### Appendix C

PM2.5 Reasonable Further Progress CalculationsC-1 

### PM2.5 Reasonable Further Progress Calculations

The CAA requires SIPs to provide for steady progress in reducing emissions during the years leading to the attainment date. Th is requirement, added as part of the 1990 amendments, provides a way to measure comp liance prior to the attainment date. U.S. EPA requires that the RFP plan show linear progress according to emission reduction milestones the region establishes for 2009, and every three years thereafter until the attainment year.

For PM2.5, U.S. EPA guidance provides two alternatives for assessing RFP for PM2.5 strategies. The traditional approach assesse s progress for each precursor against the required rate of progress without considerin g how much each precursor contributes to ambient PM2.5 concentrations (the “linear” option). The second uses information gained from the attainment dem onstration modeling to consider how much reductions of each pollutant contribute to attainment (the “equivalency” option). In essence, the relative contribution approach approximates the progress that will be made in improving air quality

1. Linear RFP Calculation Option

The following table assesses progress m ade with the proposed South Coast Plan, including the adopted AQMP, and the pr oposed State Strategy with proposed consensus amendments, using U.S. EPA’s li near reasonable further progress option. The assessment indicates that reductions of directly emitted PM2.5 and NOx do not meet RFP targets in 2009 and 2012 when calc ulated from a 2002 baseline inventory. Reductions of VOC and SOx, however, exceed linear RFP targets in all years. The District’s air quality models indicate that SO x and directly emitted PM10 reductions have a greater impact on ambient PM2.5 levels than ROG reductions and, to a lesser extent, than NOx reductions. The linear approach does not reflect those impacts.

Table 1 Linear Reasonable Further Progress Calculation

Row Calculation Step PM2.5 NOx SOx VOC

1 2002 Baseline Inventory 99 1093 53 844

2 Control Ratio Needed to Show Linear Progress in 2009 (%) 7/12 7/12 7/12 7/12 3 2009 Target Needed to Show Linear Progress (tpd) 92 720 33 625 4 2009 Remaining Emissions with Plan (tpd) 99 813 28 578 5 Projected Shortfall (tpd) 7 93 0 0 6 Control Ratio Needed to Show Linear Progress in 2012 (%) 5/6 5/6 5/6 5/6 7 2012 Target Needed to to Show Linear Progress (tpd) 89 561 25 532 8 2012 Remaining Emissions with Plan (tpd) 92 565 21 505 9 Projected Shortfall (tpd) 3 5 0 0 10 2014 Remaining Emissions with Plan (tpd) 87 454 19 469C-2 2. Equivalency RFP Calculation Option

An RFP evaluation that acc ounts for the differential impa cts that each of the PM2.5 precursors has on ambient concentrations dem onstrates that the pr oposed strategy also allows the South Coast Air Basin to meet RFP targets. The District’s modelers used the results of 2014 modeling, using the strat egy recommended for appr oval, to determine the PM2.5 reduction value of each of the precursor pollut ants and to assess equivalent progress against RFP targets. The Dis trict’s methodology is described below.

The PM2.5 attainment modeling simulati on was conducted using projected emission reductions for control meas ure implementation for 2014 (C EPA scenario 1). The output of the simulation was averaged by component s pecies for the eight validation sites that represent the Basin. Since a 2005 base y ear was used for the PM2.5 modeling, this basin average PM2.5 species profile was then compared to the 2005 data and the difference in concentration between 2014 wit h implementation of the plan and 2005 ammonium sulfate, ammonium nitrate, organic carbon and particulate (metals and elemental carbon) concentrations were calculated. The particulate component difference concentrations were divided by t he emissions reductions for the same period to determine species-specific projected c oncentrations reductions per unit of emission reduction. These ratios were then used to compute NOx-equivalen t weighting factors for converting species-specific inventory val ues to NOx-equivalent inventory values for purposes of comparing RFP targets with proj ected inventory levels on a NOx-equivalent basis. The reason for converting inventor ies to a NOx-equivalent basis is that emissions reductions in some species wi ll exceed RFP targets in 2009 while other species will fall short. On the whole, however, the cumulative reductions across all species will produce PM 2.5 concentration reductions that are generally linear with time and that comply with RFP requirements.

