Physical characteristics and health effects of aerosols from collapsed buildings

Our plain-English summary of Physical characteristics and health effects of aerosols from collapsed buildings, by S.H. Gavett (Journal of Aerosol Medicine, 2006).

The study

• Author: S.H. Gavett
• Journal: Journal of Aerosol Medicine
• Published: 2006;19(1):84-91
• Type of article: Review
• Cited by: 5 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

Airborne pollutants can rise to extreme levels when large buildings fall down. The terrorist attack on New York's World Trade Center (WTC) towers caused the release of an enormous quantity of pulverized building materials and combustion products into the local environment. Particulate matter (PM) from crushed WTC building materials is primarily non-respirable (>96% larger than 10 microm mass median aerodynamic diameter [MMAD]) and composed of fibrous and nonfibrous components such as gypsum, calcite, silica, glass fibers, cellulose, and asbestos. Respirable fine WTC PM (PM(2.5)) may include finely crushed building materials as well as combustion products such as dioxins and polycyclic aromatic hydrocarbons (PAHs). Rescue workers at the WTC site had exposure-related increases in the incidences of nasal congestion, bronchial hyperreactivity to aerosolized methacholine, gastroesophageal reflux disease, and persistent cough. Toxicological studies in mice indicate that WTC PM(2.5) causes airflow obstruction above a critical dose. The review of physical characteristics and health effects of major pollutants derived from the collapse of the WTC towers has assisted in risk assessment efforts related to the collapse of large buildings.

In plain English

This article was a review of published research on the dust and smoke released when large buildings collapse. It focused on the 2001 collapse of New York's World Trade Center (WTC) towers. The review described studies finding that at least 96% by weight of settled dust samples near the site consisted of particles larger than 10 micrometers, which the author called non-respirable. Fibrous components of the dust included chrysotile asbestos, glass fibers and cellulose. In one set of 29 settled dust samples, 26 had less than 1% asbestos by weight and three had 1–3%. Airborne samples taken at least 7 days after the attack did not exceed the NIOSH limit of 0.1 asbestos fibers per cubic centimeter. Cited firefighter studies linked heavier exposure to airway hyperreactivity and to persistent 'WTC cough.' Cells from one highly exposed firefighter's lungs contained chrysotile and amosite asbestos fibers. Mouse studies suggested that fine WTC dust affected the airways only above a threshold dose. The author concluded that the WTC disaster can guide health risk assessments for future building collapses.

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: review of published studies
• Who was studied: Published studies of dust and air samples, rescue workers (mainly firefighters), residents, mice and cultured cells related to the September 2001 World Trade Center collapse in New York City, plus earlier work on the 1995 Hanshin earthquake in Japan
• Exposure: Dust from crushed building materials (concrete, wallboard, gypsum, calcite, silica, glass fibers, cellulose, chrysotile asbestos) and combustion products such as polycyclic aromatic hydrocarbons
• Main results:
  • In settled dust samples collected near the WTC site on 16 and 17 September 2001 (Lioy et al.), at least 96% by weight was particles larger than 10 micrometers
  • Of 29 WTC settled dust samples collected by NIOSH from 18 September to 4 October 2001, 26 had less than 1% asbestos by weight and the other three had 1–3%
  • None of the airborne samples collected at the same time (at least 7 days after 9/11) exceeded the NIOSH recommended exposure limit of 0.1 asbestos fibers per cubic centimeter of air
  • Chrysotile asbestos fibers were found in all samples collected indoors next to the WTC site on 19 November 2001, making up less than 1% of sample volume
  • Among firefighters one month after 9/11, 8% of the moderately exposed sample (2/25) and 25% of the highly exposed sample (19/77) were hyperreactive to methacholine
  • In a medical monitoring program of 10,116 WTC firefighters, 8% of highly exposed, 3% of moderately exposed and no non-exposed firefighters had WTC cough in the first 6 months after 9/11
  • In one highly exposed firefighter with eosinophilic pneumonitis, lung lavage macrophages contained fibers including chrysotile and amosite asbestos
  • In mice, the highest dose of WTC PM2.5 tested caused significant airflow obstruction in response to methacholine; lower doses did not cause significant inflammation or airflow obstruction
• The authors' conclusion: The author concluded that health effects of collapsed-building aerosols depend on their source, characteristics and concentrations. Mouse studies indicate that effects of WTC PM2.5 may occur only above a threshold dose. The WTC disaster can serve to guide future collapsed-building health risk assessments.
• Limitations the authors state:
  • The author noted that settled dust may not accurately represent the proportions of airborne fine and coarse particles after a collapse
  • The author noted that a cited general-population survey on asthma severity had several limitations in study design

Topics

Medical terms in this study, explained in our Lexicon: Obstructive Lung Disease.

Related studies

• The legacy of World Trade Center dust — J.M. Samet, A.S. Geyh, et al. (2007)
• 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)
• Health consequences of the September 11 World Trade Center attacks: a review — J. Moline, R. Herbert, et al. (2006)
• Emission of airborne fibers from mechanically impacted asbestos-cement sheets and concentration of fibrous aerosol in the home environment in Upper Silesia, Poland — J.S. Pastuszka (2009)
• Thoracic fraction of inhaled fiber aerosol — Y.S. Cheng, W.C. Su (2013)
• 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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