170,000 Pages Just Released... What Did NYC Know After 9/11?

Twenty-five years after the September 11 attacks, New York City has released approximately 170,000 pages of records concerning toxic exposure, air quality and the government's response after the World Trade Center collapsed. The documents include records from 68 boxes that the city previously failed to locate, environmental testing from contaminated buildings and the so-called Harding Memo, showing that officials were already considering potential health-related legal claims within weeks of 9/11.

The records do not prove a deliberate cover-up. But they revive a disturbing question: what did officials know about the toxic dust, and when did they know it? From asbestos and...