The company 's role in environmental pollution has been in the spotlight ever since the 1989 Exxon Valdez accident in Alaska , the worst oil spill in U.S. history . Shell says company had not sufficiently reduced sulfur emissions at four facilities . The facilities in question are in Texas , Louisiana and California . Exxon Mobil says they now meet federal standards on sulfur emissions .
Shell says company had not sufficiently reduced sulfur emissions at four facilities . The facilities in question are in Texas , Louisiana and California . Exxon Mobil says they now meet federal standards on sulfur emissions .