1. Environmental Protection Agency (EPA) (2010c). Pollutants in the ambient air. http://www.epa.gov/apti/course422/ap2.html . Accessed June 10, 2012.
2. Environmental Protection Agency (EPA) (2010d). Air pollution monitoring. http://www.epa.gov/oaqps001/montring.html . Accessed June 10, 2012.
3. Environmental Protection Agency (EPA) (2010e). Air quality trends. http://www.epa.gov/airtrends/2011/report/highlights.pdf . Accessed June 10, 2012.
4. Environ International Corporation (2011). “User’s Guide: Comprehensive air quality model with Extensions Version 5.40”, September.
5. Texas Commission on Environmental Quality (TCEQ) (2007). Dallas-Fort Worth attainment and reasonable further progress demonstrations for the 1997 eight-hour ozone standard, Project No. 2006-013-SIP-NR, 05/23/2007. http://tceq.state.tx.us/implementation/air/sip/dfw_revisions.html . Accessed 25 November, 2010.