The government and business leaders were more concerned about economic collapse then they were about long-term effects on health. The only people who should have been in that area were those equipped with Scott AirPak type oxygen systems. The idea that innocent people were tricked into returning with "safe" reports of air quality is disgusting.
My first visit to the area wasn't until the third week of October 2001 and there was still a distinct metallic flavor to the air that settled in the back of ones' throat if you didn't continually wear a mask. It forced people to drink absurd amounts of water to wash it away. God only knows what that was. Glad I endured the laughs of coworkers and kept that mask/respirator firmly affixed to my face.
~ Blue Jays ~
The "tip off" for a lot of people was when cars covered with dust were deemed condemned (or whatever the equiv. is for cars). A bunch of residents, parents of kids, etc. did get independent testing the second month and the toxins were off the charts in some locations.
In truth, nobody knows what really went into the "toxin soup" people were breathing or its long term effects.