Get the Lead Out

Mapping Background and Methodology

• Printable Map A: Sources of Airborne Lead Emissions in the United States[PDF 2MB]
• Printable Map B: Total Airborne Lead Emissions by United States County[PDF 2MB]
• Google map: Zoomable (localized) map of sources of airborne lead emissions

The most recent U.S. EPA inventory (2002) lists 16,600 facilities that emit lead into the nation's air. About 7,000 of these are relatively small, reported to release less than one pound of lead per year, and are not included in this map series. The remaining 9,600 facilities release significant amounts of lead each year, from one pound to more than 10,000 pounds -- the largest being 117,392 pounds from a lead smelter in Missouri. These lead polluters are spread throughout the United States (see map A) and located in many communities (see Google map).

In addition to individual polluters, lead can still be found in some types of aviation fuel and is a problem near airports. According to the EPA's inventory, airborne lead emissions can be found in every U.S. county. In some counties more than 10,000 pounds of lead are emitted into the air each year. The EPA monitoring stations responsible for testing for lead in the air (marked with stars on the maps) are not located throughout the country and are totally absent from some areas where lead emissions may be the highest.

Data on stationary and mobile sources of airborne lead were acquired from the U.S. EPA 2002 NEI version 3.0, including facility names, Standard Industrial Classification (SIC) code, address, county latitude, longitude and quantity of emissions. Lead emissions from airports were also included in the maps of stationary sources. In the past, airports were not included in EPA's tally of over 13,000 facilities that emit lead into the air, but consultation with EPA staff reveals that airports will be included in the list of facilities in the future, bringing the count to over 16,000 facilities.

Consultation with EPA staff also revealed variation between states on the extent and scope of inclusion of stationary sources in the inventory. To adjust for these inconsistencies only sources reported to emit greater than one pound of lead in 2002 were included in the stationary source maps (Map A and the Google map) and industry types that were not reported consistently across all states were excluded. These industry types were determined by comparing the representation of different industry types according to Standard Industrial Classification (SIC code) across the states. As a result of this analysis, the following industry types (SIC codes) were not represented in the stationary maps: schools below the university level (8211), churches (8661) and supermarkets (5411).

In addition, due to incomplete geographic data in the inventory, approximately 5 percent of sources were excluded from the Google map and 2 percent from the national map. County level totals were calculated based on the sum of all reported point, nonpoint and mobile emission tallies for each county. Air monitoring stations reported to monitor for lead and to be active as of December 31, 2007 were downloaded from the EPA Office of Air and Radiation Air Quality System Database on January 25, 2008. The maps were generated using ArcGIS software and Google Maps API to embed the maps into the NRDC web page.