Development of the releasable asbestos field sampler

Our plain-English summary of Development of the releasable asbestos field sampler, by J.R. Kominsky, J.W. Thornburg, G.M. Shaul, et al (Journal of the Air & Waste Management Association, 2010).

The study

• Authors: J.R. Kominsky, J.W. Thornburg, G.M. Shaul, W.M. Barrett, F.D. Hall, J.J. Konz
• Journal: Journal of the Air & Waste Management Association
• Published: 2010;60(3):294-301
• Cited by: 3 articles, as counted by NIH iCite
• Read it: PubMed · Publisher

Abstract

The releasable asbestos field sampler (RAFS) was developed as an alternative to activity-based sampling (ABS; personal breathing zone sampling during a simulated activity). The RAFS utilizes a raking motion to provide the energy that releases particulate material from the soil and aerosolizes the asbestos fibers. A gentle airflow laterally transports the generated aerosol inside of a tunnel to one end where filter sampling cassettes or real-time instruments are used to measure asbestos and particulate release. The RAFS was tested in a series of laboratory experiments to validate its performance and then was deployed for field trials in asbestos-contaminated soil at multiple geographical locations. Laboratory data showed the RAFS generated repeatable and representative aerosol particulate concentrations. Field tests showed the RAFS aerosolized asbestos concentrations were statistically correlated with total particle concentrations. Field tests also showed the RAFS aerosolized asbestos concentrations were statistically correlated with asbestos concentrations measured by multiple ABS tests with different activities, different soil/environmental conditions, and at different geographical locations. RAFS provides a direct measurement of asbestos emission from soil in situ without consideration of meteorology and personal activity on the asbestos transport to the breathing zone.

In plain English

The authors, working with and for the U.S. Environmental Protection Agency, described a new field instrument, the releasable asbestos field sampler (RAFS). It is meant as an alternative to activity-based sampling, in which air is sampled in a person's breathing zone during a simulated activity. The RAFS uses a motorized rake inside a small open-bottomed tunnel to disturb the top half inch of soil, and a fan carries the released dust to air filters. In laboratory tests on topsoil, soil moisture and fan speed significantly affected the dust produced, while rake speed was not a statistically significant factor. No measurable dust above background was released when soil moisture was 40% or greater. Field tests covered seven U.S. sites. At three sites, asbestos released by the RAFS was related to fine-dust levels. At four sites, RAFS asbestos levels were highly correlated with activity-based breathing-zone levels, though RAFS levels could be significantly higher. The authors concluded that the RAFS gives repeatable, representative data with less labor and cost. They named soil moisture above about 40% as its only apparent limitation.

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: Development of a soil-sampling instrument, with a laboratory and field performance evaluation
• Who was studied: Laboratory tests used generic topsoil. Field tests used soil at seven U.S. sites: Swift Creek, Clear Creek Management Area and Klamath Falls for the initial evaluation, and Coalinga, Sapphire, Vermont and Big Tex for side-by-side comparison with activity-based sampling.
• Exposure: Asbestos in soil. Swift Creek, Clear Creek, Coalinga, Vermont and Sapphire involved naturally occurring asbestos. Klamath Falls soil was contaminated with asbestos-containing building materials (cement board, floor tile, roofing paper, pipe insulation). Big Tex soil was contaminated with asbestos from a vermiculite exfoliation plant. The methods describe chrysotile with trace amphibole at most sites and amphibole asbestos at Sapphire. The results report chrysotile at most sites and chrysotile with some amosite at Klamath Falls.
• Main results:
  • In laboratory tests, aerosol concentrations at the tunnel outlet were greatest 1.5 inches above the soil surface and fell with height.
  • In laboratory tests, soil moisture content and fan speed influenced the aerosol produced.
  • In laboratory tests, rake power was not a statistically significant variable.
  • In laboratory tests, no measurable particle release above background occurred at soil moisture of 40% or greater.
  • At the seven field sites, average soil moisture ranged from 2.8 to 29.1%, with a maximum of 43.8%.
  • At three sites, RAFS asbestos concentrations were related to 1 to 5 micrometer particle concentrations. The strongest correlation (0.90) was at Swift Creek, which had the highest average soil asbestos concentration (0.82%) and the lowest average soil moisture (5.1%).
  • Average RAFS asbestos concentrations were highly correlated with personal breathing zone concentrations from multiple activity-based sampling tests.
  • RAFS asbestos concentrations could be significantly higher than activity-based sampling concentrations.
• The authors' conclusion: The authors concluded that the RAFS provides repeatable and representative asbestos aerosolization data from soil in place, with less labor and at lower cost than activity-based sampling.
• Limitations the authors state:
  • The instrument cannot generate an aerosol from soil with moisture content greater than about 40%.
  • Rake speed could only be tested over a limited range.
  • The aerodynamic particle sizer used in the laboratory tests is not a true particle counter and reports concentrations lower than the true values. The authors applied correction factors.

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• Natural mineral fibers: conducting inhalation toxicology studies-part B: development of a nose-only exposure system for repeat-exposure in vivo study of Libby amphibole aerosol — A. Wang, A. Gupta, et al. (2023)
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