IMS-004/PS-2 Portland Study Interim Analysis: Update with Nine Months of Vehicle Operation May 1979 Inspection and Maintenance Staff Emission Control Technology Division Office of Mobile Source Air Pollution Control Office of Air, Noise, and Radiation U.S. Environmental Protection Agency ------- Introduction This is the third in a series of interim reports on EPA's Portland Study, a large scale passenger car testing program designed to study the Oregon Motor Vehicle Inspection Program. The study, which is currently in progress, has as its primary goal the evaluation of the costs and effectiveness of an ongoing inspection and maintenance (I/M) program. The first report, issued in May 1978, was a brief report, highlighting I/M's immediate effectiveness following maintenance and the costs of repairs. The second report, issued in January 1979, covered the study design and background more extensively than did the first report, and also included much more data analysis. Two of the key questions regarding I/M are 1) the effectiveness of a short test in identifying vehicles which are polluting excessively; i.e., are in need of remedial maintenance, and 2) the amount and duration of emission reduction obtained immediately after maintenance is performed on failed vehicles. These two questions were addressed in the second interim report using data from the first six months of the program. More extensive data are now available. The present report will be a brief follow-up of the analysis contained in the second report, focusing primarily on the above two questions. The second interim report, which is available from the inspection maintenance staff, should be referenced for background and study design information, as well as for information on questions which are not covered in the present report. The final report on the Portland Study is expected to be completed in about six months. In the meantime, requests for further information should be addressed to Janet Becker (313-668-4351). Summary Based on data for 1975-77 model year cars in the Portland Study, substantial reductions in emissions due to I/M are observed through three quarters of a year. Specific conclusions are as follows: (1) At a failure rate of 35%, the Oregon DEQ state inspection test successfully identified the worst emitters of FTP HC and CO. The average FTP CO level of the failed vehicles was three times that of passed cars. The average FTP HC level of the failed cars was more than twice that of the passed cars. (2) The state inspection test identified as needing maintenance 56% of all excessive FTP HC and CO emitters. These failed vehicles accounted for 80% of the FTP HC and CO emissions which were in excess of the Federal standards. (3) For the I/M fleet (Portland vehicles), mean FTP HC had deteriorated to the pre-maintenance level by the third quarterly retest; however, it is still below that of the non-I/M fleet (Eugene vehicles). Mean FTP CO is still below the pre-maintenance level at the third quarterly retest. ------- -2- Discussion This analysis is being prepared based upon data available from the Portland Study as of April 11, 1979. The effort to address short test effectiveness in identifying excessive polluters was complete. A total of 2,207 1975-77 model year cars have been tested. Approximately 500 of these vehicles had been tested over nine months' time to determine the duration of I/M effectiveness. The goal of the study is 600. The distribution of the 500 cars by model year and pass/fail status is given in Table 1. Since the analysis is incomplete, estimates and tentative conclusions are subject to revision. This report presents data on vehicles through the first three quarters. At completion, data will be presented for cars through four quarters. (Once analysis is completed on the fourth quarterly results another interim report will be issued.) Also, results for the 1972-74 model year vehicles are not presented here due to the lack of appropriate estimates to weight the results to make them representative of the Portland area vehicle population. An attempt is being made to develop these weights; in the meantime, the six month interim report should be referenced. Short Test Effectiveness An indication of the Oregon Department of Environmental Quality's (DEQ) short test effectiveness in identifying high FTP emitters is given in Figures 1 through 3. The DEQ short test consists primarily of an idle test, but also includes a brief physical inspection. Based on the 2,207 vehicles in 1975-77 model year sample, vehicles experienced a 35% failure rate at the state inspection lane. This failure rate agrees closely with that observed by the Oregon DEQ for all 1975 and later model year cars in the Portland area. As is seen in the figures, mean FTP HC and CO emissions are much higher for failed than for passed cars (three times as high for CO and more than twice as high for HC). This indicates that the DEQ test is successful in classifying cars as high or low emitters of FTP HC and CO. The Oregon inspection test is not designed to identify high emitters of FTP NOx and, as is seen in Figure 3, there is practically no difference in mean NOx emissions between the passed and failed cars. From an air quality standpoint, only 56% of the FTP failures are caught, however, 80% of the FTP HC and CO emissions in excess of the Federal standards are identified. This means that in general the I/M test catches the worst emitters while letting the more marginal emitters get by. Emission Deterioration over Nine Months Since the last interim report on the Portland Study, sufficient data have been obtained and sufficient analysis has been performed to make estimates of emission deterioration through three quarterly retests ------- -3- (approximately nine months following the initial inspection). These results are presented in Table 2 and Figures 4 through 7.