## CHAPTER 5 FUTURE AIR QUALITY

Introduction Modeling Approach Future Air Quality Summary and Conclusions Basin Emissions Carrying Capacity (Emissions Budget) Projected Emission Trends Through 2010Chapter 5 Future Air Quality

5 - 1 

### INTRODUCTION
Air quality modeling is an integral part of th e planning process to achieve clean air. As mentioned in Chapter 1, the submittal of the 1997 Californ ia Ozone SIP served as the ozone attainment demonstration for the South Coast Air Basin and t hose portions of the Southeast Desert Modified Nonattainment Area which are under the District’s jurisdiction. The attainment demonstrations provided in this Plan reflect the updated emissions baseline estimates, new technica l information and enhanced air quality modeling techniques, and the control strategy provided in Chapter 4.
The Basin is currently desi gnated nonattainment for PM 10 , ozone, and carbon monoxide. Two of these pollutants - PM 10 , and ozone - are linked to common precursor emissions. The District’s goal is to develop an integrat ed control strategy which: 1) ensures that ambient air quality standards for all crite ria pollutants are met by the established deadlines in the federal Clean Air Act (CAA); and 2) achie ves an expeditious rate of reduction towards the state air quality standards. The overall control strategy is designed so that efforts to achieve th e standard for one criteria pollu tant do not cause unnecessary deterioration of another. A three-step mode ling process was originally crafted in the 1989 AQMP to develop the control strategy. The three-step process began with an analysis of future nitrogen dioxide air quality, followed by PM 10 air quality, and lastly, future ozone air quality. Subsequent attainment of the nitrogen dioxid e standard in 1995 reduced the number of st eps in the modeling process to two: analysis of future PM10 air quality followed by the future 1-hour ozone air quality. Air quality analyses under the 2003 AQMP are performed in keeping with this two-step modeling approach. However, future efforts to achieve the PM2.5 and 8-hour average ozone standards deserve consideration in the selection of the overall air quality standards.
The control strategy to meet federal and stat e carbon monoxide standards is independent of the PM10/ozone strategy. A photochemical grid model is used to project regional future carbon monoxide (CO) ai r quality. An additional “hot-s pot” analysis is required to assess impacts at intersections. Both analyses are performed in the 2003 AQMP to update the 1997 Revision of the Carbon Monoxide Attainment Demonstration (CO Plan). It is important to note that the Ba sin did not exceed the federal 8-hour average carbon monoxide standard in 2001 and exceed ed the standard only once in 2002. Thus, the Basin has met the criteria for attainme nt of the federal 8-hour average carbon monoxide standard. The 2003 CO Plan will serve as a replacement for the 1997 CO Plan that lapsed in 2000 and will provide the basis for a futu re maintenance plan for the Basin pending submi ssion of a petition for redesignation of attainment status.
Detailed information on the modeling approach , data gathering, m odel development and enhancement, model application, and interpre tation of results is pr esented in Appendix V. The following sections summarize the resu lts of the modeling efforts. Future ozone air quality projections for th e Coachella Valley are presen ted in Chapter 8 and in Appendix V.Final 2003 AQMP

5 - 2 

### MODELING APPROACH

PM10 Within the Basin, PM10 particle s are either directly emitted into the atmosphere (e.g., primary particles), or are formed through at mospheric chemical reactions from precursor gases (e.g., secondary particles). Primary PM10 includes road dust, diesel soot, combustion products, and other sources of fine particles. Secondary products, such as sulfates, nitrates, and complex carbon compou nds are formed from r eactions with oxides of sulfur, oxides of nitrogen, VOCs, and ammonia.

In the 1997 AQMP a combination of different mo deling techniques (receptor and photochemical grid models) were used to es timate the source contributions to ambient PM10 levels as measured at different monitoring sites. In addition, the air quality projections using the variou s modeling techniques were compared to a modified emissions rollback method (p erformed on a component-by-component basis) to provide assurance that the modeling techniques are givi ng directionally appropriate conclusions.

Of the modeling methodologies evaluated fo r the 1997 AQMP, a photochemical grid model application using the Ur ban Airshed Model with a fl exible chemistry mechanism (UAM-FCM) coupled with an em pirical linear chemistry module (LC) proved to be the most promising means to calculate annual av erage PM10 concentrations (excluding the secondary organic component). The UAM/LC methodology built upon the particle-incell (PIC) dispersion model appr oach used by the District si nce 1989 to examine annual primary particulates, ammonium, secondar y sulfate and nitrate concentrations. UAM/LC model performance was evaluated for 19 95 against speciated particulate data acquired from the PM10 Technical Enhancement Program (PTEP). (A detailed description of the PTEP monitoring program is provided in Appendix V of the 1997 AQMP. Receptor modeling us ing the Chemical Mass Balance (CMB) model with enhanced source profiles to estimate seconda ry organic particulate formation completed the model simulation package to estimate th e primary and secondary PM10 components.
A second methodology that coupled the UAM-FCM with a full gas phase and aerosol chemistry mechanism, the UA M-AERO model, was evalua ted for potential episodic PM10 prediction. While this methodology sh owed promise, the data resources required for the episodic model application were exte nsive for extended application. Since the 1997 AQMP, efforts have been made to m odify the UAM/LC to incorporate full gas phase chemistry with the empirical aerosol mechanism for long-ter m (LT) for annual applications. The resulting UAMAERO-LT was also extended to incorporate PM2.5 air quality prediction capability.
The newly developed UAMAERO -LT model is a simplified version of the UAM-AERO model. The detailed thermodynamic r outine (ISOROPIA) of the UAM-AERO model was replaced with the parameterized inorga nic gas/aerosol partiti oning module. The secondary organic aerosol formation scheme was replaced with a condensed version of the Carnegie Melon University secondary organic aerosol module. The CMU moduleChapter 5 Future Air Quality

