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

Our plain-English summary of 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, by P.J. Lioy, C.P. Weisel, J.R. Millette, et al (Environmental Health Perspectives, 2002).

The study

• Authors: P.J. Lioy, C.P. Weisel, J.R. Millette, S. Eisenreich, D. Vallero, J. Offenberg, B. Buckley, B. Turpin, M. Zhong, M.D. Cohen, C. Prophete, I. Yang, R. Stiles, G. Chee, W. Johnson, R. Porcja, S. Alimokhtari, R.C. Hale, C. Weschler, L.C. Chen
• Journal: Environmental Health Perspectives
• Published: 2002;110(7):703-14
• Cited by: 366 articles, as counted by NIH iCite
• Read it: PubMed · Publisher · Free full text

Abstract

The explosion and collapse of the World Trade Center (WTC) was a catastrophic event that produced an aerosol plume impacting many workers, residents, and commuters during the first few days after 11 September 2001. Three bulk samples of the total settled dust and smoke were collected at weather-protected locations east of the WTC on 16 and 17 September 2001; these samples are representative of the generated material that settled immediately after the explosion and fire and the concurrent collapse of the two structures. We analyzed each sample, not differentiated by particle size, for inorganic and organic composition. In the inorganic analyses, we identified metals, radionuclides, ionic species, asbestos, and inorganic species. In the organic analyses, we identified polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls, polychlorinated dibenzodioxins, polychlorinated dibenzofurans, pesticides, phthalate esters, brominated diphenyl ethers, and other hydrocarbons. Each sample had a basic pH. Asbestos levels ranged from 0.8% to 3.0% of the mass, the PAHs were > 0.1% of the mass, and lead ranged from 101 to 625 microg/g. The content and distribution of material was indicative of a complex mixture of building debris and combustion products in the resulting plume. These three samples were composed primarily of construction materials, soot, paint (leaded and unleaded), and glass fibers (mineral wool and fiberglass). Levels of hydrocarbons indicated unburned or partially burned jet fuel, plastic, cellulose, and other materials that were ignited by the fire. In morphologic analyses we found that a majority of the mass was fibrous and composed of many types of fibers (e.g., mineral wool, fiberglass, asbestos, wood, paper, and cotton). The particles were separated into size classifications by gravimetric and aerodynamic methods. Material < 2.5 microm in aerodynamic diameter was 0.88-1.98% of the total mass. The largest mass concentrations were > 53 microm in diameter. The results obtained from these samples can be used to understand the contact and types of exposures to this unprecedented complex mixture experienced by the surviving residents, commuters, and rescue workers directly affected by the plume from 11 to 12 September and the evaluations of any acute or long-term health effects from resuspendable dust and smoke to the residents, commuters, and local workers, as well as from the materials released after 11 September until the fires were extinguished. Further, these results support the need to have the interior of residences, buildings, and their respective HVAC systems professionally cleaned to reduce long-term residential risks before rehabitation.

In plain English

The authors analyzed three bulk samples of dust and smoke that settled east of the World Trade Center after its collapse on 11 September 2001. Two were collected on 16 September and one on 17 September 2001. One came from protected ledges on Cortlandt Street, one block east of the site. The other two came from the tops of cars on Cherry and Market Streets, about 0.7 km away. Most of the mass was pulverized building material, including cement, cellulose and glass fibers. Chrysotile asbestos made up 0.8% of the Cortlandt and Cherry Street samples and 3.0% of the Market Street sample by mass. Microscopy, however, estimated chrysotile at under 1% by volume in each sample. Most of the mass was in particles larger than 53 micrometers. The samples were alkaline. Polycyclic aromatic hydrocarbons (PAHs), which are combustion products, exceeded 0.1% of the mass. Dioxins were detectable but not excessive. The authors concluded that the toxicants with significant concentrations or potential surface loadings included asbestos, glass fibers, lead and PAHs.

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: Laboratory characterization (microscopic, chemical, radiological and particle-size analyses) of three bulk environmental dust samples; no people were studied
• Who was studied: Three samples of settled WTC dust and smoke from lower Manhattan, collected 16 and 17 September 2001. One came from protected ledges on Cortlandt Street, one block east of the WTC. Two came from the tops of automobiles on Cherry Street and Market Street, about 0.7 km from the site.
• Exposure: Settled dust and smoke from the WTC collapse and fires. It contained chrysotile asbestos, glass fibers (mineral wool and fiberglass), metals including lead, PAHs, PCBs, dioxins and furans, phthalate esters, brominated flame retardants and jet-fuel hydrocarbons.
• Main results:
  • By mass, the Cortlandt and Cherry Street samples each contained about 0.8% asbestos (chrysotile in Table 1). The Market Street sample contained 3.0%.
  • In the microscopic analysis, chrysotile made up less than 1% of each sample by volume, including the Market Street sample. Much of the chrysotile was attached to carbonate binder.
  • Most of the mass in all three samples was pulverized building and construction material, including cement, cellulose and glass fibers. Table 1 gives glass fiber as 40.0% in each sample.
  • Particle size: the largest share of the mass was in particles over 53 micrometers. These made up 61.50% (Cortlandt), 52.21% (Cherry) and 63.60% (Market). Particles under 2.5 micrometers made up 1.12% (Cortlandt), 0.88% (Cherry) and 1.30% (Market), per Table 1.
  • All samples were alkaline: pH 11.5 at Cortlandt Street, 9.2 at Cherry Street and 9.3 at Market Street (Table 1).
  • Lead measured 142,400 ng/g (Cortlandt), 483,500 ng/g (Cherry) and 289,200 ng/g (Market), dry weight (Table 2).
  • Total PAHs in the settled dust and smoke exceeded 0.1% of the mass.
  • PCBs, dioxins and furans were found at detectable but not excessive levels.
  • Alpha radioactivity was at background levels in all three samples.
• The authors' conclusion: The authors concluded that the toxicants with significant concentrations or potential surface loadings in the dust included asbestos, glass fibers, lead and PAHs.
• Limitations the authors state:
  • Only 1,000 particles per sample were analyzed microscopically. The authors stated this would prevent consistent detection of materials making up less than 0.1% of a sample.
  • The two cars sampled may have been moved from an adjacent road (FDR Drive) after 11 September.
  • The dark color of the samples may have caused slight underreporting of beta radioactivity.

Topics

Medical terms in this study, explained in our Lexicon: Settled Dust.

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• Summary of the development of a signature for detection of residual dust from collapse of the World Trade Center buildings — H.A. Lowers, G.P. Meeker, et al. (2009)
• Health effects of World Trade Center (WTC) Dust: An unprecedented disaster's inadequate risk management — M. Lippmann, M.D. Cohen, et al. (2015)
• The legacy of World Trade Center dust — J.M. Samet, A.S. Geyh, et al. (2007)

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