Energy In Depth, a public outreach branch of the Independent Petroleum Association of America, took a shot on Tuesday at a new study on hydraulic fracturing's air emissions.

The new study, released Monday by the Colorado School of Public Health, concluded those living within half a mile of a hydraulically fractured well have an increased risk of contracting illnesses because of volatile organic compounds (VOCs) that get released in the air.

But Energy In Depth criticized the new study, saying it assumed too much about area residents' behavior, and uses data gathered at a time before Colorado enacted stricter air standards.

This study is bad guesswork. You can't make credible predictions about the future when you rely on flawed assumptions about what's happening today, said Simon Lomax, Energy in Depth's Research Director.

Hydraulic fracturing is a drilling technique in which natural gas is extracted from fissures underground caused by the injection of thousands of gallons of water sand and chemicals.

When a well is completed and set to production, the study said toxic VOCs are emitted. People living within half a mile, the study found, are susceptible to reversible cellular changes according to the Environmental Protection Agency's non-cancer hazard index.

More Study Needed

These preliminary results indicate that health effects resulting from air emissions during unconventional [Natural Gas Development] warrant further study. Prospective studies should focus on health effects associated with air pollution, read the report.

But Lomax said the report took too much for granted for its results to be credible, including the assumption that the residents of Battlement Mesa, in Garfield County where the study was conducted, would never leave the town itself and be exposed to 24-hour doses of VOCs.

Lomax said the study purposefully avoided VOCs emitted by a local highway in determining where to test and where not to -- and thus disregarded naturally occurring VOCs from vehicle traffic in their report.

Most damaging, Lomax said, is how the report itself leaves room for error, in that topography and meteorology each determine how a person is exposed to the toxic compounds; people living near a well may in fact not be at greater risk after all.

The School's report, did find that natural gas wells emit carcinogenic compounds like benzene, and the American Lung Association said Monday that VOCs were linked to levels of ozone in Wyoming typically expected in large metropolitan areas.

Garfield County health official Jim Rada said air quality falls within EPA standards and that nothing so far suggests the local population is at an increased risk of cancer.

Hydraulic fracturing has been under considerable scrutiny in recent years because it helped fuel an energy bonanza in certain parts of the Rockies, Texas, and the East, including Ohio and parts of Virginia.

The EPA's reviewing water quality tests in Pavillion, Wy., and Dimock, Pa., where local residents are convinced the drilling technique by Encana Corp.(NYSE: ECA) and Cabot Oil & Gas (NYSE: COG) contaminated groundwater supplies.

The EPA is also conducting its own study to determine if the drilling practice is safe for ground water.

These data show that it is important to include air pollution in the national dialogue on unconventional Natural Gas Development that, to date, has largely focused on water exposures to hydraulic fracturing chemicals, the report said.