5 - 3 treats organic products as semi-volatile speci es and employs an equ ilibrium approach to the gas/aerosol partitioning of these species. In addition, the detailed particle-sizing scheme used in the UAM-AERO model was also replaced by an observation-based, two size (fine and coarse) particle-sizing sche me for secondary ae rosols. UAMAERO-LT utilizes a full Carbon Bond IV gas-phase chemical mechanism and simulates the formation of particulate nitrate, sulfate, ammonium, organic carbon, elemental carbon and other primary particles.
For the 2003 AQMP, UAMAERO-LT model was used to simulate 1995 meteorological and air quality data to dete rmine Basin annual average PM 10 and PM 2.5 concentrations. Model performance was evaluated agai nst speciated particulate PTEP (PM 10 and PM 2.5 ) air quality data as well as Source Selective Inlet (SSI) High-Vol PM 10 data measured at the District’s ai r monitoring network from 1995. The future year attainment demonstration was analyzed fo r 2006, the target set by th e federal CAA. Additional PM2.5 model simulations are provided for 2010 to scope the potential reductions needed to meet the new fine particulate standards.

The UAMAERO-LT simulations incorporated several change s in model applications compared to the UAM/LC analyses. The vertical struct ure was increased to 5 layers (compared with the 2-layer analysis of UA M/LC). The temperature structure aloft was also modified to reflect a mo re comprehensive field of da ily, diurnal mixing heights. Finally, the simulations benefited from enhan cements made to the emissions inventory including updated ammonia emissions, impr oved specification of primary road and fugitive dust emissions and better allocation of those emissions through GIS land use mapping.

While UAMAERO-LT is the desired tool to simulate Basin annual average PM10 and PM2.5 concentrations, the model is not run w ith detailed, temperature-corrected dayspecific emissions. As a consequence, the annual model simulations are not suited for projecting maximum 24-hour average PM10 and PM2.5 concentrations. Speciated linear rollback is used to simulate peak 24-hour average concen trations at five key PTEP monitoring locations having detailed profiles of particulate components for the days when the 1995 Basin maximum conc entrations were observed.

The following section summarizes the PM 10 modeling approach conducted in preparation for this Plan. Details of the PM10 modeling are presented in Appendix V.

AQMP Modeling Approach
The 2003 AQMP annual average PM 10 modeling employs a deterministic approach to demonstrate attainment of the PM 10 in 2006. UAMAERO-LT simulations were conducted for the 1995 base year meteor ology and emissions to determine model performance when compared to the speciated ambient PM 10 and PM2.5 monitoring data. Performance comparisons were conduct ed for the ammonium, nitrates, sulfates,Final 2003 AQMP

5 - 4 secondary organic matter, elemental carbon, pr imary and total particulate mass for five PTEP monitoring sites (Los Angeles, Anah eim, Diamond Bar, Rubidoux, and Fontana). Additional performance comparisons are conduc ted for the SSI particulate mass at 19 District sites that routinely measured SSI Hi-Vol data to demonstrate the representativeness of the modeling simu lation throughout the modeling domain.

UAMAERO-LT is used in combination with emissions projections to determine PM 10 air quality for the 2006 futu re-year baseline and controlled scenario. A weight of evidence demonstration is pr ovided in Appendix V to address future year PM10 predictions at "hot spot" grids, where the particul ate emissions have significant uncertainty. A supplemental PM2.5 simulation is provided for the 2010 future-year control scenario to quantify the extent of additional emissions reduction needed to meet the PM2.5 beyond that date. The results of the 2010 PM2.5 concentrations are presented in Chapter 10.
All future-year PM10 air quality projections are compared to the 1995 concentrations. The 1995 Basin maximu m annual average PM 10 concentration was equivalent to the 1995 design value (69 μg/m 3 for 1993-1995). Th e 2001 PM10 desi gn value for the South Coast Air Basin is approximately 6 perc ent lower than that of 1995 at 65 μg/m 3 (averaged for 1999-2001).
Linear rollback on particulate component spec ies is used to assess future year 24-hour maximum PM10 concentrations at the five PTEP monitoring sites. Observed 24-hour average maximum PM10 for 1995 ar e used to anchor the rollb ack calculation for future year impacts. For Rubidoux, the 1995 second maximum PM 10 concentration (206 μg/m3) observed in 1995 is us ed for the analysis since th e peak 24-hour average (219 μg/m3) occurred during a “Santa Ana” high wind day. The peak concentration, (April 9, 1995), has not been tagged as a natural event in the AIRS data set since the policy did not take effect until 1997. It is useful to note that the 24-hour PM 10 standard has been exceeded on only 16 days since 1995 with 10 of those days being high wind events. In addition, since 1997, onl y high wind events have caused the 24-hour standard to be exceeded.
Projected controlled emissions for 2006 and 2010 are used to determine future 24-hour maximum PM10 at the five key monitoring sta tions. Detailed discussions of all model results are provided in Appendix V.



