Airborne asbestos concentrations in buildings

Our plain-English summary of Airborne asbestos concentrations in buildings, by G.J. Burdett, S.A. Jaffrey (The Annals of Occupational Hygiene, 1986).

The study

• Authors: G.J. Burdett, S.A. Jaffrey
• Journal: The Annals of Occupational Hygiene
• Published: 1986;30(2):185-99
• Cited by: 23 articles, 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. 004310).

Abstract

Airborne concentrations of asbestos and other fibres were measured in 39 buildings containing asbestos materials used in their construction or present in warm-air heating systems and in four buildings without asbestos materials. Samples were collected onto membrane filters and analysed using both phase contrast optical microscopy (PCM) and transmission electron microscopy (TEM). Of the 235 samples analysed by PCM, 13% gave fibre concentrations above 0.01 fibres per millilitre (f ml-1); no sample exceeded 0.075 f ml-1. However, subsequent TEM analysis showed that most of the fibres were not asbestos and at only one site did the >5 µm long fibre concentration exceed 0.001 asbestos f ml-1. All sizes of asbestos fibres were also analysed in the TEM at x 17 000 magnification. Only 20% of the buildings had asbestos fibre concentrations above the limit of quantification (>4 fibres counted) and often only a few chrysotile fibrils were detected. Mass calculations based on the fibre size showed that the average concentration of chrysotile was <1 ng m-3 at all sites, and only when large amosite fibres were present was the 1 ng m-3 level exceeded.

PubMed has no abstract for this study. This is the authors' abstract, copied from the article.

In plain English

This survey measured airborne fibres in 43 UK buildings (1983 to 1985): 39 with asbestos materials, mostly sprayed or trowelled asbestos or asbestos-insulated warm-air heaters, and four without. As far as possible, samples were collected under normal occupancy with windows and doors closed, and analysed by optical and electron microscopy. Optically, 31 of 235 samples (13%) exceeded 0.01 fibres per millilitre (highest 0.075). Electron microscopy showed most fibres were not asbestos. For asbestos fibres longer than 5 micrometres, only Site 7, with a visibly damaged sprayed asbestos ceiling, averaged above 0.001 per millilitre; its highest sample was 0.012 chrysotile fibres per millilitre. Average chrysotile mass was below 1 nanogram per cubic metre at every site; large amosite fibres raised seven samples from five sites above it. In the 23 buildings with asbestos warm-air heaters, averages for asbestos fibres longer than 5 micrometres were below 0.001 per millilitre, except one site averaging 0.001, where a non-working heater was dismantled, exposing its insulation. The authors concluded that, under normal occupation, buildings have very low airborne asbestos levels unless maintenance or physical attrition occurs.

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: Measurement survey of airborne asbestos and other fibre concentrations inside buildings, using membrane filter air sampling analysed by phase contrast optical microscopy and transmission electron microscopy
• Who was studied: 43 buildings in the U.K. (39 containing asbestos materials, including 23 with asbestos-containing warm-air heaters, and 4 without asbestos materials), sampled between 1983 and 1985; outdoor background samples were also collected where possible
• Exposure: Asbestos materials in buildings, mainly loose or friable types such as sprayed asbestos (amosite, chrysotile, crocidolite), trowelled amosite, plaster containing 1-5% chrysotile, and asbestos insulation in warm-air heaters. As far as possible, air was sampled under normal occupancy with minimal ventilation (windows and doors closed).
• Main results:
  • By optical microscopy, 31 of 235 samples (13%) exceeded 0.01 fibres per millilitre; the highest individual result was 0.075 fibres per millilitre
  • Electron microscopy showed that most fibres longer than 5 micrometres were not asbestos
  • For asbestos fibres longer than 5 micrometres, 30 of the 39 asbestos-containing sites did not exceed the limit of quantification
  • Only Site 7 had an average above 0.001 asbestos fibres (longer than 5 micrometres) per millilitre. This was a room with a visibly damaged sprayed asbestos ceiling, which gave the highest individual result of 0.012 chrysotile fibres per millilitre.
  • For asbestos fibres of all lengths, the site average exceeded the limit of quantification at 9 of the 39 asbestos-containing sites. Site 7 had the highest average (40 fibres per litre) and the highest individual result (250 fibres per litre).
  • Average chrysotile mass concentrations were below 1 ng per cubic metre at all sites
  • At sites with sprayed asbestos, a small number of large amosite fibres gave calculated mass concentrations above 1 ng per cubic metre in seven individual samples from five sites
  • In the 23 buildings with asbestos-containing warm-air heaters, averages for asbestos fibres longer than 5 micrometres were below 0.001 fibres per millilitre. The one exception averaged 0.001; there a heater that was not working had been dismantled with its asbestos insulation exposed. Five of these sites equalled or exceeded the limit of quantification.
  • Outdoor samples and samples from buildings without asbestos gave asbestos fibre concentrations below the limit of quantification
  • Optical and electron microscope counts of fibres longer than 5 micrometres generally agreed (regression slope 1.23, with electron microscopy giving higher counts)
• The authors' conclusion: The authors concluded that, under normal conditions of occupation, very low levels of airborne asbestos are present in buildings unless maintenance activity or some form of physical attrition is present. They also concluded that phase contrast microscopy is useful for screening buildings for possible high fibre levels.
• Limitations the authors state:
  • The survey could not cover all types of asbestos-containing products
  • Low fibre counts are imprecise; for counts under 40 fibres, individual sample results can vary by more than plus or minus 50%
  • Mass concentrations have poor precision because a single large fibre can account for much of the mass; the amosite mass results were based on counts of one or two fibres
  • Optical microscopy gives false positives because it also counts non-asbestos fibres
  • The direct preparation method measures only the respirable mass and does not count large fibre agglomerates or non-respirable fibres

Topics

The National Library of Medicine indexes this study under subjects our site covers: Asbestosis.

Medical terms in this study, explained in our Lexicon: Transmission Electron Microscopy (TEM), Chrysotile, Fibril, Amosite.

Related studies

• Composition of heavy metals and airborne fibers in the indoor environment of a building during renovation — M.T. Latif, N.H. Baharudin, et al. (2011)
• Mass concentrations of airborne asbestos in the non-occupational environment--a preliminary report of U.K. measurements — G.J. Burdett, J.M. le Guen, et al. (1984)
• Asbestos release from whole-building demolition of buildings with asbestos-containing material — R.A. Perkins, J. Hargesheimer, et al. (2007)
• Asbestos concentrations in public buildings - a preliminary report — J.M. le Guen, G. Burdett (1981)
• Airborne asbestos in public buildings — J. Chesson, J. Hatfield, et al. (1990)
• Airborne fiber control in buildings during asbestos material removal by amended water methodology — R.N. Sawyer, A.N. Rohl, et al. (1985)

Browse more research in The Annals of Occupational Hygiene, or return to medical research.