* Over nine months, FTP CO deterioration for the I/M fleet remains fairly linear and only slightly steeper than for the non-I/M fleet; however, FTP HC deterioration is substantially steeper than the non-I/M fleet's deter- ioration, especially during the second and third quarters. Idle emission deterioration between the second and third quarters does not follow the same pattern as the corresponding FTP deterioration, as illustrated in Figures 4 and 5. It is seen that in nine months, mean FTP HC emissions for the Portland fleet have deteriorated to the pre-maintenance level, however, are still below the non-I/M fleet level. As seen in Table 2, the failed cars which received maintenance have not returned to their pre-maintenance levels. Mean FTP CO emissions for the Portland fleet remain below pre-maintenance levels at the third quarterly retest. * It is noted that the six month data presented in this report do not exactly match the six month results presented in the second interim report. This is to be expected. Different groups of vehicles had completed three quarterly retest sequences than had completed two quarterly retest sequences as of the last report. Also, the weights used to make the sample estimates more representative of the Portland population have been improved by the addition of more data. ------- Table 1 Number of Test Sequences Completed by I/M Study Vehicles (as of 11 April 1979) Retest After First Second Third Fourth. Initial Maintenance Quarterly Quarterly Quarterly Quarterly* 113 123 106 95 134 117 113 126 108 121 94 114 98 113 106 107 91 105 93 95 103 101 84 88 88 78 97 94 77 83 80 75 Portland, Model Years 72-74, passed Portland, Model Years 75-77, passed Portland, Model Years 72-74, failed Portland, Model Years 75-77, failed Eugene, Model Years 72-74 Eugene, Model Years 75-77 *Fourth quarterly results have not been included in this report. ------- Table 2 Odometer (Miles) Idle HC** (ppm) Idle CO** (%) FTP HC (gpm) FTP CO (gpm) FTP NOx (gpm) Ongoing Effects of I/M* 1975-77 Model Year Cars Portland Pass Portland Fail Initial 23257 70 .24 1.20 11.93 2.60 First Quarterly 26629 91 .33 1.21 12.07 2.77 Second Quarterly 29468 116 .48 1.28 13.54 2.64 Third Quarterly 32051 104 .53 1.55 14.56 2.60 Initial 24660 311 3.03 2.87 40.63 2.29 After Maintenance 25506 84 .16 1.64 20.51 2.36 First Quarterly 28218 138 .66 1.85 24.30 2.27 Second Quarterly 31079 196 1.06 2.28 24, 96 2.35 Third Quarterly 33807 176 1.11 2.32 27.79 2.40 * All numbers have been weighted to give best estimates for the Portland tri-county vehicle population. Eugene vehicles do not undergo I/M but are matched to the Portland sample and weighted to represent the Portland population in the absence of I/M. ** Based on measurements taken at the contractor's lab. The lower of the two curb idle measurements was used as the idle level for each car. ------- Table 2 (continued) Portland Composite Eugene Initial 23763 157 1.25 1.80 22.28 2.49 After Maintenance 24068 75 .21 . 1.36 15.03 2.51 First Quarterly 27202 108 .45 1.44 16.48 2.59 Second Quarterly 30049 145 .69 1.64 17.66 2.54 Third Quarterly 32684 130 .75 1.83 19.33 2.53 Initial 22668 163 1.37 1.98 25.79 2.71 First Quarterly 26248 188 1.66 2.00 26.83 2.63 Second Quarterly 29641 187 1.59 2.02 27.84 2.45 Third Quarterly 33828 193 1.38 2.09 27.76 2.69 ------- Figure 1 Mean FTP CO Emissions for 1975-77 Model Year Vehicles Passing and Failing the DEQ Inspection 30 o a o 20 10 FfllL 35X OEQ INSPECTION PflSS 65X (N-2207) ------- Figure 2 Mean FTP HC Emissions for 1975-77 Model Year Vehicles Passing and Failing the DEQ Inspection 3.0 2.5 2.0 Q_ O 1.5 O z: o_ ti.o 0.5 0.0 FfllL 35% DEQ INSPECTION PflSS 65X CN-2207) ------- Figure 3 Mean FTP NOx Emissions for 1975-77 Model Year Vehicles Passing and Failing the DEQ Inspection 3.0 2.5 2.0 C9 X o 1.5 0.5 0.0 FfllL PflSS 35X 65X DEQ INSPECTION (N-2207) ------- Figure 4 Ongoing Effects: • 1975-77 Model Year Portland Population Estimated Means VEHICLES HITM THREE QUARTERLIES 200 175 150 •125 » » t 100 75 50 25 0 o UJ PORTLAND EUGENE 22000 2*iOOO 28000 26000 MILEAGE 30000 32000 34000 ------- Figure 5 Ongoing Eff.ects: 1975-77 Model Year Portland Population Estimated Means 2.0 VEHICLES WITH THREE QUARTERLIES 1.5 o UJ 1.0 0.5 0.0 PORTLflNO EUGENE 22000 24000 26000 28000 30000 32000 34000 MILEAGE ------- Figure 6 Ongoing Effects:' 1975-77 Model Year Portland Population Estimated Means VEHICLES KITH THREE OURRTERLIES 2.50 2.00 £1.50 o 1.00 0.50 0.0 PORTLflNO EUGENE 22000 24000 26000 28000 30000 32000 34000 MILEflOE ------- Figure 7 Ongoing Effects:' 1975-77 Model Year Portland Population Estimated Means 30 25 VEHICLES WITH THREE OURRTERLIES 15 LIO PORTLAND EUGENE 22000 24000 26000 28000 HILERGE 30000 32000 3*000 ------- |