NYC-WTC_000233986

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 28, 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 on or in the vicinity of the debris pile to characterize potential exposures. Below are the interim sampling results for Friday, September 28, 2001.

Air Samples

Acid Gases • 5 personal and 5 area air samples were collected for acid gases o Trace amounts of acid gases were detected on all area and most personal air samples (1 personal air sample had a sulfuric acid concentration of 0.5 mg/m^)

Asbestos • 99 personal air samples were collected by NYDOH contractors o Most personal sample 8-hour time-weighted average concentrations were below 0.042 fibers/cc as determined by PCM (3 were < 0.20 fibers/cc) o All short-term exposure limit samples were below 0.05 fibers/cc as determined by PCM

Carbon Monoxide • 22 real-time personal breathing zone samples were collected for carbon monoxide o All 8-hour time-weighted average concentrations were below 12 ppm o A single peak of 273 ppm was observed on an iron worker on the debris pile

K.M. Wallingford 10/15/01

CITY_21MC100_003245373

NYC-WTC_000233986