EVALUACIÓN DE CONTAMINANTES EN MICROBUSES Y AUTOBUSES EN EL DISTRITO FEDERAL UTILIZANDO EL SISTEMA RAVEM A BORDO

Abstract

The RAVEM system (Ride Along Vehicle Emissions Measurement) is one of the PEM (Portable Emissions Measurement) developed in recent years. The PEM are systems which measure the emissions generated by automotive vehicles. The development of this measurement technology was leaded by the US EPA in late 90’s. The RAVEM systems was used to measure the pollutant emissions (CO, CO2, NOx and PM10) on board of concessionaired microbuses and public city buses, used for passenger’s transportation, along 4 years in Mexico City streets and were collected 182 tests in 35 vehicles. For the microbuses, most of the test were performed in vehicles using LPG as fuel, and is this stratum which shows the greatest variation for particulates, nitric oxide and carbon dioxide. For the carbon monoxide the greatest variation is for the microbuses that use gasoline as fuel. In the case of buses, the particulate matter and carbon monoxide tests showed the greatest variation corresponded to the bus EPA 1998 of 11.4 m of length using conventional diesel fuel. In the case of CNG buses, the greatest variations were in the emissions of the evaluated gaseous pollutants. In the case of the LPG microbuses, which is the most popular fuel used by this type of vehicles, in general, the measures made with the RAVEM system report grater emissions by traveled kilometer (between 50% & 90%) than the emission factors used to estimate the Emission Inventory for the Mexico City Area in 2006. For the buses, the test results are more dispersed, since in most of the vehicles the particulate and carbon monoxide emissions, the Emission Inventory´s emission factors are greater than the emissions measured with the RAVEM system, on contrary are the emissions for nitric oxide and carbon monoxide.