate that sources of directly 

emitted particles are significant contributors to PM2.5 concentrations. Two key 

categories are smoke and airborne soil, which each contribute 6-10 percent to 

observed annual average concentrations in Los Angeles and Riverside. The 

smoke category reflects contributions from residential wood burning as well as 

managed and wildland fires; smoke from commercial cooking is also in this 

category. The airborne soil category reflects dust kicked up by vehicles traveling 

on paved and unpaved roads, and dust from construction and agricultural 

activities. 
April 26, 2007 77 

 

ARB staff solicited peer review of the recent source apportionment modeling, 

which concurred that the source contribution estimates were in the ballpark of 

expected values and suggested improvements for several technical aspects of 

the source apportionment modeling. Therefore, the body of evidence continues 

to suggest the significance of sources such as wood burning, cooking, and 

fugitive dust as opportunities for further targeted control efforts. 

Due to the significant population growth in the basin, emissions from residential 

wood burning, commercial cooking and fugitive dust will continue to increase. 

Stricter controls are needed to mitigate the emissions growth and provide 

emission reductions needed for PM2.5 attainment by the 2015 deadline. 

Measures for Residential Wood Burning 

ARB staff estimates that wood smoke contributes about 1.5 ug/m3

 to measured 

annual average PM2.5 levels at Rubidoux, based on staff’s PMF source 

attribution analysis. Wood smoke concentrations are higher during the winter 

months of November through February, when residential wood burning is the 

most likely source. The analysis also shows that wood smoke levels are higher 

on weekends and holidays, indicating that much of this residential wood burning 

s done for ambience and not for home heating purposes. Because the source 

attribution analysis suggested that residential wood burning was likely a 

significant part of PM2.5, ARB staff next used the South Coast air district’s air 

quality model to evaluate the potential for reductions. 

Residential wood burning rules are feasible. A number of air districts in the State 

have already adopted comprehensive residential wood burning programs, 

including the San Joaquin Valley and Great Basin Valley air districts. An 

important component of these residential wood burning programs is the 

mandatory curtailment of the use of fireplaces and woodstoves on days with 

expected high levels of particulate matter. These programs, particularly the San 

Joaquin Valley’s, demonstrate both their feasibility and their cost-effectiveness. 

Aug. 2003 - Dec. 2005 Average Source

Contribution in LA-North Main

Secondary 

nitrate

30%

Airborne 

soil

10%

Sea salt

9%

Gasoline 

vehicle

7%

Diesel

11%

Smoke

10%

Secondary 

Sulfate

23%

Aug. 2003 - Dec. 2005 Average Source 

Contribution in Rubidoux

Secondary 

nitrate

49%

Airborne 

soil

7%

Industrial

2%

Sea salt

11%

Gasoline 

vehicle

10%

Smoke

6%

Diesel

6%

Secondary 

Sulfate

9%
April 26, 2007 78 

Experience in the San Joaquin Valley has shown that public education about the 

health impact of wood smoke and the importance of curtailing wood burning is 

critical. Therefore, a phased approach in the South Coast has the best chance of 

success. For example, the program could begin as a voluntary program with an 

aggressive public education and information campaign. This could be followed 

by a mandatory program to restrict residential burning on selected days from 

November through February (with exemptions where no alternative heat source 

or natural gas service is available). Over the course of the program, analysis of 

measured air quality data would show its effectiveness and allow the district to 

optimize the program to get the needed reductions by 2014. 

ARB staff analyzed the impact of a full moratorium on residential wood burning 

from November through February using the South Coast district’s air quality 

model. The air quality modeling analysis showed that annual average PM2.5 

levels at Rubidoux would drop by 0.9 ug/m3 with a full moratorium between 

November and February. ARB staff also did a separate source attribution data 

analysis to assess the potential impact of a wood burning moratorium. The data 

analysis corroborated the modeling analysis. 

Although assuming a moratorium would be 100 percent effective is not realistic, 

the potential reductions from a complete moratorium are greater than needed to 

close the 0.7 ug/m3 gap. A residential wood burning program would only need to 

be 80 percent effective to fully close the 0.7 ug/m3 attainment gap (0.9 ug/m3 X 

0.80 = 0.72 ug/m3.) 

