HOUSTON (ICIS)--Several US chemical plants and refineries are shutting down as a precautionary measure before Hurricane Ida hits Louisiana on Sunday. BASF is idling its Geismar, North Geismar and Vidalia sites by noon on Sunday, it said on Saturday. The Geismar site produces butanediol (BDO), ethylene oxide (EO), isocyanates, polyols and other chemicals. Shell began shutting down its Geismar and Norco facilities on Friday. The Norco site has a refinery, cracker and butadiene (BD) extraction unit.