### Ozone
The CAA requires that ozone nonattain ment areas designated as serious and above use a photochemical grid model to demonstrate attainment. In the 1997 AQMP, UAM, the photochemical model at that time recommende d by the U.S. EPA guidance (40 CFR Part 51, Appendix W), was used with the CB-IV chemistry package for the Basin ozone attainment demonstration and supporting an alyses. UAM is an urban scale, threedimensional, grid-type, numerical simulation model. It is designed for computing ozoneChapter 5 Future Air Quality

5 - 5 concentrations under short-term , episodic conditions lasting on e to three days. On April 15, 2003, the final revisions to Appendix W were publishe d in the Federal Register. Revised Appendix W removed UAM as the sole recommended model by EPA for ozone analysis, and in its place did not name a su ccessor. Revised A ppendix W promotes the use of models employing state-of-the -art advances in science.
For the 2003 AQMP, UAM with the Carbon Bond IV (CB -IV) chemistry is used to demonstrate future year (2010) attainment of the 1-hour federal ozone standard. Experience gained in implementing UAM and interpreting the imp acts of the simulation results in prior AQMPs prov ides the current applicati on with a large measure of confidence. This is demons trated both in the model’s ab ility to simulate peak ozone concentrations for a new historical meteorol ogical episode (discussed later) and in the capacity of the model to es timate observed Basin maximum ozone concentrations for 2002, as a "mid-course" evaluation. Perf ormance statistics and model inputs are discussed extensively in Appendix V.
Regardless, while UAM has been selected as the primary modeling tool for the 2003 AQMP, the California Photochemical Grid Model (CALGRID) [Yamartino, et. Al, 1989) using SAPRC99 chemistry was also eval uated for its potential to simulate base and future year ozone to demonstrate Basin a ttainment of the federal one hour standard. CALGRID is a regional scale, three dimensi onal, grid type model that embodies several enhancements in layer structure, advection and dispersion schemes not found in UAM. CALGRID has been used for se lected ozone attainment de monstrations nationwide and has been used in ozone analys es in other countries. The SAPRC99 chemistry reflects the state of the science in chemical mechanisms with its enhanced treatment of reactivity and interaction of additional ch emical species. An expert panel of air quality researchers was convened to review the 2003 AQMP modeling efforts. Their general recommendation supported the transition to th e CALGRID/SAPRC99 modeling system.

A discussion of the CALGRID/SAPRC99 m odeling system and its performance is provided as attachment A-7 to Appendix V. In general, model performance for error and bias is good, however, the model was unab le to simulate peak base year ozone concentrations (approximately 12 percent lower than observatio ns) using the same emissions as the UAM. It wa s assumed that the tendency to under predict in the base year would carry through to future year si mulations and result in the underestimation of emission reductions needed to meet th e federal standard. (The CALGRID 2010 simulations are presented as part of a techni cal report in Attachment -7 of Appendix V. When the CALGRID projected 2010 ozone concentrations for the two control options are scaled for under prediction in the base year, the adjusted predicted ozone carrying capacity is essentially equivale nt to the UAM ozone projections. As a consequence, the carrying capacity would not change).
Like CALGRID/SAPRC99, the Comprehensiv e Air Quality Model with Extensions (CAMx) [Environ, 2002 ], with SAPRC99 chemistry, wa s also evaluated as a possible modeling tool for the AQMP attainment dem onstration; however it also was unable toFinal 2003 AQMP

5 - 6 simulate base year peak ozone concentratio ns. (CAMx with CB-IV chemistry is being run in a low reactivity mode to support of the carb on monoxide attainment demonstration to take advantage of its la yer structure meteorological and dispersion advection schemes). As a consequence, UAM was used for the 2003 AQMP regional ozone simulations. However, based on the expert review panel recommendations, the District is committed toward using the CALGRID/SAPRC99 mode ling system in the future.
It is desirable to perform ozone air quality analyses using several different meteorological episodes. Only one episode was modeled for the 1989 AQMP. For the 1991 AQMP, three ozone meteorological ep isodes were used to predict future air quality; two meteorological episodes during the 1987 Southern California Air Quality Study (SCAQS) (Lawson, 1990) were used to complement the single episode from the 1989 AQMP. For the 1994 AQMP, two additional SCAQS episodes were added to the analysis and for the 1997 AQMP, the first modeling epis ode developed for the 1989 AQMP (the June 5-7, 1985 episode) wa s removed from further use since such meteorological conditions rarely occur in the Basin.