The South Coast air district is currently developing a residential wood burning 

program, but the staff’s most recent draft rule falls short of what is needed for 

PM2.5 attainment. The South Coast should include a comprehensive suite of 

requirements in the rule to both minimize the current level of burning, and to 

prevent further growth in this category. Feasible measures in rules adopted by 

other California air districts include a mandatory curtailment program, limits on 

the installation of wood burning devices in new homes and commercial facilities, 

and the required replacement of non-EPA compliant wood burning stoves. 

If measured air quality in 2014 indicates the need, a temporary moratorium in 

residential wood burning could be implemented. The South Coast’s modeling 

projects that the measures identified in ARB staff’s proposed State Strategy will 

reduce NOx emissions sufficiently to bring the Air Basin into attainment by about 

2017, indicating that the district would at some time have the option of lifting the 

most stringent elements of its localized controls for directly emitted PM2.5. 

Enhance Control of Smoke from Commercial Cooking 

As discussed previously, some of the smoke particles in the air come from 

restaurant cooking. By looking at the seasonal profile of the wood smoke levels 

as well as weekend versus weekday patterns, ARB staff estimated that cooking 

operations could comprise about one third of the wood combustion contribution 
April 26, 2007 79 

and therefore contribute approximately 0.5 ug/m3 to annual average PM2.5 at 

Rubidoux. 

The South Coast currently has a rule that applies to chain-driven charbroilers. 

However, a 1997South Coast survey found that only four percent of restaurant 

cooking operations operate chain-driven broilers, with the rest operating underfire broilers, griddles, or deep fat fryers. The Bay Area air district is in the 

process of developing a new rule that would require the installation of highefficiency filters on all types of cooking operations. 

Therefore, as a further means to reduce direct PM2.5 emissions, the South 

Coast air district could potentially strengthen its rule along the lines the Bay Area 

air district is exploring. This would require the installation of high-efficiency filters 

in both existing and new restaurants for under-fried broilers, griddles, and deep 

fat fryers, in addition to the existing provisions for chain-driven broilers. If a 

strengthened rule could get 20 percent reductions from these currently 

uncontrolled sources, it could reduce Rubidoux PM2.5 levels by another 

0.1 ug/m3. 

Strengthen Fugitive Dust Control 

Airborne soil is a third category of directly emitted PM2.5 that can provide an 

additional opportunity for further emission reductions. The estimated annual 

average contribution from airborne soil at Rubidoux is approximately 1.6 ug/m3. 

Sources of this soil include dust that is generated from travel on paved and 

unpaved roads, construction and agricultural activities, and dust that is kicked up 

by high winds. 

The South Coast has a comprehensive fugitive dust rule to reduce emissions 

from these activities. Required mitigation measures include application of water 

or other chemical stabilizers, paving and landscaping, minimization of dust trackout, and street-sweeping. However, the South Coast air district has adopted 

more focused dust controls for the Coachella Valley. Applying the focused 

Coachella Valley dust rules basin-wide may provide additional reductions. 

Likewise, increased fugitive dust enforcement activities or other targeted 

measures could be implemented to further reduce this source of PM2.5. 

Estimated Impact of Local Direct PM2.5 Measures 

These measures – residential wood burning, commercial cooking, and dust -- are 

reasonable, feasible, and cost-effective. The recommended temporary 

mandatory wood burning curtailment could be implemented with minor direct cost 

to the public. Other air districts have already adopted or are pursuing rules 

implementing these measures. Of course, given the magnitude of the South 

Coast PM2.5 challenge, the South Coast air district may need to do more. 
April 26, 2007 80 

Using both modeling and PMF analysis, ARB staff quantified potential benefits of 

the measures. The figure below illustrates how these measures could close the 

0.7 ug/m3 gap to reach attainment by 2015. 

0

5

10

15

20

25

30

35

1 2

Concentrations ug/m3

2014

0.7 ug/m3 gap

Progress from

ARB's

 Mobile Source 

Program

Up to 0.9 ug/m3

Residential 

Wood Burning

Up to 0.1 ug/m3 

Smoke Controls 

for Commercial 

Cooking

Additional Dust 

Controls

Filling the Gap

Standard
April 26, 2007 81 

Analysis of South Coast Air District Staff’s Proposed Additional Mobile 

Source Measures

As part of its draft plan, the South Coast AQMD has proposed several measures 

for reducing emissions from on-road and off-road mobile sources that the district 

staff believes will achieve 70+ additional tons per day of NOx reductions – the 

additional NOx reductions that the South Coast modeling indicates are needed to 

meet the PM2.5 standard. ARB staff have reviewed and assessed the proposed 

measures. 

