It’s been more than two weeks since a freight train derailment in the U.S. state of Ohio caused a massive toxic chemical spill. The local authorities are trying to persuade fearful residents that the environment is now safe, even opening up a special clinic to carry out health tests.

The derailment has raised urgent questions about the safety of trains running several miles long, carrying harmful materials through some of the nation’s most populous areas. CGTN’s Owen Fairclough has more.