Katy Roemer, RN, remembers the fire that took place in 2012 at the Chevron oil refinery in Richmond, Calif., a 12-mile drive from the Kaiser Permanente Oakland Medical Center, where she works as a maternity nurse. The fire burned out of control for more than five hours, spewing a huge black cloud of toxic chemicals, including sulfur dioxide and nitrogen oxide, into the air. Bay Area residents were advised to stay inside, close windows and doors, turn off air conditioners and heating units, and have duck tape on hand in case it was needed to further seal the windows and doors. Pets and children were to be kept inside.