 Summary Analysis of South Coast Proposed Mobile Source Measures 

(NOx emissions, summer planning average tpd) 

Measure 

AQMD 

proposed 

reductions

ARB Staff 

Assessment ARB Staff Comments 

ATPZEV 

Penetration 1 0 – 0.1 Penetration of 100,000 vehicles not practical by 2014. 

Light-Duty OnBoard Diagnostics 3 -- State law currently prohibits 

used car retrofit requirements. 

Heavy-Duty Trucks 21 0-12 Only feasible if subsidized. 

Funding not secured. 

Port Trucks 6 0-6 Only feasible if subsidized. 

Funding not secured. 

Construction 

Equipment 16 0-16 Only feasible if subsidized. Funding not secured. 

Cargo Handling 

Equipment 1 0-1 Less practical for industry than lease agreements with ports. 

Locomotives 16 -- Requires early U.S. EPA 

standards; ARB is preempted. 

Ground Support 

Equipment 1 0-0.2 

LAX settlement agreement 

covers 70% of GSE NOx 

emissions. 

Transport Refrigeration Units 1 -- Not technically feasible. 

Recreational Boats 1 0-1 Not practical on this scale. 

Funding not secured. 

Lower sulfur 

gasoline 5 -- Not necessary. Reductions already accounted for. 

Further reductions 

from diesel fuel 4 -- Not cost-effective. High total cost. 

Total 71 0-36 

About half of the tons are 

technically feasible, but only if 

subsidized at a cost in the 

billions of dollars. 
April 26, 2007 82 

The bulk of the additional NOx reductions from the South Coast staff’s proposed 

measures are from sources already identified for aggressive new controls in the 

State Strategy: heavy-duty trucks, port trucks, large off-road equipment, and 

locomotives. The State Strategy is estimated to achieve 322 tons per day of 

NOx reductions from already-adopted measures and 122 tons per day of NOx 

reductions from proposed new measures in the South Coast Air Basin by 2014. 

The State Strategy includes proposed measures to turn over and clean up the 

existing fleet of diesel vehicles and equipment at a scale that far exceeds 

anything attempted in the regulatory landscape to date. 

The South Coast air district staff’s proposal looks to reduce 71 additional tons per 

day of NOx through public funding assistance that would be used to increase the 

rate of turnover and clean up of the legacy fleet beyond that of the State 

Strategy. It estimates the public funding need at $600 million per year from 2009 

through 2014, for a total of $3 billion. 

ARB staff agrees with the South Coast air district staff’s assessment that the 

district’s suggested measures will cost billions of dollars, but ARB staff believes 

that only about 50 percent of the reductions, at most, are technically feasible 

even if subsidized. ARB staff believes that the turnover necessary to get 

reductions of this magnitude in this short time frame would not be possible. 

Furthermore, the funding for the scale of the measures envisioned by the South 

Coast air district staff is not currently available, so the measures cannot be 

included as approvable measures in the SIP. 

The following is a brief assessment of each of South Coast air district staff’s 

proposed measures: 

Accelerated Penetration of ATPZEVs (SCONRD-01)

Measure summary: 

This measure proposes that ARB use a combination of mandates and incentives 

to increase sales of advanced technology partial zero emission vehicles 

(ATPZEVs) that have an all-electric drive range (i.e. plug-in hybrid vehicles) to 

100,000 vehicles in the South Coast by 2014, and 1,000,000 vehicles by in the 

South Coast by 2020. The district estimated reductions of 1.0 tpd NOx and 

0.5 tpd VOC in 2014. The AQMD did not conduct a cost-effectiveness analysis. 

ARB staff assessment: 

Availability of an almost all-electric drive range ATPZEV is unrealistic based on 

available technology. Most optimistic projections indicate that 10,000 plug-in 

hybrids with a 10 mile drive range could be on the road in California by 2014 if 

three to four automobile manufacturers commit to producing them. The cost of 

plug-in hybrid vehicles could be approximately $2,000-5,000 more than hybrid 

vehicles on the market today. The uncertainty surrounding plug-in hybrids stems 

from the higher cost of larger batteries and commitment from automobile 

manufacturers to produce these vehicles. 
April 26, 2007 83 

Conversion of current ATPZEVs to plug-in hybrids is technologically possible, but 

not feasible on this scale under the South Coast proposed timeframe. 

