Exxon Mobil Corp. has told residents of a neighborhood in Baytown, Texas, that process gas oil was released on Sunday in vapor from the company's 557,000 barrel per day refinery in Baytown, said Texas Commission on Environmental Quality spokesman Terry Clawson. Spokeswomen for Exxon did not reply to phone messages.
The oil covered yards, cars and homes near the refinery, 27 miles east of Houston.
Investigators were taking samples of the oil from vehicles and buildings along with soil samples, Clawson said.
"We're trying to flesh out what occurred there," Clawson said.
Exxon sent contractors through a public housing complex on Tuesday to clean oil off the sides of buildings, the Houston Chronicle reported on Wednesday.
Investigators also will determine if the oil contained elements harmful to human health, Clawson said. Initial indications were that short-term exposure to process gas oil would not be harmful.
Process gas oil is made from crude oil in a refinery's crude distillation unit and is sent to a catalytic cracking unit for refinement into gasoline.