Texas has also sued BP over the release, which occurred as the British oil giant was battling the catastrophic Gulf of Mexico spill. The Environmental Protection Agency is also investigating.
The Galveston Daily News reports that residents say they became ill from the release. BP maintains the emissions didn't harm anyone.
Texas says BP emitted 500,000 pounds of chemicals, including carbon monoxide and benzene, during April and May in 2010.
BP issued the following response:
"Neither the Community Air Monitoring Network nor the BP fence-line monitors showed elevated readings during April and May 2010, and we do not believe that any negative health impacts resulted from flaring at BP's Texas City Refinery during this period. BP is defending and will continue to defend the lawsuits brought against it concerning this matter."
BP recently reached a $50 million settlement with the EPA over the 2005 explosion that killed 15 people at the Texas City refinery.