Chemical analysis of World Trade Center fine particulate matter for use in toxicologic assessment

John K. McGee, Lung Chi Chen, Mitchell D. Cohen, Glen R. Chee, Colette M. Prophete, Najwa Haykal-Coates, Shirley J. Wasson, Teri L. Conner, Daniel L. Costa, Stephen H. Gavett

Research output: Contribution to journalArticlepeer-review

204 Scopus citations


The catastrophic destruction of the World Trade Center (WTC) on 11 September 2001 caused the release of high levels of airborne pollutants into the local environment. To assess the toxicity of fine particulate matter [particulate matter with a mass median aerodynamic diameter < 2.5 μm (PM2.5)], which may adversely affect the health of workers and residents in the area, we collected fallen dust samples on 12 and 13 September 2001 from sites within a half-mile of Ground Zero. Samples of WTC dust were sieved, aerosolized, and size-separated, and the PM2.5 fraction was isolated on filters. Here we report the chemical and physical properties of PM2.5 derived from these samples and compare them with PM2.5 fractions of three reference materials that range in toxicity from relatively inert to acutely toxic (Mt. St. Helens PM; Washington, DC, ambient air PM; and residual oil fly ash). X-ray diffraction of very coarse sieved WTC PM (< 53 μm) identified calcium sulfate (gypsum) and calcium carbonate (calcite) as major components. Scanning electron microscopy confirmed that calcium-sulfur and calcium-carbon particles were also present in the WTC PM2.5 fraction. Analysis of WTC PM2.5 using X-ray fluorescence, neutron activation analysis, and inductively coupled plasma spectrometry showed high levels of calcium (range, 22-33%) and sulfur (37-43% as sulfate) and much lower levels of transition metals and other elements. Aqueous extracts of WTC PM2.5 were basic (pH range, 8.9-10.0) and had no evidence of significant bacterial contamination. Levels of carbon were relatively low, suggesting that combustion-derived particles did not form a significant fraction of these samples recovered in the immediate aftermath of the destruction of the towers. Because gypsum and calcite are known to cause irritation of the mucus membranes of tile eyes and respiratory tract, inhalation of high doses of WTC PM2.5 could potentially cause toxic respiratory effects.

Original languageEnglish (US)
Pages (from-to)972-980
Number of pages9
JournalEnvironmental health perspectives
Issue number7
StatePublished - Jun 1 2003
Externally publishedYes


  • Carbon analysis
  • ICP-MS
  • Inhalation toxicology
  • Neutron activation analysis
  • Scanning electron microscopy
  • X-ray diffraction
  • X-ray fluorescence

ASJC Scopus subject areas

  • Public Health, Environmental and Occupational Health
  • Health, Toxicology and Mutagenesis


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