Report No. EPA 460/3-88-003
Analytical Support for
Emission Factors Development
and Air Quality Assessment

Work Assignment No. 0-01:
Analysis of California
I/M Review Committee Data
Task 1 Report
Supplemental Analysis of
Emissions Reductions and
Post-l/M Deterioration

prepared for:
U.S. Environmental Protection Agency
September 30, 1988
prepared by:

Sierra Research, Inc.
1521 I Street
Sacramento, California 95814
(916) 444-6666

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    Report No. EPA 460/3-88-003
       ANALYTICAL SUPPORT FOR
    EMISSION FACTORS DEVELOPMENT
     AND AIR QUALITY ASSESSMENT

    EPA Contract No. 68-03-3474

     Work Assignment No. 0-01:
       Analysis of California
     I/M Review Committee Data

           Task 1 Report:
      Supplemental Analysis of
      Emissions Reductions and
       Post-I/M Deterioration
           prepared for:

U.S. Environmental Protection Agency
         September 30, 1988
            prepared by:

          Thomas C. Austin
         Thomas R. Carlson
        Kathryn A. Gianolini

       Sierra Research, Inc.
           1521 I Street
        Sacramento, CA 95814
           (916) 444-6666

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1 .   Summary
                       ANALYTICAL SUPPORT FOR
                    EMISSION FACTORS  DEVELOPMENT
                     AND AIR QUALITY  ASSESSMENT

                           Task 1 Report:
                      Supplemental Analysis of
                      Emissions Reductions and
                       Post-I/M Deterioration
                         Table of Contents
2.   Introduction and Methodology 	    5
                                                            \
3.   Results

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                             1.  SUMMARY
During a recent evaluation of the California vehicle inspection and




maintenance program, laboratory tests using the Federal Test Procedure




were conducted before and after repairs at "Smog Check" stations.   A




sample of the repaired vehicles was tested again after being




"recaptured" from customer service.  In order to determine how the




emission reductions achieved under the current California program




might compare to that under alternative programs, EPA requested




further analysis of the California data to calculate the change in




emission reductions achieved on failed vehicles if certain vehicles




were removed from the sample.  The vehicles removed from the sample




were those that were not fully repaired (i.e., vehicles receiving




waivers), those that failed only the underhood (visual or functional)




inspection, and those that failed only the 2500 rpm test.









The results of the analysis are summarized in Figure 1.  As shown in




the figure, when vehicles receiving waivers or vehicles failing only




an underhood inspection are excluded from the sample, the average




emission reduction for the remaining repaired vehicles is higher for




HC and CO and lower for NOx.  This is true both for the initial




emissions reduction and after some period of customer service.

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              Figure 1
  Emissions Reductions
and Post I/M  Deterioration
    All Repaired
     Vehicles
   Excluding
  Waivers &
Underhood-Only
   Failures
   Excluding
    Waivers,
 U. H. -Only Fails.
& 2500-Only Fails
                                 Legend
                          HC
                          Deteriorated

                          CO
                          Deteriorated
                          NOx
                          Deteriorated
                           HC
                           Initial

                           CO
                           Initial
                           NOx
                           Initial
               -2-

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                              Table 1

                  Analysis  of Emissions Reductions
                      and Post-I/M Deterioration
                                          	  Emission  Change  	
                                            HC        CO       NOx
    All  Repaired Vehicles
                               initial    -37.3%    -26.9%     -8.8%
                          deteriorated    -28.4%    -25.8%     -5.5%

    Excluding Waivers
    & Underhood-Onlv Failures
           Idle and/or 2500 Failures
                               initial    -44.7%    -35.3%     -4.9%
                          deteriorated    -30.1%    -30.0%     -1.1%

           Idle Failures Only
                               initial    -43.5%    -34.6%     -5.0%
                          deteriorated    -29.2%    -30.1%     +1.1%
Table 1 presents the results of the analysis in tabular form.  The

initial hydrocarbon emission reduction for repaired vehicles increases

from 37.3% to 44.7% when waivers and underhood-only failures are

excluded.  After experiencing some deterioration in customer service,

the hydrocarbon emission reduction for repaired vehicles increases

from 28.4% to 30.1% when waivers and underhood-only failures are

excluded.



