The facilities are located in every state, and are threatened by floods, hurricanes and wildfires that can cause dangerous leaks and explosions, according to a federal watchdog.
Hurricane Harvey was a wake-up call for petrochemical plants along the Gulf Coast to rethink plans for major floods. Some companies are starting to prepare for storms that are larger and more severe.
Neighborhoods around a Louisiana chemical plant have the highest cancer risk in the U.S. Residents felt powerless, until the Environmental Protection Agency released data on what they were breathing.