A new study seems to clear the air about air quality around north Texas natural gas wells. The Barnett Shale Energy Education Council study says there are no harmful levels of benzene and other compounds around the sites. Executive Director Ed Ireland says this doesn’t mean there is no benzene in the air. He points out that it’s present in the air from car traffic. He defends the study from critics who point out it’s paid for by the industry. Ireland says they hired an outside engineering firm to do the study. Fort Worth and Southlake plan to do air quality studies on their own.