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Visual guide to asbestos risk assessment in buildings: This article discusses basic asbestos risk factors in buildings, simple visual inspection procedures, and summarizes current best judgment on removing versus leaving asbestos alone indoors. Visual inspection for asbestos is not a substitute for forensic investigation, air and dust sampling to detect asbestos contamination in buildings due to disturbance of that material. This is part of our document which assists building buyers, owners or inspectors who need to identify asbestos materials (or probable-asbestos) in buildings by simple visual inspection. Also see ASBESTOS DUCTS, HVAC a field identification guide to visual detection of asbestos in and on heating and cooling system ducts and flue vents. Green links show where you are. © Copyright 2013 InspectAPedia.com, All Rights Reserved. Author Daniel Friedman. ASBESTOS RISK ASSESSMENT - Asbestos Risk Factors
Asbestos, a mineral fiber mined from the earth and used as a fire proof insulating material as well as in other products, has been a major occupational and safety hazard of great concern since the 1930's. Out of the work place, in homes and offices, there are also potential health hazards, in particular if asbestos material is damaged, disturbed, in poor condition, or located where it is likely to suffer these effects. But often asbestos-containing material can and should simply be left alone, undisturbed. Unnecessary disturbance of asbestos materials in such buildings is at risk of creating a more severe hazard than leaving it alone. In other cases asbestos encapsulation may be recommended. The decision to leave asbestos alone, encapsulate it, or removing asbestos depends largely on the type of material, its location, its condition, and its exposure to mechanical damage or fiber release. Comments at each example shown in this document indicate the reasons that further asbestos testing or removal are likely to be needed or likely to be unnecessary. Human exposure to airborne asbestos fibers has been linked to asbestosis and is a health hazard. Here is a series of photographs of places I've found common asbestos materials in buildings, and also where I've found recognizable asbestos in a few surprise locations.
Curved asbestos fibers chrysotile. Straight asbestos fibers are amphiboles. The five amphiboles include amosite, anthophyllite, tremolite, actinolite, crocidolite. Chrysotile is the most commonly-found asbestos fiber. The carcinogenicity of asbestos varies according to fiber length and diameter. The most dangerous fibers were those longer than 8microns and less than 1.5 microns in diameter. Asbestos fibers shorter than 3-5 microns in length were reported to have a very low, if any, carcinogenicity. (According to McCrone who in turn quoted studies by King, Klosterkotter, Hilscher, Davis Stanton, Pott, eta als.) The Essential Asbestos Questions to Ask in Assessing the Asbestos Hazard Risk in a Building
McCrone's five questions are focused on the examination of a particle sample, probably an air sample of an indoor environment being tested for asbestos. Field experience suggests adding a 6th and a 7th question:
In effect, these questions assist in evaluating the potential asbestos hazard in a building. Simply looking at a snapshot of airborne asbestos particles is very unreliable. Our work examining airborne particles in a large number of buildings indicates that very significant variations in the level of airborne particles (of all kinds) occur as a result of variations in normal building activity such as whether or not people are even in the building, fans being turned on or off, windows open or shut, vacuuming of surfaces during "cleaning", etc. So a "low" number in any airborne particle measurement is not, alone, reliable in characterizing building risk. [DF] Frequently Asked Questions (FAQs)... Ask a Question or Search InspectApediaQuestions & answers or comments about making a visual determination of the level of risk based on the condition or nature of asbestos-containing materials in buildings. Ask a Question or Enter Search Terms in the InspectApedia search box just below. Technical Reviewers & ReferencesRelated Topics, found near the top of this page suggest articles closely related to this one.
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We also look at asbestos fibers in our forensic microscopy lab, but
we're addressing on-site visual inspection for asbestos here, not polarized-light microscopy such as our lab photo of 
The Home Reference Book - the Encyclopedia of Homes
