Leaded gasoline phasedown

The relative contribution of mobile source emissions to atmospheric lead levels over the next decade is expected to decrease slightly for two reasons (1) the Federal government s imposition of a phasedown of lead content in gasoline, as called for in regulations promulgated in September 1976 (43) and (2) the incompatibility of leaded gasoline and the catalytic converter introduced in late 1974 for control of regulated (HC, CO, NO,) pollutants (44,45). 

In the first year of reported TEL Pb consumption by the U.S. government, 1941, this figure was 48,000 MT. Succeeding years witnessed greatly increased consumption rates, at 165,000 MT in 1955 and at 279,000 MT in 1970, the peak of such consumption. By 1981, the U.S. EPA estimate of lead consumed in combusted leaded gasoline was 61,000 MT and the figure in Table 3.3 for this same year was 111,000 MT. The dramatic declines in 1987 and 1989 reflected the mandated phasedown of lead in gasoline for the main U.S. vehicular fleet. 

The U.S. air lead levels are presented here for later periods as well. These later periods generally reflect decline in consumption of lead and consequently production of lead (U.S. EPA, 1986a, 2006). There was the major decline in leaded gasoline consumption due to regulatory restrictions leading to, first, a phasedown of the amounts of antiknock additive permitted in fuels in the 1980s and early 1990s, followed by an eventual phaseout. The numbers of point source lead emissions from primary and secondary lead smelters markedly declined as well. 

Roadway and other outside dust lead levels declined with the phasedown and phaseout of leaded gasoline but the rate of decline has been understandably slow given the long-term retention of deposited dusts in roadside soils... 

The agency elected not to pursue further technical analysis or RIA of the alternative OAQPS-recommended and CASAC-reviewed NAAQS. Instead, it elected to adopt a multimedia approach to regulating lead (U.S. EPA, 2006). The stated rationale for this decision lay in the observation that, formerly, leaded gasoline combustion was the dominant source of lead in ambient air and required control for air input reasons. The phasedown and the later-mandated phaseout of Pb in gasoline (1990 CAAAs) reduced the need to focus on mobile source-based air lead and amplified attention to inputs from other sources. 

Obviously, the gasoline supply picture is subject to constant change. The European Parliament has reportedly (10) "urged the Common Market Commission to postpone its plans for reducing the lead content in gasoline... ". In October, 1976, the U. S. EPA altered the lead phasedown schedule. 

The lead phasedown regulation and the increasing amount of unleaded gasoline have both caused substantial increases in the average aromatic content of the different grades of gasoline. 

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