Refinery fire in California
A fire at one of the country's largest refineries spewed thick black smoke over cities in the San Francisco Bay area, sending scores of residents to hospitals.
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Chevron Richmond Refinery
Smoke and flame billow from a crude oil unit at the Chevron refinery in Richmond, Calif., Monday, Aug. 6, 2012.
Randy Sawyer, the chief environmental and hazardous materials officer for the county's health services agency, said any kind of smoke can be toxic, but added: "In this smoke, there can also be all kind of byproducts that can be toxic."
Credit: AP Photo/ContraCosta Times, D. Ross Cameron
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