Detection of gaseous pollutants by VNG-Powered vehicles

Nowadays, air pollution is a major environmental concern. Phenomena such as global warming, acid rain, depletion of the ozone layer and photochemical smog are directly related to increased anthropic air pollution. At present, the vehicular emission is one of the most important sources of air pollution. The increasing use of automobiles by modern society is leading to an increase of pollutant emissions, thus creating serious problems for the public health in the urban centers. In Brazil, there is a program that encourages large-scale use of Vehicular Natural Gas (VNG). Due to this program, there are over than 1.5 million VNG-powered vehicles in Brazil. This fuel is composed mainly by methane (about 90%) and it is considered to be the fuel that causes less environmental damage, especially if compared with gasoline or diesel oil. However, due to the remarkable increase in the use of VNG powered vehicles in Brazil, it has been necessary to better understand the environmental impacts caused by the burning of this fuel. In this work, electrochemical detectors were used to measure emissions of CO, NOx and SO2, whereas CO2 Laser-based Photo acoustic Spectroscopy was employed to the study of ethylene (C2H4) emitted by VNG-powered vehicles. Measurements were performed in the exhaust of VNG-powered taxis in the state of Rio de Janeiro. We could notice that most of the VNG vehicles emit CO, NOx, SO2 and C2H4 in the ppmV range. This issue varied with the vehicle conditions of maintenance, as well as with its age, engine rotation speed and the origin of the Natural Gas.