A similar trend is shown for carbon monoxide.  The initial CO emission

reduction for repaired vehicles  increases  from 26.9%  to 35.3% when

waivers  and underhood-only failures are  excluded.  After experiencing

some deterioration in customer  service,  the  CO emission reduction for
                                   3-

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repaired vehicles increases from 25.8% to 30.0% when waivers and




underhood-only failures are excluded.









NOx emission reduction percentages are affected in the opposite




manner.  The initial NOx emission reduction for repaired vehicles




decreases from 8.8% to 4.9% when waivers and underhood-only failures




are excluded.  After deterioration in customer service, the NOx




emission decrease for repaired vehicles changes from 5.5% to 1.1% due




to the exclusion of these  vehicles.









Figure 1 and Table 1 also  indicate that the exclusion of vehicles that




fail  only the  2500 rpm test has no significant effect on the percent




emission reductions achieved  from repaired vehicles.  However, after




deterioration  in customer  service, the NOx emission effect for




repaired vehicles changes  from a decrease of 5.5%  to an increase of




1.1%  due to the  exclusion  of  these vehicles.









The prospect for higher  reductions in HC and CO emissions with the




elimination of waivers is  apparent from the analysis.  The adverse




effect on NOx  reductions is not unexpected as the  exclusion of the




underhood inspection results  in some of the NOx emissions defects




(e.g., disconnected EGR valves) being missed.  Without loaded-mode




testing, tailpipe emission tests are only able to  detect HC and CO




emission problems.  In addition, since some repairs of HC and CO




defects tend to  increase NOx  emissions, there can  be a net increase  in




NOx associated with the  elimination  of the underhood inspection.






                                 -H-H-H-
                                 tl It it
                                  -4-

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                   2.  INTRODUCTION AND METHODOLOGY
Under a contract with the U.S. Environmental Protection Agency (EPA)

for "Analytical Support for Emission Factors Development and Air

Quality Assessment," Sierra Research, Inc. (Sierra) performs a variety

of Work Assignments for the Emission Control Technology Division

(ECTD) of EPA's Motor Vehicle Emissions Laboratory in Ann Arbor,

Michigan.  Work Assignment 0-01 directed Sierra to perform analysis of

California I/M data for the ECTD Technical Support Staff (TSS).   Task

number 1 of that Work Assignment required an evaluation of how

alternative I/M test procedures would affect the emission reductions

achieved from failing vehicles and the post-I/M deterioration of those

vehicles.



The general direction provided by TSS was as follows:

        The Technical Appendix (to Sierra's previous report on the
        California I/M Evaluation Program) shows mean data for 290
        cars that failed their California smog check, were repaired,
        and then retested after a period of deterioration.  The sample
        includes vehicles which may not have been fully repaired, cars
        that failed only for tampering, and vehicles which had
        inconsistent emissions test results between ARB and the smog
        check station(s).  The contractor shall repeat the analysis,
        and any relevant more detailed analysis, for the subset of
        vehicles which were as-received emissions failures at the
        first smog check station (with and without consideration of
        2500 rpm status) and which were emission passes after
        commercial repair.
                                 -5-

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The 290 vehicles referred to above were "undercover" vehicles used in




an ARB-sponsored study to evaluate the emissions effects of the




California Smog Check program.  As described in Sierra's previous




report to ARB ("Evaluation of the California Smog Check Program -




Technical Appendix," April 1987), these 290 vehicles were "repaired"




vehicles that had been "recaptured".  Each vehicle in the sample




received repairs at a Smog Check station and subsequently passed the




test.  In most cases the repair was sufficient to get the vehicle to




pass the I/M standards.  In other cases, the vehicle was not repaired




to the point where tailpipe emission levels met the I/M test standards




and the vehicle received a "certificate of compliance" by virtue of




getting a "waiver".  Sierra's previous analysis showed how the




immediate emission changes associated with repair of these 290




vehicles compared to the emissions after the vehicles were recaptured




from customer service some months later.









