However, Neil Carman, a chemist and chief author of the environmental group's report, said progress is slow or nonexistent. And it said that voluntary cutback pledges by 36 grandfathered companies, praised by Gov. George W. Bush, solve only 2 percent of the problem. The Texas Natural Resource Conservation Commission agrees that grandfathered emissions are a big concern, spokesman Patrick Crimmins said. Voluntary cutbacks haven't solved the problem yet, officials acknowledge, but they said more companies are signing up. Top industries are aluminum smelters, electric power plants, oil refineries, and carbon-black plants.
Carbon black is a coal-like material used to make other products.
The biggest grandfathered pollutant is nitrogen oxide, a key ingredient of smog.