Appendix F-1
Inventory Comparison - 2007/2008/2025
The 2007, 2008 and 2025 emission inventories were evaluated to show that the 2007 emission
inventory is an appropriate and representative emission inventory to use as a surrogate attainment
emission inventory for the 2008 emission inventory for the Pennsylvania portion of the PhiladelphiaWilmington PA-NJ-DE PM2.5 nonattainment area for the 2006 24-hour PM2.5 National Ambient Air
Quality Standard (NAAQS). The 2007 and 2025 emission inventories were developed for MARAMA in a
regional effort that Pennsylvania participated in to refine the emissions inventory and to compile a
regional emissions inventory. See Appendix C for detailed inventory methodology information for 2007
and 2025 inventories. Emissions for point, area and nonroad sectors for the 2008 emission inventory
are from the 2008 National Emissions Inventory (NEI) Version 2. Emissions for the highway vehicle
sector for 2008 were generated using the MOVES model. A detailed methodology description for the
MOVES model is available in Appendix D.
A summary of the 2007, 2008 and 2025 emission inventories is displayed in Table 1. The inventory
analysis shows that the 2007 emission inventory is comparable to the 2008 emission inventory for the
Pennsylvania portion of the Philadelphia PM2.5 nonattainment area. PM2.5, SO2, NOx and NH3 are
lower in 2008 by 2.2%, 15.5%, 11.1% and 4.4%, respectively. VOC emissions are higher in 2008 by 1.9%.
A comparison of the MARAMA 2007 inventory to the MARAMA 2025 inventory shows a decrease in
PM2.5, SO2, NOx, VOC and NH3 emissions from 2007 to 2025. A comparison of the 2008 NEI to the
MARAMA 2025 inventory also shows decreases in PM2.5, SO2, NOx and VOC. In the 2008 to 2025
inventory comparison, NH3 emissions increase slightly by 1.3%, which is not a concern because
ammonia emission are very small compared with other pollutant emissions.
The inventory analysis shows that a decreasing trend in emissions is anticipated through 2025 from a
2007 inventory base year and from a 2008 inventory base year. Therefore, both the 2007 and 2008
emission inventories satisfy the maintenance demonstration criteria provided in EPA guidance that a
state may demonstrate maintenance of a NAAQS by showing that future projected emissions are less
than or equal to the attainment year. ((See, EPA, “Procedures for Processing Requests to Redesignate
Areas to Attainment,” John Calcagni (September 4, 1992) (Calcagni Memo)).
Table 1 Comparison of 2007/2008/2025 Emission Inventories
2007
Point
Area
Highway Vehicle
Nonroad
2007 TOTAL
PM2.5
2,522
7,722
2,386
1,562
14,192
SO2
19,633
15,005
508
3,375
38,520
NOX
20,744
12,925
69,327
20,393
123,390
VOC
6,281
47,568
29,293
18,751
101,894
NH3
743
3,293
1,270
23
5,329
2008
Point
Area
Highway Vehicle
Nonroad
2008 TOTAL
PM2.5
1,545
9,007
2,155
1,176
13,883
SO2
16,209
15,589
418
317
32,534
NOX
19,090
14,953
62,890
12,770
109,703
VOC
5,784
51,004
26,910
20,173
103,871
NH3
587
3,309
1,183
15
5,094
2025
Point
Area
Highway Vehicle
Nonroad
Emission Reduction Credits
2025 TOTAL
PM2.5
1,887
7,047
1,145
897
650
11,626
SO2
5,858
9,186
259
532
6,361
22,197
NOX
11,316
12,675
23,056
11,494
5,198
63,738
VOC
6,506
44,530
11,222
12,193
1,086
75,536
NH3
789
3,436
908
29
0
5,162
Difference Between 2007 and 2008
% Difference Between 2007 and 2008
PM2.5
-309
-2.2
SO2
-5,987
-15.5
NOX
-13,687
-11.1
VOC
1,977
1.9
NH3
-234
-4.4
Difference Between 2007 and 2025
% Difference Between 2007 and 2025
-2,567
-18.1
-16,324
-42.4
-59,651
-48.3
-26,357
-25.9
-167
-3.1
Difference Between 2008 and 2025
% Difference Between 2008 and 2025
-2,257
-16.3
-10,337
-31.8
-45,965
-41.9
-28,334
-27.3
67
1.3