A foul odor and blue haze is being reported in the Institute and St. Albans areas.
Metro 911 supervisor Toni Wallace says dispatchers received about seven calls about the odor Thursday morning.
Kanawha County Commission President Kent Carper says emergency responders are on standby.
State Department of Environmental Protection spokeswoman Kathy Cosco says DEP inspectors will drive through the area.
Earlier this year, dozens of Kanawha Valley residents reported a similar smelly haze. Federal and state environmental officials concluded that incident resulted from an unusually strong weather system trapping emissions from a power plant close to the Kanawha Valley.