Asbestosfibers are released from asbestos containing materials (ACMs). Friableasbestos containing materials release fibers more readily than encapsulatedasbestos containing materials.
Determining airborne asbestos fiber levels
The standard methodology(
MDHS100in the UK) for determining airborne asbestos fiber concentration (expressed as fibers per millitre (fiber/ml) or cubic centimetre (fiber/cm³))is via the following method:
1. Air pumps are used to suck air through a filter at 8 litres per minute for 60 minutes.
2. The filter is mounted on a slide using
3. The slide is viewing using either
Phase Contrast Microscopy( PCM), Scanning Electron Microscopy( SEM), or Transmission Electron Microscopy( TEM). Usually PCM due to cost. A PCM microscope costs approx £2500 GBP.
4. The analyst looks through the microscope and counts the number of objects which meed the
MDHScriteria for counting as potential asbestos fibers. A crowd counter may be used to count fibers per field.
5. The fibers per microscope field are extrapolated to calculate a concentration value (fiber/ml). Unfortunately this is only a "transient index of concentration" rather than an absolute value as the smallest fibers are not visible via PCM.
Comparative exposure levels to airborne asbestos fibers by activity (Fibers per millilitre)
* Environmental Exposure 0.0001 fiber/ml [http://www.bohs.org/resources/res.aspx/Resource/filename/575/Mesothelioma___Julian_Peto.pdf J. Peto, C. Rake, C. Gilham, A. Darnton & J. Hodgson, (October 2006), "Observations and speculations on mesothelioma risks and asbestos exposure in Britain", BOHS Autumn meeting, Manchester, UK] ]
* Rural environmental exposure 0.0001 fiber/ml [http://www.euro.who.int/document/aiq/6_2_asbestos.pdf World Health Organisation Air Quality Guidelines Second Edition (2000), WHO Regional Office for Europe, Copenhagen, Denmark] ]
* Controlled removal of "
Artex" (3% to 5% Chrysotile) textured decorative coating: 0.08 fiber/ml [ [http://www.hse.gov.uk/aboutus/hsc/iacs/acts/watch/010206/paper1annex2.pdf G. Burdett (Nov 2005), "Airborne fiber concentration during the removal of asbestos containing textured decorative plasters and paints and the risk to workers Report Number IFS/05/13", UK Health and Safety Laboratory] ]
* Vigorous dry scraping for 60 minutes to remove textured decorative plaster from a wall: 0.09 fiber/ml personal sample, estimated
PCME[Burdett, GJ & Scott, R (1988) "Fibre Release from Chrysotile-containing Decorative Plasters" UK HSE/RLSD Report No: IR.L/DI/88/03]
* Throwing asbestos cement sheets into lorry 0.161 fiber/ml personal [Preat, B. (1993), Surveillance de Chantiers avec Fibres-Ciment. Instituut voor Reddingswezen, Ergonomie en Arbeidshygiene, Hasselt, Belgium; Report Ref. 2240-F.]
* "Representative" Asbestos cement roof Repair: Not detected to 0.3 fiber/ml personalCONSAD Research Corporation (1990). "Economic analysis of the proposed revisions to the OSHA asbestos standard for construction and general Industry. OSHA J-9-8-0033, U.S. Dept. of Labor, Washington, DC]
* Asbestos cement sheets stacked in confined space 0.30 to 0.53 fiber/ml personal [Brown, S.K. (1987), Asbestos Exposure During Renovation and Demolition of Asbestos-Cement Clad Buildings, Am. Ind. Hyg. Assoc. J. 48 (5): 478-486.]
* Careful removal of whole asbestos insulation boards by unscrewing with shadow vacuuming and spray application of a wetting agent on unsealed surfaces: Up to 3 fiber/mlManchester Metropolitan University (2000), "HEALTH AND SAFETY ASBESTOS GENERAL GUIDANCE"]
* Opening raw material
Chrysotilefrom Chongqing, China, asbestosplant 5.8–7.5 fiber/mlE.Yano, Z.Wang, X.Wang, M.Wang, Y.Lan (2001) "Cancer Mortality among Workers Exposed to Amphibole-free Chrysotile Asbestos", American Journal of Epidemiology, Vol. 154, No. 6]
* Dry removal of sprayed (limpet) coating up to 1000 fiber/ml [http://www.ncdc.gov.uk/media/adobe/4/6/Asbestos_policy_amended230505_1.pdf North Cornwall District Council Asbestos Policy (2005)] ]
Rate of decline of asbestos fiber concentration in room air
Airborne asbestos fibers settle very slowly and in relation to their diameter.
micrometrediameter fiber is estimated to settle at 150 millimetres per minute.J. S. MOORCROFT and M. J. DUGGAN (1984) "RATE OF DECLINE OF ASBESTOS FIBER CONCENTRATION IN ROOM AIR", Environmental Sciences Division, Scientific Services Branch, Greater London Council, London SE1 7PB, U.K.]
