| Abstract
| - The Inspection/Maintenance Program in the MetropolitanArea of Mexico City (MAMC) mandates a test every 6months for all gasoline motor vehicles as one of the strategiesto decrease emissions of vehicular pollutants. FTP-75and ASM procedures were performed in our facilities toa fleet of 108 in-use motor vehicles before and after theapproval of the I/M mandatory test. When our laboratory-simulated ASM data were compared with those of the officialcertificate, a large difference was observed betweenthem. On the other hand, audits at the test-only centersindicate poor maintenance of the analytical instruments anddynamometers. On the basis of our FTP results, anestimation of the emissions change for the MAMC fleetshows a net 4% decrease in CO emissions, while totalhydrocarbons and NOx increased 9 and 8%, respectively.Our results indicate that the I/M system in the MAMC lacksthe technical capability and investment to ensure thatsoftware and hardware are properly maintained, calibrated,and upgraded. Sometimes limited attention is paid toensure adequate training of inspectors, auditors, and qualitycontrol staff.
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