The Texas Commission on Environmental Quality (TCEQ) operates seven continuous air monitors in the Barnett Shale area in North Texas. TCEQ Chairman Bryan Shaw, Ph.D., has said in the past that the number of continuous air monitors, or automatic gas chromatographs, makes the Barnett Shale air the most monitored air in the country. The devices, which are about the size of a small travel trailer and are permanently installed, take air samples every hour for 23 hours a day – except between 11 p.m. and midnight when the machines are recalibrated. They test for over 40 volatile organic compounds, or VOCs, and post the results on the TCEQ website. There are other air monitors in North Texas that monitor ozone.

In 2000, the first VOC monitor was installed on Hinton Street near Love Field in Dallas. The monitor at Fort Worth Meacham Field was installed in 2002. Since then, five additional monitors have been installed one in the town of Dish, one near Eagle Mountain Lake, and the others in Flower Mound, Decatur and Everman. The locations of these monitors were chosen so the monitors were near producing natural gas fields and facilities in the Barnett Shale.

Together, these air monitors have collected well over 100,000 air samples. From all of these, not a single sample has ever been anywhere near a level that TCEQ would consider a potential health issue. In fact, the sampled levels are considered to be “background” levels, that is, levels that are considered to be present most everywhere.

The graph below, from the TCEQ, shows the chemical compound benzene’s measurements taken over time by the continuous air monitors in the Barnett Shale. 

The measured levels, currently in the .1 to .2 parts per billion (ppb), are considered to be background levels. On any one day, a reading in this range would be considered high if it exceeded 180 ppb. The measured levels are 1,000 times lower. In other words, thousands of samples of air near Barnett Shale natural gas facilities show that these facilities do not contribute dangerous levels of VOC to the air.