title: Carbon monoxide trend, meteorology, and three-way catalysts in Mexico City.
abstract: From the analysis of data of the Inspection/Maintenance (I/M) program, and of the long-term trend of ambient CO concentrations in Mexico City, it is inferred that three-way catalysts (TWCs) have a 45% efficiency, well below the expected 90% value. The most probable causes are sulfur poisoning, lead contamination, and ceramic breakage due to bumps and potholes on the streets. Also, we have found a ratio between the average daily peak value of atmospheric CO and gasoline consumption: (11 +/- 1) ppbCO/MLm (million liters of gasoline per month) in 1988 decaying to (10 +/- 1) in 1991 for Mexico City before the introduction of TWCs. In addition, we found a correlation between the monthly averages of CO daily peak and meteorological variables, explaining most of the seasonal changes using only the intensity of the inversion layer and surface wind speed.
authors.affiliation: Instituto de Física, Universidad Nacional Autónoma de México, México, D.F.
authors.forename: H G
authors.initials: HG
authors.lastname: Riveros
authors.forename: A
authors.initials: A
authors.lastname: Alba
authors.forename: P
authors.initials: P
authors.lastname: Ovalle
authors.forename: B
authors.initials: B
authors.lastname: Silva
authors.forename: E
authors.initials: E
authors.lastname: Sandoval
mesh_terms: D000392:Air Movements; D002248:Carbon Monoxide / Q000032:analysis*; D004784:Environmental Monitoring / Q000379:methods*; D008800:Mexico; D018986:Motor Vehicles; D012621:Seasons; D014887:Weather
chemical_list: D002248:Carbon Monoxide