The Southern California Ozone Study (SCOS97) [Jackson, et.al., 1998, Doislager, 1998, among others] measured ozone, precursor an d meteorological data for several episode periods during the summer and fall of 1997 . The monitoring program took place approximately one and a half years after th e implementation of Ca lifornia Phase-II fuel reformulation. The goal of SCOS97 was to provide comprehensive air quality and meteorological data for the purpose of evalua ting state of the art meteorological and air quality models for use in attainment demons trations. While intens ive field monitoring during SCOS97 captured several ozone mete orological episodes including a weekend episode, the period beginning August 3-7, 1997 produced the Basin second maximum concentration (0.188 ppm). This meteorol ogical episode has been selected for the current attainment demonstration. One ad ditional candidate episode was considered for the attainment demonstration, (July 16, 1998), however, when evaluated using statistical ranking, the July 1998 episode, like the June 1985 episode, wa s determined to be rare event ranked at the 99.9 th percentile of the episode di stribution with an expected frequency of less than once four years.
The current form of the federal ozone air quality standard allows for the standard to be exceeded once per year to account for these rare meteorological events. As such, a peak ozone concentration due to meteorological conditions in the June 1985 or July 1998 episodes would not be accounted for in the current form of the standard. In addition, EPA modeling guidelines recomme nd that meteorological epis odes used for attainment demonstration is no older than ten years. The August 1997 SCOS 97 episode satisfies these criteria.
Table 5-1 lists the primary meteorological episode (Augus t 1997) used for ozone air quality analysis including the peak measured ozone concentr ations in the South Coast Air Basin, the Mojave Desert Air Basin a nd the Coachella Valley portion of the SaltonChapter 5 Future Air Quality

5 - 7 Sea Air Basin. One additional SCAQS epis ode (August 1987) is carried forward from the 1997 AQMP to provide continuity betw een AQMP attainment demonstrations. The August 1997 episode is comprised of "Typ e-1" high potential, meteorological days categorized by the classification system us ed in previous atta inment demonstration (Appendix V-P, 1989 AQMP). While it is desirable to have meteorological episodes from several categories, the "Type-1" meteor ology has accounted for 52 percent of all days exceeding the federal 1-hour standa rd, averaged from 19 96-2002. With the continuing trend of reduced precursor emissi ons it is expected that the percentage of days exceeding the standard ha ving "Type-1" meteorology w ill increase and eventually become the sole path to high ozone concen trations in the Basin. Nonetheless, UAM future air quality projections are included for the August 1987 SCAQS episode that features days in meteorological categories other than "Type-1."

TABLE 5-1 Ozone Meteorological Episodes Used fo r the Ozone Attainment Demonstration

Peak Concentration Peak (pphm) Episode South Coast Mojave Desert Salton Sea. - Coachella Valley Introduced in the

August 26-28, 1987 29 13 16 1991 AQMP August 3-7, 1997 19 14 16 2003 AQMP

The baseline performance evalua tion of the 1987 meteorological episode is provided in the 1994 AQMP. A comp rehensive description of the UAM modeling system including, air quality and meteorological i nputs and the performan ce evaluation using the 1997 August SCOS episode for the base and future year simulations is provided in Appendix V.



### Carbon Monoxide
The CAA requires the use of an area wide model to describe the accumulation of emissions over several hours and kilometers within the region. CAMx, a fixed layer, regional simulation model, is used for th e area wide analysis. CAL3QHC, a roadway intersection model, is used to calculate carbon monoxide concentrations near the intersection. CAMx and CAL3QHC were both simulated for a new meteorological modeling episode, October 31-November 1, 1997, during the SCOS97 monitoring program. The SCOS97 episode replaces th e December 1989 episode and ranks second in observed peak carbon monoxi de concentrations (17.0 ppm 8- hour average) in the post Phase II fuel reformulation period (1996 - 2002).

Previous carbon monoxide attainment demonstr ations were submitted to the U.S. EPA in 1992, 1994 and 1997 to bring the Basin into attainment with the federal standard in 2000. In 2000, the CO standa rd was exceeded in the Basin on thr ee days, leaving theFinal 2003 AQMP

5 - 8 Basin in non-attainment status. At that ti me, a request to EPA for an extension of the attainment date to 2002 was planned to be in cluded in the 2000 revision to the AQMP. However delays in the ava ilability of newer on-road m obile emissions estimates (EMFAC2002) forced a post ponement of the plan submittal until 2003. As a consequence, the carbon monoxide attainme nt demonstration pr ovided in the 1997 AQMP has lapsed.

To meet this void, the 2003 AQMP contains a revised CO Plan that jointly uses ambient monitoring data and modeling results for 2002 and emissions projections for future years to provide a weight of eviden ce demonstration that will replac e the prior submittals. The CAMx and CAL3QHC modeling results are used to demonstrate the progress made towards attaining the federal 8-hour air quality standard for carbon m onoxide in the year 2002. The 2002 observed car bon monoxide concentrati ons, coupled with the 2002 modeled air quality and the EMFAC2002 pr ojected seven percent annual carbon monoxide emissions reductions for the Ba sin serve as a weight of evidence demonstration of compliance to the federal standard. A complete description of the modeling analysis is presented in Appendix V.


### Visibility
Future-year visibility in the Basin is projected using the results derived from a regression analysis of visibility with ai r quality measurements. The regr ession data set consisted of aerosol composition data collected during a special monitoring program conducted concurrently with visibility data collection (prevailing vi sibility observations from airports and visibility measurements fr om District monitoring stations). A full description of the visibility analysis is given in Tech nical Report V-C of the 1994 AQMP.