Conversion packs used to enhance current hybrid technology have not been 

certified to meet safety or emission standards. 

OBD III for Light and Medium-Duty Vehicles (SCONRD-02)

Measure summary: 

This measure would require a higher level of on-board diagnostics (OBD III) on 

all new vehicles starting in 2012, and would require that existing 1996-2012 

vehicles be retrofitted with OBD III by 2020. It would achieve about 0.5 tpd NOx 

in 2014 at a total retrofit cost of $746 million, plus additional costs for new 

vehicles built in 2013 and later. 

ARB staff assessment: 

State law (Health & Safety Code section 43600) prohibits ARB from requiring the 

installation of control devices on used motor vehicles except when required or 

authorized by statute. Statutes enacted since have given ARB authority to 

require retrofit controls on heavy-duty vehicles. But no such statute has been 

enacted for light-duty vehicles, so ARB’s authority to mandate the installation of 

OBD retrofit kits on used light-duty vehicles is unclear. Consumer acceptance is 

also an issue. 

Further Emission Reductions from On-Road Heavy-Duty Vehicles (SCONRD-03)

Measure summary: 

This proposed measure calls for the reduction of 21 tons per day of NOx in 2014 

beyond the State Strategy’s proposed fleet modernization measure. The State 

Strategy’s proposed measure would achieve reductions equivalent to replacing 

30 percent of the heavy-duty fleet by 2014. The district’s proposal would retrofit 

or replace an additional pre-2010 or trucks at the rate of 15 percent per year 

above the proposed ARB program.. 

ARB staff assessment: 

To achieve the 21 tons per day of NOx reduction estimated, ARB staff estimated 

that more trucks would need to be replaced or retrofited in the 2011-2014 

timeframe than suggested in the district’s proposal, and that NOx retrofit 

efficiencies would need to be significantly higher than today’s technology. 

Currently, only one low-NOx catalyst device is verified for a 30 percent NOx 

reduction, and no devices are verified for on-road use that have a higher NOx 

removal efficiency. 

Using South Coast’s proposed strategy, ARB staff has estimated a 12 tons per 

day NOx reduction at an estimated cost of $812 million. This strategy could be 

implemented using available technology; however, it would add almost $1 billion 

to the cost of the very aggressive fleet modernization proposed by ARB. 
April 26, 2007 84 

Further Emission Reductions from Heavy-Duty Trucks providing Freight Drayage 

Services (SCONRD-04)

Measure summary: 

This proposed measure would retrofit and replace port trucks so that much of the 

port truck fleet would meet 2007-2010 standards by 2012, and the remainder 

would be equipped with PM and NOx retrofit devices. The district’s proposal 

would achieve approximately an additional 6 tons per day NOx reduction in 2014 

for an investment of over $1.8 billion. About half the replacement engines would 

use alternative fuels. 

ARB staff assessment: 

The technology for this proposed measure should be available; however, it is 

unknown how many alternative fuel engines will be certified to the 2007 and 2010 

standards. This measure is dependent on securing sufficient incentive funding 

and is only feasible if subsidized. 

Construction/Industrial Equipment Fleet Modernization (SCOFFRD-01) 

Measure summary: 

This measure proposes to reduce an additional 16 tons per day of NOx in 2014 

from large off-road equipment by achieving a 2018 fleet average in 2014 

(equivalent of ~Tier 3) with emission reductions equivalent to repowering all 

Tier 0 and Tier 1 equipment with Tier 3 or better engines (i.e., 2010 on-road 

engines). In 2020, the measure proposes to get reductions equivalent to 

repowering all Tier 2 equipment with Tier 4 or better engines and retrofitting all 

Tier 3 engines with selective catalytic reduction (SCR). 

ARB staff assessment: 

It is not technologically feasible to repower all Tier 0 and Tier 1 equipment with 

Tier 3 engines due to space constraints and other considerations. Repowers 

with Tier 4 engines will be even more challenging, if possible at all. Because of 

these technological constraints, a significant portion of the off-road equipment 

would have to be replaced to achieve the projected reductions. Equipment 

replacement is more expensive than repowering, and would substantially 

increase the cost of this measure and the magnitude of subsidies needed. 

