1. U.S. Environmental Protection Agency (EPA).2002 National-Scale Air Toxics Assessment,http://www.epa.gov/ttn/atw/nata2002/(accessed September 5, 2009).
2. U.S. Environmental Protection Agency (EPA).2008 Toxics Release Inventory,http://www.epa.gov/TRI/index.htm(accessed July2, 2010).
3. Texas Commission on Environmental Quality (TCEQ). Personal communication with Air Quality Division Staff, October 2009.
4. U.S. Environmental Protection Agency (EPA). 2002 National Emissions Inventory (NEI)http://www.epa.gov/oar/data/reports.html(accessed September 5, 2009).