I remember a few stories about doctored memos on that air quality testing. They are posted here at FR, someplace.
Mercury
OSHA has taken 242 air samples for inorganic mercury. No mercury was detected. Also, 36 bulk samples previously collected from rubble were re-analyzed for mercury and none was detected. Additionally, 10 bulks were taken on 1/3, with one sample detecting mercury at 0.9ppm and nine samples did not contain mercury. 38 bulk samples were taken between 1/8 and 1/11/02; results indicate 0.1 to 0.2 ppm mostly in around the footprint of Bldg.-6, and in the pit between WTC tower 1&2. 10 bulks taken on 6/5, inside 130 Cedar, detected mercury from 0.3 to 0.5 ppm. One bulk taken in 130 Cedar on the 8th floor in the lab area (off floor below lab table) detected 10.0 ppm mercury.