Farhad Goudarzi, director of public relation department of Tehran Air Quality Control Company announced that industries account for 3-4 percent of air pollution in the capital. He said Tehran refinery was the biggest pollution industrial unit in the vicinity of Tehran. "Industrial units mainly use mazut as fuel and this is a source of major pollution for areas around them," he noted. The official said power plants were the second polluting entities after refineries, singling out Be'that power plant in southern Tehran as a major pollution source.