A health advisory issued because of flaring at the Shell refinery in Martinez this afternoon has been canceled.
A problem occurred at the refinery at about 12:40 p.m., said Randy Sawyer, the agency's chief environmental health and hazardous materials officer.
Sawyer said a vessel at the refinery somehow became "overpressurized," which activated a safety mechanism that releases pressure through flaring.
The flaring created puffs of black smoke rising up from the refinery. The smoke contained sulfur dioxide and combustible products, Sawyer said.
He said the smoke contains sulfur dioxide and other combustible products.
There were also reports of a strange odor in the area.
The flaring is considered a "Level 2" incident, meaning residents with respiratory problems or other health conditions are being advised to stay indoors, but there is no mandatory shelter-in-place warning.
No community warning sirens are being activated and no automated phone calls are going out, he said.
The health advisory was issued at 1:31 p.m. Sawyer said Contra Costa Health Services didn't issue the advisory right away because the situation was still being assessed.
"If they could stop it right away, we wouldn't have called a Level 2," he said.
The flaring stopped about 2:45 p.m. and the health advisory was lifted, Contra Costa Health Services spokeswoman Maria Duazo said.
The agency downgraded the incident from "Level 2" to "Level 0," meaning that everything has been controlled by refinery personnel, with no threat to the public, Duazo said.
The flaring has stopped and there is no expectation of any more odors coming from the refinery, Duazo said.
Last week's massive fire at the Chevron refinery in Richmond was considered a "Level 3," incident -- the highest level in the agency's system.