This measure is feasible only if subsidized. The increased costs of replacing 

equipment makes the proposed measure much less feasible from a costeffectiveness standpoint. 

Further Reductions from Cargo Handling Equipment (SCOFFRD-02)

Measure summary: 

This measure would require the repowering of non-yard trucks (i.e., container 

cranes and loaders, front-end loaders, bulldozers, etc.) with Tier-4 offroad 

engines or the retrofitting of these engines with SCR. This measure is designed 
April 26, 2007 85 

to be phased in and to reduce NOx emissions from such equipment by 30%, and 

a total of 1 ton per day of NOx, by 2014. 

ARB staff assessment: 

The repowering of non-yard trucks with Tier-4 engines will be difficult due to the 

larger engine compartments required for these advanced emission control power 

systems in comparison to in-use engine compartments. As a result, many 

vehicles would probably be retrofitted with SCR systems in order to comply. 

While there are no technological barriers to SCR retrofits on these vehicles, the 

cost of these modifications will increase the capital investment requirements for 

terminal operators. Lease provisions requiring the same improvements will allow 

terminal operators to be eligible for subsidies from the Ports of Los Angeles and 

Long Beach. 

Further Reductions from Locomotives (SCOFFRD-03)

Measure summary: 

This measure recommends retrofitting remaining Tier 2 locomotive engines with 

DPF and SCR technology to achieve Tier 4 emission levels, which the district 

projects would reduce NOx emissions by an additional 11 tons per day of NOx in 

2014. 

ARB staff assessment: 

The State Strategy proposes an aggressive penetration rate to introduce Tier 4 

engines and retrofits for Tier 2 engines that depends on U.S. EPA adopting strict 

standards that go into effect before 2014. (U.S. EPA has proposed standards for 

new engines that go into effect by 2017; however, ARB staff continues to make 

the case that California needs earlier implementation.) The retrofit technology 

needed to bring locomotives up to Tier 4 standards has not been tested on 

locomotives as large as the long-haul locomotives used in the U.S. The 

availability of proven and tested technology at the scale envisioned is unsure. 

Since there is uncertainty about the introduction of the new standards prior to 

2014, staff believes that the 4 tons per day of NOx emission reductions from 

locomotives in the South Coast proposed in the State Strategy is the maximum 

commitment that should be made by the Board given the federal preemption. 

Emission Reductions from Airport Ground Support Equipment (SCOFFRD-04)

Measure summary: 

This measure proposes to reduce NOx emissions from ground support 

equipment by an additional 0.8 tons per day in 2014 through increased 

electrification and a lower fleet average. 

ARB staff assessment: 

A Stipulated Agreement settling litigation between the owners of Los Angeles 

International Airport (LAX) and neighboring cities over environmental impacts 

resulting from airport expansion requires LAX to implement a phased program to 

convert all ground support equipment to “extremely low emission technology 
April 26, 2007 86 

(such as electric power, fuel cells, or other future technological developments)” 

by 2015. This agreement will cover 70 percent of all ground support equipment 

in the air basin. If subsidized, this proposed measure could possibly achieve 0.2 

tons per day of NOx from the remaining ground support equipment at the other 

airports in the air basin. 

Further Emissions Reductions from Transport Refrigeration Units (SCOFFRD-05)

Measure summary: 

This measure proposes to retrofit in-use transport refrigeration units (TRUs) with 

SCR systems to reduce NOx emissions by 80 percent, reducing NOx by 1.1 

additional tons per day by 2014. 

ARB staff assessment: 

This measure has not been demonstrated to be technologically feasible due to 

the lack of SCR system testing on engines as small as those powering TRU 

systems. SCR is most effective when used in systems that can maintain a high, 

constant exhaust temperature to support the reaction that occurs on the 

catalyst’s surfaces. In general, SCR is not viable for engines of less than 150 

horsepower as they do not usually reach or maintain the needed exhaust 

temperatures. 

Accelerated Turnover and Catalyst Based Standards for Pleasure Craft 

(SCOFFRD-06)

Measure summary: 

This proposed measure calls for providing $52 million in incentives in 2014 for 

Southern Californians to purchase new recreational boats and jet skis sooner 

than they would have without the incentives. It is estimated to achieve 1 ton per 

day of additional NOx reductions in 2014. 