### FUTURE AIR QUALITY

PM10

Under the federal Clean Air Act, the Ba sin must comply with the federal PM 10 air quality standards by December 31, 2001 [S ection 188(c)(2)]. A five-year extension could be granted if attainment cannot be demonstrated a nd several other conditions are satisfied [Section 188(e)]. As indicated in Chapter 1, the Di strict has formally requested U.S. EPA to grant the five-y ear extension. Figure 5-1 depicts future annual average PM10 air quality projections at five PM10 monitoring sites ha ving comprehensive particulate species characterization comp ared to federal and state annual PM10 standards, respectively. Show n in the figure are the estima ted baseline conditions for the years 1995, 2006 and 2010, al ong with projections for 20 06, and 2010 with control measures in place. All sites will attain the federal annual standard by the year 2006. None of the sites will meet the recently revised state annual PM10 standard (20 μg/m 3 based on a geometric av erage) by 2010.Chapter 5 Future Air Quality

5 - 9 The projections for the 24-hour state and federal standards are shown in Figure 5-2. The results are similar to those for the annual standa rds. All areas will be in attainment of the federal 24-hour standard (150 μg/m 3 ) by 2006. With respec t to the state 24-hour standard (50 μg/m 3 ), none of the sites will be in attainment by 2010.



### Ozone
As an nonattainment area designated as extrem e, the Basin must comp ly with the federal ozone air quality standard by November 15, 2 010. The attainment demonstration shown here addresses this requirement. As disc ussed earlier, two meteorological episodes August 3-7, 1997 and Augus t 26-28, 1987 are used in the ozone attainment demonstration. The ozone modeli ng discussion that follows is divided into two sections: projected baseline concentrati ons and predicted controlled concentrations. The baseline projections assume no further controls in the future years and the predicted controlled concentrations assume the implementation of the 2003 AQMP cont rol strategy at the appropriate level for the year modeled.



### 0 50 100

Central LA Anaheim Diamond Bar Fontana RubidouxConcentration (ug/m3)

1995-Baseline 2006-Baseline 2006-Controlled 2010-Baseline 2010-Controlled Option-1

FIGURE 5-1 Annual Arithmetic Average PM10 Concentrations Federal Standard 50 μg/m 3Final 2003 AQMP

5 - 10 0 150 300

Central LA Anaheim Diamond Bar Fontana RubidouxConcentration (ug/m3)

1995-Baseline 2006-Controlled 2010-Controlled

FIGURE 5-2
Maximum 24-Hour PM 10 Concentrations

Table 5-2 shows the total VOC and NO x emissions in the Basi n and projected maximum 1-hour average ozone concentrations for August 5 th and 6 th , the most restrictive days of the 1997 episode and August 27 th and 28 th , the most restrictive days of the 1987 episode. The emissions presented in Table 5-2 are ep isode-specific and therefore differ from the planning inventories reported in Chapter 3. Baseline emis sions and the predicted Basin maximum ozone concentrations are presen ted for 2002, 2007 and 2010. The 2002 baseline ozone simulation provides a "mid-c ourse" evaluation of model performance. The predicted 1-hour maximum concentrati ons simulated for the two meteorological episodes compare well with th e 2002 annual basin maximu m concentration (169 ppb) that was observed on a day having statistical ly similar meteorological conditions to the August 5, 1997 episode.
Baseline predictions for 2007 serve a dual capacity: The 20 07 simulation is required to assess transport to the Mojave Desert Air Ba sin and is directly used in the Coachella Valley portion of the Salton Sea Air Basin ozone attainment demonstration. (The Coachella Valley Plan and oz one attainment demonstration is discussed further in Chapter 8. Impacts to the Mojave Desert Air Basin are discussed in Appendix V). In addition, the 2007 simulation serves and a second "mid-course" evaluation of the modeling in response to expected reductions in VOC and NOx. Federal Standard 150 μg/m 3Chapter 5 Future Air Quality

5 - 11 TABLE 5-2
Basin Precursor Emissions and UAM- Predicted Ozone Concentrations

Peak Ozone concentration (ppb) Peak Ozone concentration (ppb) Precursor Emissions (Tons Per Day)

Aug 5 th Aug 6 th Aug 27 th Aug 28 th Year/Scenario

VOC NO x 1997 1997 1987 1987
1997 Historical Year 1262 1283 199 193 143 173 2002 Baseline 919 1075 162* 168* 127* 153* 2007 Baseline 710 892 146 153 116 139 2010 Baseline 671 764 153 148 120 136

* Predicted peak ozone concentrations for August 5th, 1997 and August 28 th, 1987 meteorological episodes for 2002 baseline emissions are provided as "mid-course" estimations of model performance The modeled concentrations are compared to an observed 2002 Basin maximum ozone concentration of 169 ppb which occurred under similar meteorological conditions. Figure 5-3 depicts the predicted baseline basinwide maximum ozone without further AQMP measures for the two meteorological ep isodes modeled. As shown, basinwide peak ozone concentrations are on the or der of 140 - 150 ppb from 2002 to 2010, regardless of the meteorological episode simulated.



