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Study of air quality in Barnett Shale finds few health effects

A review of air quality in the Barnett Shale using data from the Texas Commission on Environmental Quality finds that emissions related to natural gas production are below levels that would pose health concerns.

The study, by Houston-based ToxStrategies, was funded by the Barnett Shale Energy Education Council, an industry group. It was published in the journal Science of the Total Environment.

The study looked at 4.6 million measurements of targeted chemical compounds captured by seven monitors at six sites in the area from 2000 to 2011. Those monitors, part of a TCEQ network, either automatically sample the air once an hour daily or collect one air sample for 24 hours every sixth day.

Most of the time, the monitors detected six volatile organic compounds that are particularly related to natural gas production: benzene, toluene, ethylbenzene, hexane and two forms of xylene, all of which are toxic. Benzene is a known carcinogen.

While those and other compounds were present, none were detected in concentrations high enough to be considered a short-term acute health threat, the study said. One other compound, 1,2-dibromoethane, was detected at an annual level considered to pose a long-term chronic health risk.

The study said 1,2-dibromoethane is used in aviation and auto-racing fuel. The two monitors where it was detected are at Denton Municipal Airport and immediately south of Meacham Airport in far north Fort Worth.

Ed Ireland, director of the Barnett Shale Energy Education Council, said it was the first large-scale evaluation based on measurements of ambient air. In an email, Ireland said investigators concluded “shale gas production activities have not resulted in community-wide exposures to chemicals at levels that would pose a health concern.”

Bruce Baizel, head of the Oil & Gas Accountability Project for Earthworks, an environmental group, noted that the study was industry-funded and used “general air quality data collected by someone else.”

Baizel said the study “is completely disconnected from reality — real people living near real oil and gas compressors or well sites breathe these emissions and suffer real health effects.”

Since the data were collected, the TCEQ monitoring system has been expanded to include 12 devices in the Barnett Shale that take hourly measurements and additional devices that take one-day samples.