Health officials in Contra Costa County are advising residents of Richmond, North Richmond, San Pablo and El Cerrito to "shelter-in-place" in the wake of Chevron Refinery fire in Richmond.
Residents are asked to go inside, turn off any air conditioning and close doors and windows as well as vents and fireplace flues.
Bay Area residents driving through the area are urged to roll up the windows of their cars since changing winds could bring the smoke to other parts of the region, affecting health.
"There's fine particles in smoke, and it can bypass the lungs and go into the circulatory system," said Lisa Fasano, a spokeperson for the Bay Area Air Quality Management District. "People who have asthma, emphysema and other lung conditions may find it very difficult to breathe."
The air district issued a "Level 3" warning for fire, meaning it can cause eye, skin, nose or respiratory irritation and that people with breathing problems should take extra caution.
Fasano said that six inspectors from the Bay Area Air Quality District were currently monitoring the air in Richmond and surrounding communities, with results expected Tuesday.
The plume from the fire was an estimated 3,000 to 4,000 feet above ground level, officials said late Monday, and so far nothing unusual has shown up on tests.
"The plume is still high above and not touching down into the community," said Trisha Asunción, a hazardous materials specialist with the county.
Equipment is monitoring for carbon monoxide, oxygen, flammable compounds and volatile organic compounds, she said.
The California Air Resources Board tracks the largest emitters of greenhouse gases in the state. Oil refineries, power plants and cement plants lead all industrial facilities statewide in pumping out carbon dioxide, a byproduct of burning fossil fuels that has been building up in the Earth's atmosphere in increasing concentrations.
The Chevron oil refinery in Richmond was the single largest California emitter in 2010, emitting 4.5 million metric tons of greenhouse gases. The Shell refinery in Martinez was second, with 4.4 million metric tons.
Staff writer Kristin J. Bender contributed to this report. Contact Dana Hull at 408-920-2706. Follow her at Twitter.com/danahull.