ARB staff assessment: 

While technically feasible if subsidized, it is not practical to assume that 50,000 

recreational boats and jet skis could be replaced in a very short period of time. 

No pilot projects have been conducted to test the feasibility and/or success of 

incentive-based replacement programs for pleasure craft. 

Further Emission Reductions from Gasoline Fuels (SCFUEL-01)

Measure summary: 

This measure calls for ARB to adopt a sulfur content limit of 10 ppm for future 

gasoline fuels, reducing NOx an estimated 5 tons per day by 2014. 

ARB staff assessment: 

This measure is not necessary. The South Coast air district analyzed the 

potential emissions reductions using the sulfur cap limits specified in the 

California reformulated gasoline (CaRFG) regulations. However, while the cap 

limit for sulfur is 30 parts per million by weight (ppmw), the average sulfur content 
April 26, 2007 87 

in gasoline marketed in California is 10ppmw. The emission benefits from this 

low sulfur gasoline have been used to allow other CaRFG limits to increase while 

minimizing costs and maximizing production. 

The Board is tentatively scheduled to consider amendments to the CaRFG 

regulation in June that would offset the increase in hydrocarbon evaporative 

permeation emissions resulting from the use of ethanol. The only practical path 

to offset this increase in hydrocarbon emissions is to use more ethanol, going 

from an average of 5.7% to 10% ethanol content. While this decreases 

hydrocarbon emissions, it increases emissions of NOx. , Refiners are expected 

to decrease sulfur levels even further to avoid this NOx increase, and as a result 

future CaRFG-compliant gasolines are expected to have an average of 5 to 

7ppmw sulfur. This is approximately the sulfur content that refiners would aim for 

to ensure continued compliance with a 10ppmw cap. This means that there are 

no emission benefits to be gained from adopting a 10ppmw sulfur limit. 

Further Emission Reductions from Diesel Fuels (SCFUEL-02)

Measure summary: 

This measure calls for ARB to adopt new regulations requiring the use of diesel 

fuel alternatives to replace 10 percent of conventional diesel fuel, reducing NOx 

emissions by an additional 4 tons per day by 2014. 

ARB staff assessment: 

South Coast staff expects the largest portion of the diesel fuel alternatives to be 

met through the use of gas to liquid (GTL) diesel, which has zero sulfur. They 

project that GTL diesel will cost 15 cents more per gallon than conventional 

diesel. ARB staff believes that the South Coast staff estimated cost for the GTL 

is low by a factor of 2 to 5. The cost to produce GTL is about $0.15 per gallon 

higer than the cost production cost of diesel, but this is based on the natural gas 

feedstock being virtually free. The cost of transporting the fuel to California, 

would add approximately another $0.15 per gallon. In addition, California would 

have to compete with the rest of the world to obtain GTL diesel, which means we 

would have to pay an “incentive cost” – we would have to pay more than other 

countries that also prize GTL for its ability to improve the overall quality of diesel. 

These factors make the proposed measure not feasible due to total cost and 

emission reduction cost-effectiveness. 
April 26, 2007 88 

How to Advance South Coast PM2.5 Attainment – Recommendations for 

Board Consideration

ARB staff has assessed the PM2.5 challenge in the South Coast starting with the 

premise that, as shown by South Coast air district modeling, additional measures 

are needed to reduce PM2.5 levels by 0.7 ug/m3

. ARB staff has concluded the 

following: 

• Given the PM2.5 progress measured over the last 15 years, and the new 

emission reductions that will occur, the South Coast may attain the 

standard by 2015 with the mobile source measures in the proposed State 

Strategy. Nevertheless, U.S. EPA requires the use of models in SIPs to 

demonstrate attainment; therefore, additional emission reductions should 

be identified. 

• The large new NOx and SOx reductions from mobile sources identified in 

the proposed State Strategy will provide the vast majority of the emission 

reductions that will occur by 2015. 

• Reversing the trend of rising PM2.5 emissions from sources under air 

district control through aggressive local measures to reduce directly 

emitted PM2.5 is critical to attainment. 

• Closing the 0.7 ug/m3 attainment gap by 2015 with additional NOx 

reductions is not realistic. The South Coast air district’s suggested mobile 

source measures are not feasible without billions of dollars of unsecured 

subsidies. 

• Feasible local air district measures for residential wood burning, 

commercial cooking, and dust exist to close the 0.7 ug/m3 gap and reach 

attainment by 2015.