However a 0.5 micrometre diameter fiber is estimated to settle at 4 millimetres per minute.
Thus the time for a fiber to fall 2 metres is:
* 3 micrometre fiber: 13 minutes
* 0.5 micrometre: 8 hours
* [http://annhyg.oxfordjournals.org/cgi/content/abstract/30/2/185 AIRBORNE ASBESTOS CONCENTRATIONS IN BUILDINGS G. J. BURDETT and S. A. M. T. JAFFREY Occupational Medicine and Hygiene Laboratory, Health and Safety Executive, 403 Edgeware Road, London NW2 6LN, U.K]
* [http://www.hse.gov.uk/research/hsl_pdf/2006/hsl0619.pdf G.Burdett and G.Revell (2006), "Summary Report On Additional Work Carried Out On The Monitoring Of Chrysotile Containing Textured Decorative Coatings" UK HSL/2006/19]
* [http://www.hse.gov.uk/research/hsl_pdf/2007/hsl0711.pdf G.Burdett (2007), "Investigation of the chrysotile fibres in an asbestos cement sample" UK HSL/2007/11]
Wikimedia Foundation. 2010.
Look at other dictionaries:
Asbestos — For other uses, see Asbestos (disambiguation). Fibrous asbestos on muscovite … Wikipedia
Asbestos and the law — This article concerns asbestos related legal and regulatory issues.BackgroundIn the late 1800s and early 1900s, asbestos was considered an ideal material for use in the construction industry. It was known to be an excellent fire retardant, to… … Wikipedia
Asbestos abatement — Many buildings contain asbestos, which was used in spray applied flame retardant, thermal system insulation, and in a variety of other materials. Asbestos was sometimes flocked above false ceilings, inside technical ducts, and in many other small … Wikipedia
Asbestos (disambiguation) — Articles on Asbestos include:* Asbestos, the mineral * Asbestos abatement * Asbestos and the law * Asbestos Ceramic * Asbestos Convention, 1986 * Asbestos fibers * Asbestos Strike, a 1949 asbestos mine strike in Canada * Asbestosis * Baron Budd… … Wikipedia
asbestos — asbestine /as bes tin, az /, asbestous, adj. asbestoid, asbestoidal, adj. /as bes teuhs, az /, n. 1. Mineral. a fibrous mineral, either amphibole or chrysotile, formerly used for making incombustible or fireproof articles. 2. a fabric woven from… … Universalium
asbestos cement — noun : a hardened mixture of asbestos fibers, portland cement, and water used in relatively thin slabs for shingles, wallboard, and siding * * * a compound of asbestos fiber and Portland cement formerly used for various nonstructural building… … Useful english dictionary
Asbestos Curtain — In the 1890s, stages began to be equipped with drop curtains that had asbestos fibers woven into them and could be lowered as a fire barrier between the stage area and the auditorium. Unfortunately, most backstage fires could not be so easily… … The Historical Dictionary of the American Theater
asbestos — as•bes•tos [[t]æsˈbɛs təs, æz [/t]] n. 1) mir a fibrous mineral, either amphibole or chrysotile, formerly used for making incombustible or fireproof articles and in building insulation 2) a fabric woven from asbestos fibers, formerly used for… … From formal English to slang
asbestos — [as bes′təs, azbes′təs] n. [ME asbestus < L asbestos < Gr, inextinguishable < a , not + sbestos < sbennynai, to extinguish: first applied in Gr & L to unslaked lime or a mineral other than asbestos] any of several grayish minerals, as … English World dictionary
Asbestos — Asbestus As*bes tus, Asbestos As*bes tos (?; 277), n. [L. asbestos (NL. asbestus) a kind of mineral unaffected by fire, Gr. ? (prop. an adj.) inextinguishable; a priv. + ? to extinguish.] (Min.) A variety of amphibole or of pyroxene, occurring in … The Collaborative International Dictionary of English