Emission Characteristics of Mexico City Vehicles

The University of Denver remote sensor for automobile exhaust was set up for nine days at five locations in the Mexico City area. A total of 31,838 valid readings for CO and HC emissions were obtained. The emissions distribution was unlike any other we have observed in North America or Europe, in that the emissions for both CO and HC were vastly greater than seen elsewhere. The readings are discussed in terms of the fraction of CO and HC which would be measured by a tailpipe probe, and in terms of grams emitted per gallon of gasoline. The median CO emission was 3.8 percent, with half of the CO emissions coming from the 24 percent of the fleet with over 6.6 percent CO in the exhaust. The median HC emission was 1,100 parts per million measured as propane equivalent, while half the emissions come from twelve percent of the fleet with more than 4,000 ppm propane equivalent in the exhaust

The rotational and fine-structure spectrum of FeH, studied by far-infrared laser magnetic resonance

Transitions between the spin-rotational levels of the FeH radical in the υ=0 level of the X4Δ ground state have been detected by the technique of laser magnetic resonance at far-infrared wavelengths. Both pure rotational and fine-structure transitions have been observed; lambda-type doubling is resolved on all the observed transitions. The energy levels of FeH are strongly affected by the breakdown of the Born-Oppenheimer approximation and cannot be modeled accurately by an effective Hamiltonian. The data are therefore fitted to an empirical formula to yield term values and g factors for the various spin-rotational levels involved. Many of the resonances show a doubling that arises from the proton hyperfine structure

Worldwide On-Road Vehicle Exhaust Emissions Study by Remote Sensing

The remote sensing technology developed by the University of Denver provides the first practical approach to routinely characterize real-world, on-road auto-mobile CO and HC exhaust emissions. It has been used to measure the exhaust emissions of more than 1000 000 vehicles in many locations. This study presents an analysis and comparison of 22 fleet profiles collected by the remote sensor in different regions around the world. Three patterns of emissions distributions and contributions of the fleets are revealed by a hierarchial cluster analysis. The importance of vehicle maintenance on average CO and HC emissions is revealed by a quintile analysis. Good maintenance practices in Gothenburg, Sweden, contrast with other locations such as Los Angeles, CA, and Melbourne, Australia. The absolute emissions differences between well- and badly maintained vehicles of any age are considerably larger than observable effects of emission control technology and vehicle age

Enhancement of Remote Sensing for Mobile Source Nitric Oxide

A nitric oxide (NO) detector was developed and integrated into the original carbon monoxide (CO) and hydrocarbon (HC) remote sensing system developed by the University of Denver. The system is capable of measuring the CO, HC, and NO exhaust emissions of thousands of on-road vehicles per day. Analysis of a typical field measurement in Denver shows CO, HC, and NO emissions have similar statistics which can be well represented by a gamma distribution. The fraction of NO high emitters tends to increase with age, apparently arising from deterioration of the emissions control system. This paper presents the inverse relationship between NO and either CO or HC emission

On-Road Evaluation of Inspection/Maintenance Effectiveness

This study presents an evaluation of inspection and maintenance (I/M) programs in terms of their effect on motor vehicle carbon monoxide (CO) and hydrocarbon (HC) exhaust emissions as measured on-road by remote sensing technology. The results show that the performance of past I/M programs at several monitored locations has been less effective than predicted by the U.S. Environmental Protection Agency. The emissions from I/M and non-I/M vehicles measured in Tucson, AZ, and in rural Colorado show no statistically significant difference. An apparent I/M effect observed in El Paso, TX, and in Denver, CO, is smaller than predicted. Comparisons of CO emissions by vehicle age for several years at the same locations in Chicago and Denver show no evidence that the Chicago centralized I/M program was more effective than the Denver decentralized I/M program