### 0 50 100 150 200 250

1997 2002 2007 2010Concentration (ppb)



### Aug. 5, 1997 Aug. 6, 1997 A u g . 27,1987 A u g . 28, 1987

FIGURE 5-3
Baseline Basinwide 1-Hour Maximum Ozone Concentrations Federal Standard (124 ppb)Final 2003 AQMP

5 - 12 Control Strategy Impacts
Two options for controlled emissions are pr esented in Table 5-3 reflecting differing penetrations of NOx and VOC controls by the year 2010. Option-1 presents the District's proposed control strategy needed to attain the federal 1-hour standard. Option1 holds NOx emissions held at the 1997/99 SIP levels. This low NOx plan is designed to ensure progress towards lowering Basin PM2.5 concentrations.
A secondary backstop control st rategy that demonstrates atta inment using the same air quality model, atmospheric chemistry, and ep isodes, but utilizes a different mix of VOC and NOx reductions was also simulated. This strategy assumes no additional NOx or VOC emission reduction measures from sources under federal jurisdiction. Under this scenario, the NOx emissions target would be adjusted to cover the loss of federal reductions, while the VOC target would stay the same for oz one attainment in 2010. The effect of using the primar y (Option-1) and backstop (Opt ion-2) control strategies on the mix of VOC and NOx reductions that resu lt in attainment are shown in Table 5-3.
Figure 5-4 shows the predicted Basin-wide maximum ozone for the two meteorological episodes for 2010, with the tw o proposed emission control strategies in place. The results indicate that both proposed control strategies will bring the entire Basin into compliance with the federal ozone standard by the year 2010. Regional maximum ozone concentrations in the year 2010 will be between 98 and 124 ppb.
Figure 5-5 shows the predicted Basin-wide 8-hour average maximum ozone for the two meteorological episodes for 2010, with the two proposed emission control strategies in place. The results indicate that neither bot h proposed control strategies will bring the entire Basin into compliance with the federal oz one standard (80 ppb) by the year 2010. The impact of the two strategies is discussed further in Chapter 10.

TABLE 5-3

Precursor Emissions and Model-Pr edicted Ozone Concentrations

Peak Ozone concentration (ppb) Peak Ozone concentration (ppb) Precursor* Emissions (Tons Per Day)

Aug 5 th Aug 6 th Aug 27 th Aug 28 th Scenario

VOC NO x 1997 1997 1987 1987

Controlled Emissions: Option-1 313 541 123 120 98 111

Controlled Emissions Option-2 314 619 123 124 98 112

* Day specific emissions for August 5, 1997Chapter 5 Future Air Quality

5 - 13 The spatial distribution of maximum ozone con centrations for the 1997 historical year is shown in Figure 5-6. Futu re year ozone air quality pr ojections for 2010 with and without implementation of all control measures are presented in Figures 5-7 through 5-9. Figure 5-8 depicts the spatial distributi on of maximum predicted ozone for control scenario Option-1 while Option-2 is presen ted in Figure 5-9. The predicted ozone concentration will be significantly reduced in the future years in all parts of the Basin, the Mojave Desert Air Basin, and the Salt on Sea Air Basin with the implementation of proposed control measures in the South Coast Air Basin.



### 0 20 40 60 80 100 120 140

Option-1 Option-2Concentration (ppb)



### Aug. 5, 1997 Aug. 6, 1997 Aug. 27, 1987 Aug. 28, 1987

FIGURE 5-4 2010 Basinwide Maximum 1-Hour Average Ozone Concentrations: District Proposed Emissions C ontrol Scenario: Option-1, and Backstop Emissions Control Scenario: Option-2 Federal Standard (125 ppb)Final 2003 AQMP

5 - 14 

### 0 20 40 60 80 100 120

Option-1 Option-2Concentration (ppb)



### Aug. 5, 1997 Aug. 6, 1997 Aug. 27, 1987 Aug. 28, 1987

FIGURE 5-5 2010 Basinwide Maximum 8-Hour Average Ozone Concentration: District Proposed Emissions Cont rol Scenario: Option-1, and Backstop Emissions Control Scenario: Option-2 Federal Standard Federal Standard (85 ppb)Chapter 5 Future Air Quality

5 - 15 FIGURE 5-6 Model-Predicted Maximum Hourly Ozone Concentrations in 1997Final 2003 AQMP

5 - 16 FIGURE 5-7 Model-Predicted Maximum Hourly Ozone Concentrations in 2010 (with rules adopted as of September 2002)Chapter 5 Future Air Quality

5 - 17 FIGURE 5-8 Model-Predicted Maximum Hourly Ozone Conc entrations in 2010: Control Option-1Final 2003 AQMP

5 - 18 FIGURE 5-9 Model-Predicted Maximum Hourly Ozone C oncentrations in 20 10: Control Option-2



### Carbon Monoxide

As discussed earlier, based on carbon monoxi de air quality monitoring conducted during 2001 and 2002, the South Co ast Air Basin has technically met the federal carbon monoxide criteria for attainment. The pr edicted 2002 maximum 8-hour average CO concentrations coupled with the projected trend of reduced on-road carbon monoxide emissions serve as a replaceme nt for 1997 CO Plan and pr ovides the basis for a CO maintenance plan.

The carbon monoxide air quality projecti ons are based on CA Mx and CAL3QHC simulations analysis for the fall meteorologic al episode. The Oc tober 31-November 1, 1997 episode recorded maximum 1-hour and 8-hour average carbon monoxide concentrations of 19.0 ppm and 17.0 ppm, respectively. Thes e were the highest recorded values in the Basin since 19 96. Table 5-4 summarizes th e carbon monoxide emissionsChapter 5 Future Air Quality

5 - 19 and predicted concentrations for 1997 and 2002. (All c ontrol measures implemented through October, 2002 are included in the baseline emissions). The 2002 predicted 8- hour average maximum concentration clos ely matches the maximum observed carbon monoxide concentration measured at Ly nwood in 2002 (10.1 ppm on January 8 th ). However, the concentration exceeds the federa l and state levels by a marginal amount.

