Real-world measurements of exhaust and evaporative emissions in the Cassiar tunnel predicted by chemical mass balance modeling

Article Abstract:

The sources of pollution in the Cassiar tunnel in Vancouver, BC, were determined using the chemical mass balance model, with focus on the emission profiles of non-methane hydrocarbons. There were higher concentrations of unburned components of exhaust gases than the combustion components for light-duty vehicles. In contrast, combustion components were highest from the on-road benzene emissions, while evaporative sources comprised about 10% of the total on-road emissions. Estimates of total NMHC emission factors as predicted by the CMB model are presented and compared with the results of previous tunnel experiments.

Environmental aspects, Gasoline, Hydrocarbons

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Remote emissions testing hits the road

Article Abstract:

Many states have begun using on-road auto emissions detectors in addition to vehicle inspection and maintenance (I/M) programs to meet the requirements of the Clean Air Act Amendments of 1990. Donald H. Stedman, inventor of the detectors, says the technology is more effective, efficient, affordable and convenient than stationary tests for monitoring vehicle emissions. However, some EPA officials believe that mobile detectors are no substitute for I/M programs because of several limitations. Unlike stationary I/M testing, the detectors do not monitor emissions under real-life conditions.

Evaluation, Automobiles, Pollution control equipment, Automotive pollution control equipment

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Procedures for formation of composite samples from segmented populations

Article Abstract:

Composite sampling is a popular method used for analyzing contaminated samples because it provides a single measure for a combined samples. Composite samples can be formed through homogenization of individual components that have different weights and combining the equal amounts of the homogenates. The level of contamination in the sample is determined by estimating the mean contaminant concentration in proportion with the size of the contaminant. Estimates of variance for the different segments are obatined using specially-designed studies.

Methods, Analysis, Composite materials, Environmental monitoring

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