Monitoring an asbestos spray process

Our plain-English summary of Monitoring an asbestos spray process, by J.W. Skidmore, J.S. Jones (The Annals of Occupational Hygiene, 1975).

The study

• Authors: J.W. Skidmore, J.S. Jones
• Journal: The Annals of Occupational Hygiene
• Published: 1975;18(2):151-6
• Cited by: 1 article, as counted by NIH iCite
• Read it: PubMed · Publisher
• In J-M's library: Johns-Manville's company medical library held a copy (J-M no. 004346).

In plain English

This study measured airborne asbestos fibres during an asbestos-cement spray job used to fire-proof the steel frame of a new maternity unit at the City Hospital, Nottingham. Amosite was the only asbestos type in the cement mix, which was dampened before spraying. Samples were taken on three days. In the spray operator's breathing zone, concentrations of fibres 5 to 100 micrometres long averaged 7.0 fibres/cm3, from 4.5 to 8.5 across days. Transferring dry amosite from the bag averaged 2.6 fibres/cm3. At 15 and 30 feet from the sprayer, averages were 0.03 and 0.01 fibres/cm3. Of 19 samples taken beyond the construction site, only a single amosite fibre was seen. After the spray team left, asbestos debris remained and was swept dry by a workman with no respiratory protection. A later test sweeping of 4 square yards produced over 2 fibres/cm3 in the sweeper's breathing zone. Samples taken after handover found no fibres. The authors concluded that the spraying posed no significant hazard to other workers who stayed clear of a screened spray area, but that the clean-up was inadequate.

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: Workplace air-monitoring (field measurement) study of one asbestos spray operation
• Who was studied: Asbestos spray work, by two-man spray teams, during construction of a maternity unit in the grounds of the City Hospital, Nottingham (England). Samples were taken on three separate occasions. No dates for the sampling are given.
• Exposure: A mixture of asbestos, cement and water, sprayed onto structural steel girders for fire-proofing. Amosite was the only asbestos type used. The dry mix was pre-damped with water in a revolving drum before spraying. Stages measured were bag-to-hod transfer, emptying into the pre-damping drum, loading the spray machine, and spraying, plus later dry sweeping of debris.
• Main results:
  • Spray operator's breathing zone, fibres 5 to 100 micrometres long (Table 3): 4.5, 8.5 and 7.5 fibres/cm3 on days 1 to 3, mean 7.0. Preparatory stages had means of 2.6 (transferring amosite from bag to hod), 1.2 (emptying hod into drum) and 0.8 (loading spray machine) fibres/cm3. The authors summarise these as about 1 to 8 fibres/cm3 near the operatives.
  • Mean concentrations were 0.03 fibres/cm3 at 15 ft from the sprayer and 0.01 at 30 ft. On the floor above and the floor below they were 0.02 and 0.01 fibres/cm3. Fibres reached those floors through holes in the structure.
  • Counting all fibres longer than 1 micrometre raised counts only marginally (Table 4: spraying mean 7.4 fibres/cm3).
  • Of 19 samples collected for 4 to 24 hours at points beyond the building site (including buildings 60 and 500 yd away), only one amosite fibre was seen.
  • Asbestos debris left on floors was swept up dry by a workman with no respiratory protection. A later test sweeping produced over 2 fibres/cm3 in the sweeper's breathing zone while clearing 4 square yards.
  • After completion and handover of the building, several 24-hour samples were taken in various parts of the building. No fibres were detected on any of them.
• The authors' conclusion: The authors concluded that, with adequate screening, the spraying posed no significant health hazard to other workers who stayed clear of the spray area. They found the hazard lay in inadequate clean-up afterwards, which left asbestos debris that was later swept dry. They stated that more attention to cleaning up could greatly reduce this risk.
• Limitations the authors state:
  • No samplers were on site when the workman was actually sweeping the debris. The sweeping concentration comes from a later test sweeping.
  • The fibre size range counted (5 to 100 micrometres) is the one considered appropriate for asbestosis risk. The authors note the fibre size involved in cancer was not known.

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• Inhalation and injection studies in rats using dust samples from chrysotile asbestos prepared by a wet dispersion process — J.M. Davis, J. Addison, et al. (1986)
• Some observations on the in vitro cytotoxicity of chrysotile prepared by the wet dispersion process — I.P. Gormley, R.E. Bolton, et al. (1983)
• 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)
• Exposure of UK industrial plumbers to asbestos, Part I: Monitoring of exposure using personal passive samplers — G. Burdett, D. Bard (2007)

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