Table 2 presents the results  of  Sierra's earlier analysis with the




addition of a column entitled "Weighted Composite".  This new column




presents the average emission results for all model year groups after




they have been weighted to reflect the population and estimated annual




VMT of each model year group.   (The original analysis was for the 290




vehicle sample with no weighting factors applied to reflect annual VMT




differences.)  The weighting  factors were developed from the VMT




estimates contained in Table  8-15  (pg. 118) of Sierra's earlier report




and the frequency of "initial"  tests for various model year groups




computed from a random sample  of Test Analyzer System data.  The




vehicle population was estimated to be 20% pre-1975, 30% 1975-1979,
                                  -6-

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                               Table 2

               Changes in Emissions by Model Year Group
                           For All Vehicles
                     (Immediate and Deteriorated)

HC Emissions (g/mi)
before I/M
after repair
deteriorated
% Emission Changes
initial
deteriorated
CO Emissions (g/mi)
before I/M
after repair
deteriorated
% Emission Changes
initial
deteriorated
NOx Emissions (g/mi)
before I/M
after repair
deteriorated
% Emission Changes
initial
deteriorated
Mean Mileages
baseline
deteriorated
A Mileage
Pre-1975
10.29
5.97
7.66
-42.0%
-25.6%
72.01
63.04
65.83
-12.5%
- 8.6%
3.33
3.07
2.83
- 7.8%
-15.0%
103,359
108,427
5,068
75-79
4.61
3.03
3.59
-34.3%
-22.1%
48.29
39.18
40.36
-18.9%
-16.4%
2.77
2.39
2.50
-13.7%
- 9.8%
86,228
92,996
6,768
Post-1979
2.08
1.37
1.34
-34.1%
-35.6%
34.41
21.83
21.59
-36.6%
-37.3%
1.22
1.15
1.26
- 5.7%
+ 3.3%
50,875
59,147
8,272
1
' All i
5.15
3.19
3.82
-38.1%
-25.8%
49.38
39.08
40.17
-20.9%
-18.7%
2.36
2.12
2.15
10.2%
- 8.9%
78,106
84,975
6,869
Weighted
Composite
3.73
2.34
2.67
-37.3%
-28.4%
42.43
31.03
31.50
-26.9%
-25.8%
1.82
1.66
1.72
- 8.8%
- 5.5%


Sample Size
73
                                    115
102
290
                                  -7-

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and 50% post-1979 models.  Combining the vehicle population fractions

with the annual VMT estimates for each model year group, the

relationship between model year group and travel fraction was computed

to be as follows:
        Model Year Range         Travel Fraction

           pre-1975                  14.1%
           1975-1979                 19.5%
           post-1979                 66.4%

           all                      100.0%
To conduct  the  requested analysis,  it was necessary to eliminate

the following vehicles  from the  full sample of 290 vehicles that

received repairs  at  Smog Check stations:
      O  Vehicles which  failed  only because of a visual or functional
         inspection,  and

      O  Vehicles that were not fully-repaired (i.e., vehicles that
         received "waivers").
After recomputation of the  emissions with these vehicles removed, it

was necessary  to  repeat the analysis after removing vehicles that only

failed the 2500 rpm test.



The results of the  analysis are  contained in the following section of

the report.

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                             3.  RESULTS
As explained in the previous section, to conduct the supplemental

analysis of emission reductions and I/M deterioration, it was

necessary to eliminate certain vehicles from the full sample of 290

vehicles that received repairs at Smog Check stations.  For the first

recomputation of the results:
        sixty-two vehicles were eliminated because they experienced
        underhood failures only, and

        sixty-four vehicles were eliminated because they received
        waivers.
In addition, twenty-five vehicles were eliminated from the sample

because the the failure mode at the Smog Check station could not be

accurately determined.   One more vehicle was eliminated because ARE

apparently lost or never received the data from the after repair test

performed at the Smog Check station.  (In this case, it was not clear

whether a waiver had been issued or not.)
* The total number of vehicles deleted from the full sample was the
same in the draft version of this report.  However, the availability
of a revised and cleaned-up data base from ARE enabled a more accurate
classification of the status of the vehicles that were deleted from
the sample because they were, or may have been, underhood-only
failures, or because they received waivers.

