The explosion was the latest in a series of high-profile accidents this year up and down the Texas Gulf Coast, which is home to the highest concentration of oil refineries in the nation. In July, an explosion at an ExxonMobil refinery in Baytown left more than dozen people with minor injuries and put nearby residents under a shelter-in-place for three hours. 'Unacceptable trend' Toby Baker, the head of the Texas Commission on Environmental Quality, called it an "unacceptable trend of significant incidents" this week and said the petroleum industry must be accountable. But environmental groups for years have accused Baker's agency of being a toothless watchdog that provides inadequate oversight and slaps highly profitable corporations with only meager penalties. The TPC Group plant had been labeled a "high priority" violator by the U.S. Environmental Protection Agency following its last inspection in 2017 and had been cited multiple times in recent years for clean air violations.