Figure 5-10 depicts the trend of EMFAC200 2 projected carbon monoxide emissions for 1997 through 2005. On-roa d CO emissions from vehicles that are the primary contributors to urban carbon monoxide episode s are projected to decrease by an average of seven percent per year in 2003 through 2006. Total CO emissions reductions for all categories are projected to be reduced approxi mately 6 percent per year through 2006. Using liner rollback, the base on the projecte d reduction in CO emissions, the predicted carbon monoxide maximum 8-hour concentration is expected to be reduced to below the federal standard of 9.4 ppm in 2003 and be low the California standard of 9.0 ppm in 2004. The continued reductions in carbon mo noxide emissions are expected to maintain the attainment of the federal 8-hour standa rd demonstrated throug h observations in 2001 and 2002.

TABLE 5-4
Carbon Monoxide Emissi ons and Model-Predic ted Concentrations
Year/Scenario CO-Planning Inventory (tons/day) 8-hr Maximum Concentration (ppm) 1-hr Maximum Concentration (ppm)
1997 Baseline 6460 14.9 16.7

2002 Baseline 4835 9.9 10.8

2003 Predicted 4527 9.1 9.9

2004 Predicted 4278 8.4 9.2
2005 Predicted 4029 7.8 8.5

State 1-hr CO standard = 20 ppm State 8-hr CO standard = 9.0 ppm Federal 8-hr CO standard = 9.5 ppmFinal 2003 AQMP

5 - 20 0 1000 2000 3000 4000 5000 6000

1997 1998 1999 2000 2001 2002 2003 2004 2005(TPD)

FIGURE 5-10 EMFAC2002 Projected On-Road Carbon Mono xide Emissions for 1997 Through 2005



### Visibility
The results of the visibility an alysis for Rubidoux are illustra ted in Figure 5-11. Without the proposed AQMP control measures, annual average visibility is projected to improve at Rubidoux to approximately 7.9 miles in the year 2010.

With the implementation of all proposed emi ssion controls for 2010, the annual average visibility would improve to over 9 miles at Rubidoux



### SUMMARY AND CONCLUSIONS
Figure 5-12 shows the model-predicted regi onal peak concentrations for the three nonattainment criteria pollutants, as percenta ges of the most stringent federal standard, for the years 2002, 2006 , and 2010, (with and without fu rther emission controls). Figure 5-13 shows similar information related to th e most stringent California state standards.Chapter 5 Future Air Quality

5 - 21 FIGURE 5-11 Annual Average Daytime Visibili ty Projections at Rubidoux



### 0 100 200

PM10 (An. Avg.) Ozone (1-Hour) COPercent of Standard

Historic Base 2002 Baseline 2003 Baseline 2006 Baseline 2006 Control 2010 Baseline 2010 Option-1/Option-2

FIGURE 5-12 Projection of Future Air Quality in the Basin in Comparison with the Most Stringent Federal Standards 

### 0 2 4 6 8 10

1986 2006 2010Visibility (Miles)



### Baseline ControlFinal 2003 AQMP

5 - 22 0 100 200 300 400

PM10 (An. Avg.) Ozone (1-Hour) COPercent of Standard

Historic Base 2002 Baseline 2003 Baseline 2006 Baseline 2006 Control 2010 Baseline 2010 O p tion-1/O p tion-2

FIGURE 5-13 Projection of Future Air Quality in the Basin in Comparison with Most Stringent California State Standards
Table 5-5 summarizes the expected year for a ttainment of the various federal and state standards for the four polluta nts analyzed. As shown, th e Basin will be in compliance with federal and state standards for all pollutants except the state ozone and PM 10 standards by the year 2010.Chapter 5 Future Air Quality

5 - 23 TABLE 5-5 Expected Year of Complian ce with State and Federal Standards for the Four Criteria Pollutants

Concentration Expected Pollutant Standard Level Compliance Year Ozone NAAQS 1-hour 125 ppb 2010 CAAQS 1-hour 90 ppb beyond 2010

PM 10 NAAQS Annual 50 ug/m 3 2006 NAAQS 24-hour 150 ug/m 3 2000 CAAQS Annual 20 ug/m 3 beyond 2010 CAAQS 24-hour 50 ug/m 3 beyond 2010

CO NAAQS 8-hour 9 ppm Achieved * NAAQS 1-hour 35 ppm Achieved * CAAQS 8-hour 9 ppm 2004 CAAQS 1-hour 20 ppm Achieved

* The Basin has been achieving the federal 1- hour CO air quality standard since 1990. In 2002, the Basin achieved the 8-hour CO air quality standard. The Basin is still considered nonattainment until a petition for rede signation is submitted by the state and is approved by EPA.



