Analysis released last month by the Environmental Defense Fund ( compared trends in air pollution data collected by the state with public records of oil and gas activity in the Barnett Shale and found a correlation between the ambient levels of common hydrocarbons and the amount of condensate produced by natural gas wells in Denton County, Texas.

A related analysis of state air pollution monitoring data between 2002 and 2008 found that the air in Denton county contained more non-methane hydrocarbons (including some potentially hazardous pollutants) than any of the other counties in the Dallas-Fort Worth area where the monitoring was conducted.

Hydrocarbons include many chemicals found in natural gas and petroleum. Most are considered volatile organic compounds (VOCs), which contribute to the formation of ground-level ozone or smog. Environmentalists are also concerned because methane, a main component in natural gas, contributes to greenhouse gas emissions and climate change.

“EDF is not opposed to shale drilling for natural gas, a valuable national resource and cleaner transition fuel,” said Ram—n Alvarez, Ph.D., senior scientist who led the analyses, in a prepared statement. “We simply want to see production done in the most environmentally responsible way possible. The good news is that many emissions controls can actually increase profits for natural gas producers.”

Proposed recommendations by the Environmental Defense Fund include expansion of VOC monitoring, especially in other Barnett Shale counties with significant condensate production (e.g., Wise, Hood, Parker); adoption of cost-effective oil and gas emissions controls, beginning with condensate tanks; and analyzing the effects of emissions in the Barnett Shale area on health and regional ozone levels.

To download the Environmental Defense Fund”s analysis cited in this article, click here. To download the related analysis, “Analysis of AutoGC and VOC Canister Data in the DFW Area,” click here.