NYC-WTC_000234674

NYC 9/11 Public Portal Document

Centers for Disease Control and Prevention National Institute for Occupational Safety and Health Interim Air Sampling Report Friday, September 21,2001

Investigators from the National Institute for Occupational Safety and Health (NIOSH) collected air samples in areas immediately adjacent to the debris pile and on personnel actively involved in rescue efforts in the vicinity of the debris pile to characterize potential exposures. Below are the interim sampling results for Friday, September 21, 2001.

Air Samples

Asbestos • 45 personal and 6 area air samples were collected by NYDOH contractors o Personal sample 8-hour time-weighted average concentrations were below 0.04 fibers/cc as determined by PCM o All area sample results were below 0.01 fibers/cc as determined by PCM

Total Dust • 15 personal air samples were collected for total dust o Personal sample 8-hour time-weighted average concentrations were below 1.0 mg/nF

Melcds • 7 personal and 4 area air samples were collected for metals o Nothing of concern was found regarding metal analysis

Crystalline silica • 2 personal air samples were collected for crystalline silica o No crystalline silica was detected on any of the air samples

Carbon Monoxide • 5 real-time personal breathing zone samples were collected for carbon monoxide o Most 8-hour time-weighted average concentrations were below 2 ppm (one was 32 ppm) o A single peak of 823 ppm was observed on a torch cutter

CITY_21MC100_003280808

NYC-WTC_000234674