Table 2 summarizes the basin-average conv ersion factors that relate projected emissions reductions with reductions in PM 2.5 concentrations. Due to differences in particle formation rates, reductions in emissions of SOx and directly-emitted PM 2.5 produce much greater reductions in PM 2.5 concentrations than occur with reductions in emissions of NOx and ROG. Table 3 presents the NOx- equivalent weighting factors where the SOx, ROG and PM2. 5 basin-average conversion factors are normalized to that for NOx. These basin-average conver sion factors are then used to convert both RFP target emission invent ories and plan-projected emis sion inventories to NOxequivalent inventories for comparison purpos es as dictated by RFP requirements.

Tables 4 and 5 provide the RFP calculations for the 2002- and 2005 base-years respectively. The tables convert emission in ventories to a NOx-equivalent basis. For the 2002 base year, the 2009 plan-pr ojected inventory falls shor t of the RFP target by 2.8 percent. For the 2005 base year, the plan- projected inventory in 2009 achieves the target reduction and demonstrates complianc e with RFP requirements. Under both alternatives, RFP requirements are satisf ied in 2012. Because the basin-average conversion factors were determined from gridded modeling per formed for the 2005C-3 emission inventory year, this year is t he most appropriate base year for the RFP analysis.

Figure 1 plots the emission inventory totals and the RFP targets under the 2005 base year alternative. When a best fit line is over laid, it is clear that the emissions reductions are taking place in a linear fashion, not clustered or back loaded. This graphic illustrates the intention of the RFP requirement and le nds support that a nominal shortfall of a few percent in near term reductions in 2009 is not inconsistent with the overall annual rate of required emissions reductions.

Table 2 Basin-Average Conversion Factors

Basin-Average Conversion Factors Pollutant Species Species Concentration (ug/m3) PM2.5 EC & Crustal 0.0345 NOX Ammonium Nitrate 0.0035 SOX Ammonium Sulfate 0.0526 ROG Organic Carbon 0.0015

Table 3 Normalized NOx-Equivalent Conversion Factors

Normalized NOx-Equivalent Conversion Factors Pollutant Species NOX Equivalent Factor PM2.5 9.8571 SOX 15.0286 ROG 0.4286

Table 4 2002 RFP Anchor Year

Required Required NOx Equivalent

2002 2009 2012 2014 Annual Change 2002 2009 2012 2014 PM2.5 99 91 88 86 1.0943% PM2.5 976 897 867 848 NOx 1093 719 559 452 4.8872% NOx 1093 719 559 452 SOx 53 34 26 20 5.1887% SOx 797 511 391 301 ROG 844 628 536 474 3.6532% ROG 362 269 230 203 Total 2089 1472 1208 1032 Total 3227 2396 2047 1803 Projected Projected NOx Equivalent 2002 2009 2012 2014 2002 2009 2012 2014 PM2.5 99 99 92 86 PM2.5 976 976 913 848 NOx 1093 819 566 452 NOx 1093 819 566 452 SOx 53 28 21 20 SOx 797 421 313 301 ROG 844 579 505 474 ROG 362 248 214 203 Total 2089 1525 1184 1032 Total 3227 2464 2006 1803C-4 Table 5 2005 RFP Anchor Year

Required Required NOx Equivalent

2005 2009 2012 2014 Annual Change 2005 2009 2012 2014 PM2.5 102 95 89 86 1.3072% PM2.5 1005 936 877 848 NOx 1033 775 581 452 4.6870% NOx 1033 775 581 452 SOx 61 43 29 20 5.6011% SOx 917 646 436 301 ROG 825 669 552 474 3.5455% ROG 354 287 237 203 Total 2021 1582 1251 1032 Total 3309 2644 2131 1803 Projected Projected NOx Equivalent 2005 2009 2012 2014 2005 2009 2012 2014 PM2.5 102 99 92 86 PM2.5 1005 980 904 848 NOx 1033 819 566 452 NOx 1033 819 566 452 SOx 61 28 21 20 SOx 917 425 311 301 ROG 825 579 505 474 ROG 354 248 216 203 Total 2021 1526 1184 1032 Total 3309 2472 1998 1803

Figure 1 RFP Calculations Trend Linear and NOx-Equi valent, 2005 Base Year



# RFP Demonstrations: Actual and NOx

Equivalent Emissions

0 1000 2000 3000 4000

2004 2006 2008 2010 2012 2014 2016tons per day

Actual Required NOx-Equivalent Projected Actual Projected NOx-Equivalent Required Linear (Actual Projected) Linear (NOx-Equivalent Projected)