Traffic emissions

This alarming observation in terms of the survival of businesses and respect for the environment calls for a breakthrough transformation in doing business at all levels in the value chain in the direction of better balance, transparency, responsibility and collaboration between stakeholders. Vigorous step changes are needed to significantly reduce CO2 emissions, traffic... 

In densely populated areas, traffic is responsible for massive exhausts of nitrous oxides, soot, polyaromatic hydrocarbons, and carbon monoxide. Traffic emissions also markedly contribute to the formation of ozone in the lower parts of the atmosphere. In large cities, fine particle exposure causes excess mortality which varies between one and five percent in the general population. Contamination of the ground water reservoirs with organic solvents has caused concern in many countries due to the persistent nature of the pollution. A total exposure assessment that takes into consideration all exposures via all routes is a relatively new concept, the significance of which is rapidly increasing. 

CALINE3 (California Line Source Model) is a line source dispersion model tliat can be used to predict carbon monoxide concentrations near liighways and arterial streets given traffic emissions, site geometry, and meteorology. 

APRAC-3 contains the emission factor computation mcdiodology and treats traffic links in die primary network with low vehicle miles traveled as area sources. 

When enrichment episodes occur in the real world, but not in the laboratory under federal certification tests, real-world emissions are significantly higher than predicted. Further complicating emissions prediction is that aggressive driver behavior and complex traffic flow characteristics play a large role in enrichment occurrence. Current vehicle activity simulation models can predict average speeds and traffic volumes very well, but poorly predict the hard-accel-eration events that lead to enrichment. 

MODELING THE EMISSIONS IMPACTS OF TRAFFIC FLOW IMPROVEMENTS... 

Georgia Institute of Technology Emission Control, Vehicle Traffic Flow Management... 

The average life of a car is 10 years. New car sales amounted to 368,000 units in the MCMA in 1989, compared to 136,000 in 1984. Vehicular transportation accounts for 22.4 million personal journeys a day 51% are taken to go to work, 24% to school, 8% for shopping, 3% for entertainment, and 14% in other activities. Although 79.4% of personal journeys are made by public transport, those 19.0% related to the use of private cars are sufficient to create traffic jams, low transit speeds and 70.4% of vehicular emissions. 

Since man-made emissions of CO are dominated by releases from motor vehicles. It Is considered that global emissions have risen along with the rapid growth In vehicle numbers since the 1940s. In the US for example, the number of motor vehicles Increased by a factor of 4 between 1940 and 1970 while the CO emissions rose from 73 to more than 100 million tons per year over the same period (24). Since about the m1d-70s, control strategies have been Initiated which have resulted In reductions In CO emissions. The outcome of these controls has been a gradual decrease of CO emissions In North America and some Western European countries despite Increases In traffic density. For example In the USA, emissions have declined by approximately 1.5% per year since 1975, which by 1984 represented an overall decrease of more than 11 million tons. 

Today s society asks for technology that has a minimum impact on the environment. Ideally, chemical processes should be clean in that harmful byproducts or waste are avoided. Moreover, the products, e.g. fuels, should not generate environmental problems when they are used. The hydrogen fuel cell (Chapter 8) and the hydrodesulfurization process (Chapter 9) are good examples of such technologies where catalysts play an essential role. However, harmful emissions cannot always be avoided, e.g. in power generation and automotive traffic, and here catalytic clean-up technology helps to abate environmental pollution. This is the subject of this chapter. 

Motor vehicle traffic is the main source of anthropogenic lead (Pb) emissions. In humans, toxication causes damage to the nervous system and the kidneys along with other harmful effects (Merian 1991). Lead is preferably absorbed by grass and rape seed. Its content reaches values of more than 5 mg kg-1, while the average lead content of the other plant species is relevantly lower and in some cases below the detection limit. 

Low-level exposures to -hexane can possibly occur for much of the United States population, especially those that live in urban areas or those that commute in areas with heavy traffic, due to emissions of -hexane associated with motor fuel use. As such, the general population will be exposed to very low levels at all times, while those living in urban centers may be exposed to slightly higher levels. 

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