HOUSTON—A federal judge in Houston knocked $5.7 million off the fine Exxon Mobil faces for pollution from its largest U.S. crude oil refinery, according to court documents. U.S. District Judge David Hittner issued the ruling on Tuesday afternoon, imposing a $14.25 million penalty on Exxon for pollution from the Baytown, Texas, refinery and chemical plant complex over eight years. In 2017, Hittner issued a $19.95 million penalty to Exxon, finding it was responsible for the pollution from the Baytown complex between 2005 and 2013 as alleged in a lawsuit initially filed in 2010 under the U.S. Clean Air Act by the Sierra Club and Environment Texas. In July, the 5th U.S. Circuit Court of Appeals in New Orleans threw out the penalty and ordered Hittner to determine which violations of the Clean Air Act specifically caused harm to members of the organizations living near Exxon’s Baytown operations. The new penalty …