The closing of numerous chemical plants and refineries in Houston due to severe weather, heavy rain and flooding from Hurricane Harvey resulted in very high releases of toxic pollutants into the air. Public health experts have expressed concerns about the health implications for people of this increased industrial pollution and say the affects are already being noticed. Some experts have also expressed concern about the risk of water contamination from floodwaters and potential health impacts. [refers to Chevron Phillips, Equistar, ExxonMobil Shell, Valero Energy]