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How to conduct a visual inspection for asbestos risks in buildings Essential questions to ask in assessing the asbestos hazard risk

This page discusses basic asbestos risk factors in buildings and summarizes current best judgment on removing versus leaving asbestos alone indoors.

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 HVAC Ducts a field identification guide to visual detection of asbestos in and on heating and cooling system ducts and flue vents.

© Copyright 2008 Daniel Friedman, All Rights Reserved. Information Accuracy & Bias Pledge is at below-left. Use links at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

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.

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 my lab photo of crocidolite.

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.

Asberstos 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 posed the following 5 key things that a building owner should know in deciding what to do about possible asbestos in his or her building:

1. Are fibers present?
   
   
2. Are they asbestos?
   
   
3. If there are asbestos fibers present, in what proportion of the total?
   
   
4. What other substances are present (cellulose fibers, mineral wool, fiberglass, vermiculite, talc, perlite, pumice, diatomaceous earth, organic fibers, clays, glass powder, quartz, calcite, gypsum (drywall dust), plaster dust, etc.) [some additions by DJF]
   
   
5. Friability (how easily are particles released into the air), effectiveness of existing isolation or encapsulation. [McCrone refers to asbestos materials which are friable - and so are more likely to be present in air, dust, or the environment. The floor tiles described by the box at left do not release high levels of asbestos fibers unless they are subjected to abrasion. See Floor Tiles Containing Asbestos for details. -- DF]

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:

6. Is there obvious, visibly reconizable asbestos or asbestos-suspect material in the building? (Some building materials are unmistakably asbestos or asbestos-containing and can be identified without lab analysis. They are shown in photographs provided below.)
7. Perhaps re-stating #5 above in a compound question on friability: what is the general condition of the asbestos material? Is it damaged and thus more likely to be friable? Is it in a location which is likely to move asbestos particles into an occupied space by air movement or by human movement?

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]

Continue reading in this article using direct links to the sections listed below, or

Use links just below or at the left of each page to navigate this document or to view other topics at this website. Green links show where you are in our document or website.

IDENTIFICATION of ASBESTOS in BUILDINGS
Asbestos Risk Assessment
Asbestos in Good Condition
Asbestos in Poor Condition
Asbestos Removal, Amateur, Incomplete
Asbestos Foamed-Over
Asbestos Air Ducts
Asbestos Air Duct Vibration Dampers
Asbestos Pipe Insulation
Asbestos Roofing Materials
Asbestos Siding Materials
Asbestos in unusual places
Carbon Nanotube Materials
Ceiling Tiles Containing Asbestos
Fireproofing containing Asbestos
Floor Tiles Containing Asbestos
Paper Duct Insulation Containing Asbestos
Transite Pipe Chimneys & Flues
Transite Pipe Air Ducts
Urea Formaldehyde Foam Insulation UFFI
Vermiculite Insulation Containing Asbestos
Other Asbestos-Containing Materials
Asbestos Under the Microscope
Insulation Material Identification Guide
Mold Growth Resistance of Foam Insulation
Asbestos-Free Insulation Materials
Insulation Materials
  Asbestos Pipe Insulation
  Balsam Wool Batt Insulation
  Cotton Insulating Batts
  Cellulose loose fill insulation
  Fiberglass Insulation
  Foam Board Insulation
  Foam Spray Icynene Insulation
  Mineral Wool/Rock Wool Insulation
  Paper Duct Insulation
  Perlite Insulation
  Vermiculite Insulation

Technical Reviewers

Particular thanks are due to experts and also consumers who read these articles and suggest corrections, changes, and additions to the material. Content suggestions, technical corrections and content critique are invited for any of the content at our website.

• Daniel Friedman - principal author/editor of the InspectAPedia ^TM Website
• 3/07: thanks to Gary Randolph, Ounce of Prevention Home Inspection, LLC Buffalo, NY, for attentive reading and editing suggestions. Mr. Randolph can be reached in Buffalo, NY, at (716) 636-3865 or email: gary@ouncehome.com
• 06/07: thanks for photographs of transite asbestos heating ducts, courtesy of Thomas Hauswirth, Managing Member of Beacon Fine Home Inspections, LLC and (in 2007) Vice President, Connecticut Association of Home Inspectors Ph. 860-526-3355 Fax 860-526-2942 beaconinspections@sbcglobal.net
• Technical reviewers are invited to comment or ask questions - contact us

More expert information on Asbestos Identification, Recognition, & Testing

More Information on Asbestos Contamination, Other Airborne Fiber Hazards, & Building Diagnostic Inspections and Repairs

• Asbestos: How to find and recognize asbestos in Buildings - visual inspection methods, list of common asbestos-containing materials
• Asbestos HVAC Ducts and Flues field identification photos and guide
• Fiberglass: Indoor Air Quality Investigations: Health Concerns About Airborne Fiberglass: Fiberglass in Indoor Air from HVAC ducts, and Building Insulation
• Enviro-Scare: Electric Power Lines, Electromagnetic Fields, Cancer Risk, & "Enviro-Scare" - The Normal Curve Cycle of Public Fear of Environmental Issues
• Dust from the World Trade Center collapse following the 9/11/01 attack: the lower floors of this building contained spray-on fire-proofing asbestos materials.
• Asbestos Information Links: Asbestos Detection, Testing, Recognition, Hazards, Field Photos, and Information Sources, including health-related links such as legal services and information about mesothelioma and other cancers.
• Asbestos Identification and Testing References
• Asbestos Identification, Walter C.McCrone, McCrone Research Institute, Chicago, IL.1987 ISBN 0-904962-11-3. Dr. McCrone literally "wrote the book" on asbestos identification procedures which formed the basis for current work by asbestos identification laboratories.
• Stanton, .F., et al., National Bureau of Standards Special Publication 506: 143-151
• Pott, F., Staub-Reinhalf Luft 38, 486-490 (1978) cited by McCrone

Building & Environmental Inspection, Testing, Diagnosis, Repair, & Problem Prevention Research & Advice

The Mold Information Center: What to Do About Mold in Buildings, When and How to Inspect for Mold, Clean Up Mold, or Avoid Mold Problems

Home Inspection Construction Consulting Services & advice for home buyers

Use this simple, economical mold test kit by following our instructions on how to collect and mail mold samples to our lab

Environmental Inspection, Testing, & Diagnosis On-Site IAQ, Gas, Air Testing, Mold Investigation, Sick Building Diagnosis, Lab Services, & Remediation Plan Preparation - indoor air quality testing, problem source determination, supporting lab work, written remediation plan addressing removal of environmental and other hazards and prevention of their recurrence.

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