                                 -9-

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Due to the adjustments listed above, the sample size was reduced from

290 to 138.  Recalculation of the emission reductions and post-I/M

deterioration for these 138 vehicles is shown in Table 3.
                               Table  3

               Changes  in Emissions by Model Year Group
                  For Successfully Repaired Vehicles
            Failing  California Idle and/or 2500  Standards
                      (Immediate  and Deteriorated)

HC Emissions ( g/mi )
before I/M
after repair
deteriorated
% Emission Changes
initial
deteriorated
CO Emissions ( g/mi )
before I/M
after repair
deteriorated
% Emission Changes
initial
deteriorated
NOx Emissions ( g/mi )
before I/M
after repair
deteriorated
% Emission Changes
initial
deteriorated
Mean Mileages
baseline
deteriorated
A Mileage
Canvn1 P Si Zfi
Pre-1975
10.07
5.65
8.23
-44.0%
-18.3%
80.10
64.37
65.57
-19.6%
-18.1%
3.08
2.89
2.77
- 6.0%
-10.1%
109,042
113,671
4,629
34
75-79
4.81
2.77
2.95
-42.4%
-38.5%
53.07
37.40
38.49
-29.5%
-27.5%
2.82
2.47
2.59
-12.2%
- 8.2%
86,748
93,514
6,766
47
Post-197?
1.87
1.06
1.27
-43.6%
-32.2%
30.59
16.23
19.04
-46.9%
-37.7%
1.26
1.28
1.36
+ 1.8%
+ 8.0%
50,290
58,859
8,569
57
> All
4.89
2.77
3.56
-42.0%
-26.1%
50.44
35.30
37.13
-30.0%
-26.4%
2.24
2.08
2.12
- 6.9%
- 5.1%
77,182
84,166
6,984
138
Weighted
Composite
3.69
2.04
2.58
-44.7%
-30.1%
41.97
27.16
29.40
-35.3%
-30.0%
1.82
1.73
1.80
- 4.9%
- 1.1%



                                  -10-

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    results from Table 3 are compared to the full 290 vehicle sample

in Table 4.  When vehicles receiving waivers and vehicles failing

only an underhood inspection are excluded from the sample, the average

emission reduction for the remaining repaired vehicles is higher for

HC and CO and lower for NOx.  The initial hydrocarbon emission

reduction for repaired vehicles increases from 37.3% to 44.7% when

waivers and underhood-only failures are excluded.  After experiencing

some deterioration in customer service, the hydrocarbon emission

reduction for repaired vehicles increases from 28.4% to 30.1% when

waivers and underhood-only failures are excluded.



                               Table 4

            Effect of Eliminating Underhood-Only Failures
            and Waiver Vehicles on  I/M Emission Reductions
                                           	 Emission Change 	
                                            HC       CO       NOx
     All Repaired Vehicles
                                initial     -37.3%    -26.9%     -8.8%
                          deteriorated     -28.4%    -25.8%     -5.5%

     Excluding Waivers
     & Underhood-Only Failures
           Idle and/or  2500  Failures
                                initial     -44.7%    -35.3%     -4.9%
                          deteriorated     -30.1%    -30.0%     -1.1%
A similar trend is shown  for  carbon monoxide.   The  initial  CO  emission

reduction for repaired vehicles  increases  from 26.9%  to  35.3%  when

waivers and underhood-only  failures are  excluded.   After experiencing

some deterioration in customer service,  the  CO emission  reduction for
                                  -11-

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repaired vehicles increases from  25.8% to 30.0% when waivers and




underhood-only failures are excluded.









NOx emission reduction percentages are affected in the opposite




manner.  The initial NOx emission reduction for repaired vehicles




decreases from 8.8% to 4.9% when  waivers and underhood-only failures




are excluded.  After deterioration in customer service, the NOx




emission decrease for repaired vehicles changes from 5.5% to 1.1% due




to the exclusion of these vehicles.









