With Houston’s rise to the status of most smoggy U.S. city, Texas Gov. George W. Bush, top contender for the GOP presidential nomination, is beginning to face criticism for his approach to environmental problems. Texas had serious air quality problems before Bush became governor in 1995, but some evidence indicates that the state’s air may now be even worse. The EPA is threatening to cut off hundreds of million of dollars in highway funds to Dallas and Fort Worth because of air quality problems, and local officials, many of them Republicans, claim that Bush’s appointees to the Texas Natural Resource Conservation Commission have failed to help them tackle the problem. Enviros and federal regulators say that the Bush administration has lightened the regulatory burden on the dirtiest Texas companies.