Desc: 9/11's Unsettled Dust: Directed by Lisa Katzman. The deadliest attack on American soil, 9/11 permanently altered the course of American life, history, politics, and world events. Yet, 9/11's significance as the worst manmade environmental disaster to impact a densely populated American city is largely hidden from public memory. 9/11's Unsettled Dust exposes how and why September 11 became the fulcrum for a human health tragedy that continues to unfold.