### BASIN EMISSIONS CARRYING CAPACITY (EMISSIONS BUDGET)
The District is required to separately iden tify the emission reductions and corresponding type and degree of implementation measures required to meet federal and state ambient air quality standards. Secti on 40463(b) of the California St ate Health and Safety Code specifies that, with the active participation of the Southern California Association of Governments, a South Coast Air Basin emi ssion carrying capacity for each state and federal ambient air quality standard shall be established by the South Coast District Board for each formal review of the Plan and shall be upda ted to reflect new data and modeling results.
A carrying capacity is defined as the maxi mum level of emissions that enable the attainment and maintenance of an ambient air quality standa rd for a pollutant. Emission carrying capacity for state standards shall not be a part of the State Implementation Plan requirements of the Clean Air Act for the South Coast Air Basin.Final 2003 AQMP

5 - 24 Emission carrying capacity as defined in th e Health and Safety Code is an overly simplistic measure of the Basinwide allowabl e emission levels for specific ambient air quality standards. It is high ly dependent on th e spatial and temporal pattern of the emissions. Because of the multi-component nature of PM 10 , carrying capacity for the contributing emittants can vary signif icantly. For ozone and secondary PM 10 components, the carrying capacity is a non-linear function among their precursors.
The federal Clean Air Act require s that plans contain an emissi ons budget that represents the remaining emissions levels that achieve the applicable attainment deadline. Based on the modeling results, a set of carrying capacities can be defi ned corresponding to federal and state ambient air quality standa rds for carbon monoxide, PM10, and ozone. VOC and oxides of nitrogen are used for ozone. PM 10 additionally requires reductions of sulfur oxides and directly emitted PM10

. Carbon monoxide is based solely on carbon monoxide emissions. Table 5-6 shows the emissions carry ing capacities for the Basin to meet federal air quality standards. Thes e estimates are based on emission patterns estimated for each of the federal attainment years (i.e., 2003 for carbon monoxide, 2006 for PM 10 , and 2010 for ozone Option-1 and Option-2).
Comments were raised during th e public review period for th e plan regarding the various combinations of carrying cap acity for the ozone attainment demonstration. More specifically the question posed was what ma ximum NOx loading and its corresponding VOC level as a carrying capac ity could the Basin tolerate while (1) attaining the ozone standard in 2010 and (2) attaining the PM 10 standard in 2006 and maintaining that standard in 2010. Staff cond ucted a series of ozone and pa rticulate matter simulations to generate isopleths of predic ted concentration as a functi on of NOx and VOC emissions to attempt to answer th e question. The results of the an alysis indicate that the carrying capacity provided in Control Option-2 repres ents the approximate upper bound for NOx emissions to achieve the ozone standard.



### PROJECTED EMISSION TRENDS THROUGH 2010
Figures 5-14 through 5-17 sh ow the projected emission trends for both NOx and VOC through the year 2010. Depicted are scenar ios for the baseline ca ses (e.g., no further rules), and for the contro lled cases (with the Option- 1 2003 AQMP Measures). Categories are described slightly different than most emission inventory summaries in that permitted sources (e.g., those emis sion sources which are permitted with the District) are specifically delineat ed. These figures show that emission levels continue to decrease through the year 2010, especially fo r the controlled case, when attainment with the federal ozone standard is expected. Fo r VOCs, emissions are initially dominated by mobile sources, but in the later periods ar ea sources will become a more dominant fraction. For NOx emissions, mobile sources are expected to be the dominant source through the entire period.Chapter 5 Future Air Quality

5 - 25 TABLE 5-6 Emissions Carrying Capacity Estimations for the South Coast Air Basin (tons/day) based on the Planning Inventory

a) Carbon Monoxide Attainment Strategy to meet NAAQS (2003) Emission Category CO
Point 47 Area 323 On-Road 3088 Off-Road 1040 Overall Control Strategy 4497
b) PM 10 Attainment Strategy to meet NAAQS (2006) Emission Category VOC NOx SOx PM10
Point 65 48 16 13
Area 216 46 1 238 On-Road 252 549 5 19 Off-Road 139 291 36 21 Overall Control Strategy 673 935 57 291
c) Ozone Attainment Strategy to meet NAAQS (2010) Option-1 Emission Category VOC NOx
Point 67 50 Area 113 33 On-Road 65 256 Off-Road 65 190 Overall Control Strategy 310 529
d) Ozone Attainment Strategy to meet NAAQS (2010) Option-2 Emission Category VOC NOx
Point 67 50
Area 113 33 On-Road 66 270 Off-Road 67 244 Overall Control Strategy 313 597Final 2003 AQMP

5 - 26 

### 0 200 400 600 800 1000 1200 1400

1997 2002 2006 2010
YearTons Per Day

Point Sources Area Source On-Road Mobile Off-Road Mobile

FIGURE 5-14
VOC Emissions - Baseline Scenario



### 0 200 400 600 800 1000 1200 1400

1997 2002 2006 2010
YearTons Per Day

Point Sources Area Source On-Road Mobile Off-Road Mobile

FIGURE 5-15 VOC Emissions - Under 2003 AQMP: Option-1* * Under Option-2, the VOC emissions are maintained at the same level.Chapter 5 Future Air Quality

5 - 27 

### 0 200 400 600 800 1000 1200 1400

1997 2002 2006 2010
YearTons Per Day

Point Sources Area Source On-Road Mobile Off-Road Mobile

FIGURE 5-16
NOx Emissions - Baseline Scenario



### 0 200 400 600 800 1000 1200 1400

1997 2002 2006 2010
YearTons Per Day

Point Sources Area Source On-Road Mobile Off-Road Mobile

FIGURE 5-17 NOx Emissions - Under 2003 AQMP: Option-1* * Under Option-2, NOx emissions would be raised by 68 tons per day.