A proposal by state leaders to double the number of permanent air monitors in North Texas — with the natural gas industry picking up the tab — drew mixed reactions locally.

While state regulators have not yet indicated where in the 24-county Barnett Shale region the next eight monitors would go, they have indicated that operators would pay the costs. Monitors cost about $250,000 apiece to install and run the first year, and $100,000 every year after that.

Two ambient air quality monitors went online in Dish and at Eagle Mountain Lake, in Tarrant County, in April in response to concerns about emissions from shale drilling and production. The Texas Commission on Environmental Quality announced in June that more permanent monitors would be installed in Decatur, Flower Mound and southeastern Tarrant County.

State Sen. Jane Nelson, R-Flower Mound, issued a press release Monday morning praising the move, later saying in an e-mail that it was appropriate that the industry “share in the costs of these monitors rather than place an additional burden on taxpayers.”

“My understanding is that the data will be analyzed by an independent third-party,” Nelson wrote.

For state Sen. Wendy Davis, D-Fort Worth, public perception could be a problem. Residents and environmental groups have questioned the completeness of the data coming from the current monitors.

The permanent monitors, which use automated gas chromatograph technology, measure 46 toxic compounds. Each AutoGC monitor measures the same compounds as other monitors around the state. While many of those compounds are also byproducts of natural gas drilling and production, regulators have said that other byproducts are not, including sulfur compounds and formaldehyde and other carbonyl compounds.

The town of Dish placed a 24-hour Summa canister near the AutoGC monitor at Clark Airport to compare readings in mid-June. Even though permanent air monitors continuously measure meteorological conditions along with the presence of toxic compounds, they are also taken offline for one to two hours each day for calibration, according to TCEQ records.

In testifying to the Environmental Protection Agency recently, Dish Mayor Calvin Tillman presented the monitor and canister measurements side by side, saying they were too disparate for residents to have confidence in the monitors.

Davis released a letter she sent to TCEQ on Monday detailing a number of steps needed to secure the public’s confidence in an expanded monitoring program.

Mindful of the role the industry plays in the state and regional economies, “the health and safety of the public must always be of equal concern,” Davis wrote.

PEGGY HEINKEL-WOLFE can be reached at 940-566-6881. Her e-mail address is pheinkel-wolfe@dentonrc.com .