# Appendix F

Effect of Senior Exemption on 2002 Highway Mobile Source EmissionsEffect Of Senior Exemption on 2002 Highway Mobile Source Emissions

During their 1996 session the Georgia General Assembly amended the Georgia Motor Vehicle Emission Inspection and Mainte nance Act (O.C.G.A . Section 12-9, et seq ), to exempt from emission testing those otherwis e subject vehicles te n years old or older driven fewer than 5,000 miles per year and owned by persons 65 years old or older.

The actual numbers of vehicles that received senior citizen exemptions from Georgia's inspection and maintenance (I/M ) program waiver centers in 2002 are shown in the table below (source: Appendix I, Detailed List of Waivers Processed, from 2002 Annual Operations Report for Georgia's Enh anced Inspection and Maintenance Program , July 30, 2003):

AGE VEHICLES

10 years 1,629

11 years 2,120

12 years 2,239

13 years 2,630

14 years 2,496

15 years 2,350

16 years 2,369

17 years 2,227

18 years 1,708

19 years 1,111

20 years 669

21 years 586

22 years 496

23 years 833

24 years 794

25 years 44

F-12002 NO

x Credit Loss

MOBILE6.2 emission factors for calculating the 2002 NO

x credit loss from these exempted vehicles were determined in the following manner. Six combined highway mobile source control strategies were modeled:

• enhanced I/M in all 13 Atlanta ozone nonattainment area counties;

• the Federal Motor Vehicle Control Program , including Tier 1 and Tier 2 tailpipe standards;

• Stage II vapor recovery;

• low-sulfur (150 parts per million, or ppm) and low Reid Vapor Pressure (7.0 pounds per square inch, or psi) gasoline;

• the National Low Emission Vehicle (NLEV) program; and

• technician training a nd certification).

The enhanced I/M program is a decentrali zed annual hybrid with onboard diagnostics (OBD-II) system checks on 1996 and newer model year vehicles; and two-mode ASM tests on 25-year-old through 1995 model year vehicles. Anti-tampering inspections (checking for catalyst remova l) are performed on 25-year -old through 1995 model year vehicles, and gas cap pressure tests are performed on all vehi cles subject to inspection.

• An overall 2002 highway mobile source NO inventory based on July 1, 2002,

MOBILE6.2 emission factors with all c ontrols in place (310,382,142 grams per day) x

was divided by the total summer-adj usted 2002 VMT (122,754,275 miles) with a resulting overall grams-per-mile NO emission factor of 2.528.

x

• MOBILE6.2 runs with all subject vehicles receiving their appr opriate test were performed to determine the speed th at would result in a July 1, 2002, NO emission factor of 2.528 grams per mile: 38.58 miles per hour. x

• Two separate July 1, 2002, MOBILE6.2 r uns, at 38.58 mph and with emissions calculated by model year, were made: one with hybrid I/M on 25-year-old and newer subject vehicles; the other with OBD-II system checks on 1996 and newer vehicles, with 1995 and older vehicles exempted.

• Next, both sets (covered and exempt) of em ission factors were separately multiplied by the VMT fractions, 1 normalized to total 1.000, for the appropriate vehicle types (LDGV, LDGT12, LDGT34), and the three prod ucts were then added together to produce a single passenger vehicle emission f actor for each exempted vehicle age.

• The differences in the covered and exempt emission factors were then determined for each exempted vehicle age, these differences were multiplied by 4999, the maximum allowable yearly miles traveled by exem pt vehicles, and that product was then

1 An output of MOBILE6.2, the VMT (vehicle mile s traveled) fraction is the fraction of total VMT traveled by each vehicle type.

F-2multiplied by the number of vehicles of that age to determine grams per year. Grams per year were converted to tons per day (907,180 grams per ton, 365 days per year) and the resulting NO reduction credit loss for 2002 wa s determined to be 0.03 ton per day. x

2002 VOC Credit Loss

MOBILE6.2 emission factors for calculat ing the 2002 VOC credit loss from these exempted vehicles were determined in the following manner:

• An overall 2002 highway mobile sour ce VOC inventory based on July 1, 2002,

MOBILE6.2 emission factors with all c ontrols in place (158,026,372 grams per day) was divided by the total 2002 VMT (122,754,275 miles) with a resulting overall grams-per-mile VOC emission factor of 1.287.

• MOBILE6.2 runs with all subject vehicles receiving their appr opriate test were performed to determine the speed that would result in a July 1, 2002, VOC emission factor of 1.287 grams per mile: 30.6 miles per hour.

• Two separate July 1, 2002, MOBILE6.2 r uns, at 30.6 mph and with emissions calculated by model year, were made: one with hybrid I/M on 25-year-old and newer subject vehicles; the other with OBD-II system checks on 1996 and newer vehicles, with 1995 and older vehicles exempted.

• Next, both sets (covered and exempt) of em ission factors were separately multiplied by the VMT fractions, normalized to tota l 1.000, for the appropriate vehicle types (LDGV, LDGT12, LDGT34), and the three prod ucts were then added together to produce a single passenger vehicle emission f actor for each exempted vehicle age.

• The differences in the covered and exempt emission factors were then determined for each exempted vehicle age, these differences were multiplied by 4999, the maximum allowable yearly miles traveled by exem pt vehicles, and that product was then multiplied by the number of vehicles of that age to determine grams per year. Grams per year were converted to tons per day (907,180 grams per ton, 365 days per year) and the resulting VOC reduction credit loss for 2002 was determined to be 0.05 tons per day.

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