Finally, it was necessary to  repeat  the analysis after removing




vehicles that only failed the 2500 rpm test.  There were fourteen such




vehicles in the sample, reducing  the total sample size to 124.  These




results are shown in Table 5.  When  the results shown in Table 5 are




compared to the previous results, it is apparent that the exclusion of




vehicles that fail only the 2500  rpm test has no significant effect on




the percent emission reductions achieved from repaired vehicles.




However, after deterioration  in customer service, the NOx emission




effect for repaired vehicles  changes from a decrease of 5.5% to an




increase of 1.1% due to the exclusion of these vehicles.









The performance of the fourteen vehicles that were 2500 rpm-only




failures is shown in Table 6.  After mileage accumulation in customer




service, these vehicles (all  post-1979 models) had 8.9% lower NOx




emissions than their "before  I/M" levels.  This compares to 12.6%




higher NOx emissions for the  post-1979 models that failed the idle




test (see Table 5) .
                                  -12-

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                Table 5

Changes in Emissions by Model Year Group
   For Successfully Repaired Vehicles
 Failing California Idle Standards Only
      (Immediate and Deteriorated)

HC Emissions ( g/mi )
before I/M
after repair
deteriorated
% Emission Changes
initial
deteriorated
CO Emissions (g/mi)
before I/M
after repair
deteriorated
% Emission Changes
initial
deteriorated
NOx Emissions ( g/mi )
before I/M
after repair
deteriorated
% Emission Changes
initial
deteriorated
Mean Mileages
baseline
deteriorated
A Mileage
Sample Size
Pre-1975
10.07
5.64
8.23
-44.0%
-18.3%
80.10
64.37
65.57
19.6%
-18.1%
3.08
2.89
2.77
- 6.0%
-10.1%
109,042
113,671
4,629
34
75-79
4.81
2.77
2.95
-42.4%
-38.5%
53.07
37.40
38.49
-29.5%
-27.5%
2.82
2.47
2.59
-12.2%
- 8.2%
86,748
93,514
6,766
47
Post-1979
2.13
1.20
1.41
-43.5%
34.1%
34.40
19.16
21.60
-44.3%
-37.2%
1.23
1.23
1.39
- 0.2%
+12.6%
52,208
60,158
7,950
43
All
5.32
3.01
3.86
-43.4%
-27.4%
54.01
38.47
40.06
-28.8%
-25.8%
2.34
2.16
2.22
- 7.8%
- 5.0%
80,883
87,474
6,591
124
Weighted
Composite
3.77
2.13
2.67
-43.5%
-29.2%
44.49
29.10
31.10
-34.6%
-30.1%
1.80
1.71
1.82
- 5.0%
+ 1.1%



                   -13-

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                               Table 6

               Changes in Emissions by Model Year Group
                  For Sucessfully Repaired Vehicles
                        Failing 2500 RPM Only
                     (Immediate and Deteriorated)
                                                            Weighted
                      Pre-1975   75-79   Post-1979   All    Composite
HC Emissions (g/mi)
  before I/M             ---      ---       1.08     1.08
  after repair           	      	       0.64     0.64      	
  deteriorated           	      	       0.90     0.90      	

% Emission Changes
  initial                ---      ---     -40.7%   -40.7%
  deteriorated           	      	     -16.7%    16.7%      	

CO Emissions (g/mi)
  before I/M             ---      ---      18.82    18.82
  after repair           ---      ---       7.22     7.22
  deteriorated           ---      ---      11.18    11.18

% Emission Changes
  initial                ---      ---     -61.6%   -61.6%
  deteriorated           	      	     -40.6%   -40.6%      —

NOx Emissions (g/mi)
  before I/M             ---      ---       1.35     1.35
  after repair           	      	       1.37     1.37      	
  deteriorated           	      —       1.23     1.23      —

% Emission Changes
  initial                ---      ---     + 1-5%   + 1.5%
  deteriorated           ---      ---     - 8.9%   - 8.9%

Mean Mileages
  baseline               	     44,402   44,402
  deteriorated           ---      ---     54,867   54,867

A Mileage                ---      ---     10,465   10,465

Sample Size               0        0        14       14
                                  -14-

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