* Board releases photo of vapor cloud prior to Aug 6 blaze
* Chevron says cloud may have been from fire fighting
HOUSTON (Reuters) - The head of the U.S. Chemical Safety Board called an August 6 fire at Chevron Corp's San Francisco Bay area refinery in Richmond, California, a "close call" for the surrounding community, according to a local media report on Monday.
"We are extremely pleased that there hasn't been any loss of life here, but still, I think that it behooves us to really look at this as a close call and that we need to look and try to prevent things that could have been starting early with a bigger impact to the community than we saw in this particular fire," said CSB Chairman Rafael Moure-Eraso, according to KGO-TV.
Moure-Eraso's comments came after the board, which is probing the cause of the fire along with state and federal regulators, released photos of a large vapor cloud rising from the refinery before a cloud of black smoke from burning hydrocarbon could be seen.
The CSB has said the vapor cloud enveloped about 20 workers at the refinery before the fire erupted on the 245,000 barrel per day refinery's sole crude distillation unit.
Chevron, in a statement issued following the CSB news conference, said the vapor cloud may not have led to the blaze, but been a by-product of fire-fighting efforts.
"It is premature to comment on the composition of the white cloud," Chevron spokeswoman Melissa Ritchie said in a statement.
"We do know that a significant amount of water was being applied on scene and that considerable steam was created," Ritchie said. "The black smoke that you see was a result of hydrocarbons that ignited. Because the white cloud did not ignite, we have questions about its composition."
In March 2005, the ignition of a hydrocarbon vapor cloud at BP Plc's Texas City, Texas, refinery killed 15 workers and injured 180 people.
The Chevron fire has lifted California gasoline prices on fears of shortages in West Coast refined products markets due to the shut crude unit, which does the initial refining of oil in the refinery and provides feedstock for all other units.
Chevron has said the refinery continues to produce transportation fuels at reduced levels using intermediate feedstocks to supply fuel-producing units.
Thousands of people in the surrounding community reported eye and throat irritation as a huge black cloud from the fire spread over the area. Several lawsuits have been filed against Chevron.
The Chemical Safety Board investigates chemical fires and explosions and makes recommendations to prevents further accidents. The board has no regulatory or enforcement authority.
(Reporting by Erwin Seba; Editing by Richard Borsuk)