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6C H A P T E R 4 With the elimination of lead from MOGAS, the relative contribution to total lead emissions from the remaining lead sources changed dramatically. The contribution of lead emissions from general aviation aircraft operating at airports where leaded AVGAS remains in use to total lead emissions in the United States can be evaluated through data available from the EPAâs National Emission Inventory (NEI) program. The NEI is a comprehensive and detailed estimate of air emissions of criteria pollutants, criteria pollutant precursors, and hazardous air pollutants. It is released by the EPA every 3 years based primarily upon data provided by state, local, and Tribal air agencies for sources in their jurisdictions and supplemented by data devel- oped by the EPA. Table 1 summarizes the lead emission inventory results by emissions based on the most recent NEI data available (calendar year 2011). Emissions from general aviation aircraft operating at airports are currently estimated to be the largest source of lead emissions in the United States. Changes in the relative contribution of general aviation aircraft operations operating at air- ports to U.S. lead emissions over time are presented in Table 2. Aircraft emissions increased from less than 1% of U.S. lead emissions in 1970 to 60% in 2011. This trend, combined with the revised assessment of the health impacts of lead that resulted in the 2008 revision of the NAAQS, has increased concerns related to aircraft lead emissions. Current Sources of Airborne Lead in the United States
Current Sources of Airborne Lead in the United States 7 Sector Lead Emissions Aircraft 486.08 Industrial Processes 224.87 Electric Generation 39.68 Industrial Boilers 32.99 Waste Disposal 10.71 Commercial/Institutional Fuel Combustion 6.39 Solvent Use 3.32 Residential Fuel Combustion 3.11 Locomotives 2.23 Commercial Marine Vessels 1.65 Bulk Gasoline Terminals 0.83 Miscellaneous Industrial (NEC) 0.71 Agricultural Field Burning 0.45 Gas Stations 0.37 Non-Road Diesel Equipment 0.01 Total 813.40 Aircraft Share 60% Source: U.S. EPA National Emission Inventory Program. www.epa.gov/ air-emissions-inventories/air-pollutant-emissions-trends-data Table 1. Total U.S. lead inventory for 2011 (tons/year). Sector 1970 1975 1980 1985 1990 1996 1998 2008 2011 Aircraft 0.6% 0.7% 1.2% 3.0% 12.4% 13.0% 12.7% 60% 60% Source: U.S. EPA 2015a. http://www.epa.gov/otaq/documents/aviation/420f15003.pdf Table 2. Airport lead contribution to total U.S. lead inventory (tons/year).
