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

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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 our 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.

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

Walter 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. What is 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 ASBESTOS FLOOR TILE IDENTIFICATION 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 recognizable 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. Is the asbestos friable? 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]

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ASBESTOS FLOORING HAZARD REDUCTION
ASBESTOS-FREE INSULATION MATERIALS
ASBESTOS IDENTIFICATION IN buildings
ASBESTOS ROOFING / SIDING DUST
Asbestos Risk Assessment
Asbestos in Good Condition
Asbestos in Poor Condition
ASBESTOS REMOVAL, Amateur, Incomplete
Asbestos Removal, Certification
Asbestos Foamed-Over
Asbestos Air Ducts
Asbestos Air Duct Vibration Dampers
Asbestos Pipe Insulation
ASBESTOS MATERIAL REGULATIONS
ASBESTOS REGULATION Update
ASBESTOS REMOVAL, Wetting Guidelines
Asbestos Roofing Materials
Asbestos Roof Power Washing
ASBESTOS CEMENT & FIBER CEMENT SIDING
Asbestos in unusual places
Carbon Nanotube Materials
CEILING TILES - Asbestos-Containing
Fireproofing containing Asbestos
ASBESTOS FLOOR TILE IDENTIFICATION
Paper Duct Insulation Containing Asbestos
TRANSITE PIPE AIR DUCTS
Transite Pipe Chimneys & Flues
Transite Pipe Water Supply Piping
Urea Formaldehyde Foam Insulation UFFI
VERMICULITE INSULATION
ASBESTOS Photo Guide to Materials / Products
ASBESTOS REMOVAL, Wetting Guidelines
Asbestos Under the Microscope
DUCTS - Asbestos
DUCT INSULATION, Asbestos Paper
DUCTS, Asbestos Transite Pipe
FLOOR TYPES & DEFECTS
FLOOR TILE ASBESTOS IDENTIFICATION
FLOOR TILE HISTORY & INGREDIENTS
INSULATION IDENTIFICATION GUIDE
  ASBESTOS-FREE INSULATION MATERIALS
  ASBESTOS IDENTIFICATION IN buildings
  Asbestos Pipe Insulation
  Balsam Wool Batt Insulation
  BLOWN-IN INSULATION
  BRICK LINED WALLS
  BRICK VENEER WALL INSULATION
  Cellulose loose fill insulation
  Ceramic Insulation
  Concrete insulation, light-weight
  Cotton Insulating Batts
  Fiberglass Insulation
  Foam Board Insulation
  Foam Insulation Types - Visual Id
  Homasote & Other Insulating Board
  Icynene Foam Spray Insulation
  Mineral Wool - Rock Wool Insulation
  Paper Duct Insulation
  Perlite Insulation
  PHENOLIC FOAM INSULATION
  POLYISOCYANURATE FOAM INSULATION
  POLYISOCYANURATE FOAM BELOW SLABS
  POLYSTYRENE FOAM INSULATION
  STRESS SKIN INSULATED PANELS
  STUCCO OVER FOAM INSULATION
  SUPER HI-R INSULATION
  SUPERINSULATION RETROFIT
  VERMICULITE INSULATION

• 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

Books & Articles on Building & Environmental Inspection, Testing, Diagnosis, & Repair

• Our recommended books about building & mechanical systems design, inspection, problem diagnosis, and repair, and about indoor environment and IAQ testing, diagnosis, and cleanup are at the InspectAPedia Bookstore. Also see our Book Reviews - InspectAPedia.

Asbestos Hazard, Testing, Removal, References & Products

• Environmental Health & Investigation Bibliography - our own technical library on indoor air quality inspection, testing, laboratory procedures, forensic microscopy, etc.
• ASBESTOS IDENTIFICATION IN buildings How to find and recognize asbestos in buildings - visual inspection methods, list of common asbestos-containing materials
• 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
• Asbestos in Good Condition
• Asbestos in Good Condition
• Asbestos in Your Home U.S. EPA, Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460
• Asbestos HVAC Ducts and Flues field identification photos and guide
• Asbestos NESHAP Adequately Wet Guidance, EPA340/1-90-019, December 1990, U.S. ENVIRONMENTAL PROTECTION AGENCY, Office of Air Quality Planning and Standards, Stationary Source Compliance Division, Washington, DC 20460,original web source: http://www.epa.gov/region04/air/asbestos/awet.htm
• Asbestos paper duct wrap
• Asbestos products and their history and use in various building materials such as asphalt and vinyl flooring includes discussion which draws on Asbestos, Its Industrial Applications, D.V. Rosato, engineering consultant, Newton, MA, Reinhold Publishing, 1959 Library of Congress Catalog Card No.: 59-12535 (out of print, text and images available at InspectAPedia.com).
• Asbestos Transite Chimneys, Flues, & Pipes in buildings
• Asbestos under the microscope
• Asbestos Vibration Dampers & Asbestos in the Air Handler
• Ceiling tiles: How to recognize ceiling tiles that may contain asbestos
• Examples of unusual uses of asbestos in buildings
• 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.
• "Handling Asbestos-Containing roofing material - an update", Carl Good, NRCA Associate Executive Director, Professional Roofing, February 1992, p. 38-43
• EPA Guidance for Controlling Asbestos-Containing Materials in buildings, NIAST, National Institute on Abatement Sciences & Technology, [republishing EPA public documents] 1985 ed., Exposure Evaluation Division, Office of Toxic Substances, Office of Pesticides and Toxic Substances, U.S. Environmental Protection Agency, Washington,D.C. 20460