Occupational exposures during the World Trade Center disaster response

Our plain-English summary of Occupational exposures during the World Trade Center disaster response, by K.M. Wallingford, E.M. Snyder (Toxicology and Industrial Health, 2001).

The study

• Authors: K.M. Wallingford, E.M. Snyder
• Journal: Toxicology and Industrial Health
• Published: 2001;17(5-10):247-53
• Cited by: 25 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Upon the request of the New York City Department of Health, the Centers for Disease Control and Prevention's National Institute for Occupational Safety and Health (NIOSH) monitored occupational exposures among emergency response workers during the rescue and recovery activities at the World Trade Center disaster site from September 18 through 4 October 2001. During this period, over 1,200 bulk and air samples were collected to estimate or characterize workers' occupational exposures. Samples were collected and analyzed for asbestos, carbon monoxide (CO), chlorodifluoromethane (Freon 22), diesel exhaust, hydrogen sulfide, inorganic acids, mercury and other metals, polynuclear aromatic hydrocarbons, respirable particulate not otherwise regulated (PNOR), respirable crystalline silica, total PNOR, and volatile organic compounds. Exposures to most of these potential hazards did not exceed NIOSH Recommended Exposure Limits or Occupational Safety and Health Administration Permissible Exposure Limits. However, one torch cutter was overexposed to cadmium and another worker (and possibly three others) was overexposed to CO. The elevated cadmium and CO levels were the result of workers using oxy-acetylene cutting torches and gasoline-powered cutting saws. Recommendations were made to ensure adequate ventilation and worker understanding when using these tools and, where possible, to substitute rechargeable, battery-powered cutting saws for gasoline-powered ones. Toxicology

In plain English

This NIOSH report described sampling of emergency response workers' exposures at the World Trade Center disaster site from September 18 through 4 October 2001. Over 1200 samples were collected, including 804 air samples for asbestos. The article did not name the asbestos fiber types. Of 29 settled dust samples, 26 (90%) had less than 1% asbestos and three had between 1% and 3%. Counting all fibers by phase contrast microscopy, 25 air samples exceeded the limit of 0.10 fibers per cubic centimeter. All 18 of these that were also checked by electron microscopy, which identifies asbestos, had asbestos below 0.10. Most non-asbestos fibers were fibrous glass, gypsum and cellulose. One torch cutter's cadmium level exceeded the OSHA limit. Carbon monoxide reached 242 ppm in a saw operator's sample, and two instant readings passed 1200 ppm. The authors concluded that sampling found no asbestos exposure above the limits, at least after September 18. They noted few bulk samples, seven high samples still awaiting electron microscopy, and no data on community exposures.

We wrote this plain-English summary from the full article with the help of AI, and a second AI model checked each sentence against the article. It is not the authors' wording; the abstract and the article are their own account.

What the study did and found

• Design: Industrial hygiene exposure assessment: bulk and air sampling (personal breathing zone and general area) at a disaster site
• Who was studied: Emergency response workers (search and rescue, construction, demolition and support services) at the World Trade Center disaster site, New York, September 18 through 4 October 2001. Over 1200 bulk and air samples were collected.
• Exposure: Asbestos (the authors give insulating and fireproofing materials as the source; fiber types not named), measured in 804 air samples and in bulk samples of settled debris and fireproofing. Also measured: carbon monoxide, cadmium and other metals, crystalline silica, PAHs, VOCs, inorganic acids, diesel exhaust, hydrogen sulfide, mercury, Freon 22 and particulate.
• Main results:
  • Of 29 bulk samples of undisturbed settled dust analyzed for asbestos, 26 (90%) had less than 1% asbestos by mass and the other three had between 1% and 3%.
  • Of three bulk samples of fireproofing material from steel beams, one had no detectable asbestos and two had less than 1%.
  • Phase contrast microscopy found fibers in 358 (45%) of the 804 asbestos air samples. Excluding 30-minute samples, 25 exceeded the NIOSH and OSHA limit of 0.10 fibers per cubic centimeter.
  • Of the 25 samples above 0.10 fibers per cubic centimeter by phase contrast microscopy, 18 were also analyzed by electron microscopy (TEM). All 18 had asbestos concentrations below 0.10 fibers per cubic centimeter (range 0.0022 to 0.063). The other seven had total fiber concentrations of 0.10 to 0.20 fibers per cubic centimeter and had not yet been analyzed by TEM.
  • Polarized light microscopy of those 25 air samples found that most non-asbestos fibers were fibrous glass, gypsum and cellulose.
  • In 96 air samples below 0.10 fibers per cubic centimeter by phase contrast microscopy that were also analyzed by TEM, all had asbestos below 0.10 (range not detected to 0.024). No asbestos fibers were detected in 56 of them.
  • None of the 30-minute asbestos samples exceeded the OSHA short-term limit of 1.0 fibers per cubic centimeter.
  • Carbon monoxide in 99 air samples ranged from 0.16 to 242 ppm. The highest, from a gasoline-powered cutting saw operator, exceeded the NIOSH ceiling limit of 200 ppm. Two instantaneous peaks (1239 and 1368 ppm), one from a torch cutter and one from a saw operator, exceeded the 1200 ppm level NIOSH considers immediately dangerous to life and health.
  • One air sample from an oxy-acetylene torch cutter had a cadmium concentration above the OSHA limit. The text prints the values as 8.6 mg/m3 against a limit of 5.0 mg/m3.
  • No respirable crystalline silica was detected in 18 air samples, although 26 of 27 bulk samples contained crystalline silica (median 3.2%).
  • The authors attributed the overexposures to one torch cutter (cadmium) and one worker, possibly three others (carbon monoxide), cutting steel.
• The authors' conclusion: The authors concluded that extensive air sampling found no occupational asbestos exposure (as determined by TEM) above the NIOSH or OSHA limits, at least after September 18. They judged that the seven unconfirmed samples most likely would also be below 0.10 fibers per cubic centimeter by TEM.
• Limitations the authors state:
  • Only a limited number of bulk samples were analyzed.
  • The seven samples above the limit by phase contrast microscopy had not yet been analyzed by TEM when the article was written.
  • The asbestos sampling gives no data on occupational exposures before the sampling period.
  • The sampling was designed to assess occupational exposures, not community exposures.
  • The direct-reading instruments for carbon monoxide and hydrogen sulfide were calibrated only before and after deployment, not before and after each use.

Topics

Medical terms in this study, explained in our Lexicon: Occupational Exposure, NIOSH, Crystalline, Permissible Exposure Limit (PEL).

Related studies

• Health and environmental consequences of the world trade center disaster — P.J. Landrigan, P.J. Lioy, et al. (2004)
• Development of an exposure assessment method for epidemiological studies of New York State personnel who responded to the World Trade Center disaster — M.L. Herdt-Losavio, M.P. Mauer, et al. (2008)
• Characterization of the dust/smoke aerosol that settled east of the World Trade Center (WTC) in lower Manhattan after the collapse of the WTC 11 September 2001 — P.J. Lioy, C.P. Weisel, et al. (2002)
• Acute eosinophilic pneumonia in a New York City firefighter exposed to World Trade Center dust — W.N. Rom, M. Weiden, et al. (2002)
• The legacy of World Trade Center dust — J.M. Samet, A.S. Geyh, et al. (2007)
• Assessing truck driver exposure at the World Trade Center disaster site: personal and area monitoring for particulate matter and volatile organic compounds during October 2001 and April 2002 — A.S. Geyh, S. Chillrud, et al. (2005)

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