Leaded gasoline impacts

The Ethyl Corporation survived. EPA s phase-out and a series of lawsuits gave Ethyl five years before the full impact of tetraethyl lead s demise went into effect, and Ethyl used the time to diversify. During the 1980s, Ethyl ranked among the 200 largest corporations in America. The company no longer makes tetraethyl lead but contended, as late as February 2001, that research has failed to show that leaded gasoline poses a threat to human health or the environment. 

A few months before Ethyl went on sale, the U.S. Public Health Service stated tetraethyl lead was poisonous and had the potential to produce lead oxide which could affect public health in heavily traveled areas. In 1923, General Motors, financed a study by the U.S. Bureau of Mines on the safety of tetraethyl lead. The bureau issued a report downplaying leaded gasoline s potential adverse impact on public health. 

A calculation of maximum/minimum ratio from the atmospheric input data in Figure 3 yields the following results Pb = 33, Zn = 9, Cd = 17, Cr=1.5, Cu = 5, Ni = 4. We know that the burning of leaded gasoline is responsible for the large increase of Pb. Enormous metal production of Zn and Cd ores as well as refuse incineration are responsible for the increases of these metals. In addition, marine aerosols are an important source of Cd (Li, 1981). Obviously, Cu-Ni production from ores increased during this period but not nearly as much as for Zn-Cd. Also, combustion of fossil fuels contributed somewhat to the increase of Cu and Ni. The main source of Cr is steel and iron manufacturing which appears to not be as important an impact on the atmospheric environment as sources for the other metals. The pollution sources of Cr are minimal as reflected in the balance between riverine input and marine sediment output (Li, 1981). 

Moran, J. B., Lead in Gasoline, Impact of Removal on Current and Future... 

Since lead-containing antiknock additives of leaded gasolines rapidly destroy the activity of the catalytic emission control systems, unleaded gasolines have had to be used in automobiles fitted with this or related systems. However, since using this fuel modification also eliminates one of the main sources of lead emissions to the atmosphere, this trend also has a highly favorable additional impact [11, 12]. Before unleaded gasolines were on the market, it was common to find high lead levels in the core areas of busy cities... 

In 1923, General Motors, financed a study by the U.S. Bureau of Mines on the safety of tetraethyl lead. The bureau issued a report downplaying leaded gasoline s potential adverse impact on public health. 

To be certified, the devices, when installed, had to have met Fleet and Life testing to demonstrate satisfactory performance on at least 25 vehicles for 12,000 miles using regular (fully leaded) gasoline. Tests required besides the emission standards included tests for effects of the device on vehicle driveability and safety sensitivity to backfire, water immersion, and mountain driving impacts on noise, odor, and production of nitric oxides and to insure that it was failsafe in the event of malfunctions. In spite of the awesome nature of this challenge. 

Lead emissions at the tailpipe as recorded in the 1970s, when leaded gasoline had relatively high average lead content of 1.5—1.6 g Pb/gal, were on the order of 20—30 mg Pb/m (Dzubay et al., 1979 U.S. EPA, 1986, Ch. 6). Comparison of concentrations near or at exhaust pipes with those at increasing distances from traffic indicates most deposition and impact occurs at or near roadside. 

As with dry precipitation, a number of factors govern the rate of wet deposition lead removal rates. These include particle size, seasonality, altitude, amount of precipitation, and thermal inversion (Conko et al., 2004 Davidson and Rabinowitz, 1992 Miller and Friedland, 1994). Input rates of lead to the atmosphere affect rainwater lead content. Table 5.4 presents water lead levels for various areas over a broad time frame. There is a clear trend to lower levels with lower anthropogenic impact, and a clear trend with time. Compared to the 1960s and 1970s when leaded gasoline consumption was at a maximum in the United States, later years showed dramatic drops in lead content. 

Chartsias B, Colombo A, Hatzichristidis D, et al. 1986. The impact of gasoline lead on human blood lead First results of the Athens lead experiment. Sci Total Environ 55 275-282. 

The reduction in the lead content of gasoline and the introduction of reformulated gasoline have been very successful in reducing automobile emissions, due to changes in gasoline composition, with further improvements in fuel quality proposed for the early decades of this new millennium. These projections are accompanied by a noticeable and measurable decrease in crude oil quality, and the reformulated gasoline will help meet environmental regulations for emissions for liquid fuels but will be subject to continuous review because of the potential for environmental impact. 

Lead Free Gasoline. The current rapidly developing move toward unleaded gasolines in the United States will have a further impact in enhancing the position of the heavier feedstocks. 

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