Asbestos is a term for a group of naturally occurring minerals. These minerals are unique in that their molecular structure is fibrous in nature. This particular quality made asbestos minerals attractive to add to literally hundreds of building materials (pipe insulation, shingles, floor tile, mastics, fireproofing, acoustical treatments etc.). Asbestos was also used in many different types of roofing products (patching compounds, asphalt impregnated felt, shingles, tars, pitch, etc.).
Hazards of Asbestos
Asbestos is a respiratory hazard and respiratory/gastro intestinal carcinogen. Exposure to asbestos occurs when respirable fibers are released into the air and then inhaled. Since exposure occurs when asbestos is inhaled, the best way to prevent exposure is to prevent asbestos fibers from becoming airborne.
Asbestos containing materials are therefore divided into two categories: friable and non-friable. Friable means that a material is able to be reduced to a powder by hand pressure. Asbestos containing materials that are friable, by their nature, have a much greater tendency to release fibers into the air. Conversely, non-friable asbestos containing materials, by their nature, do not want to give up their fibers into the air. This class of materials must be mechanically impacted (power tools such as sanders, drills, chippers, saws, etc.) to release fibers.
There are several levels of protection to help prevent asbestos fiber release during asbestos roofing removal projects.
The first level of protection comes from the roofing material itself. As a non-friable material, the roofing products do not want to readily release their fibers. The cohesive matrix of the materials (tar, pitch, asphalt) binds the fibers together with other materials. A great deal of energy is required to separate the asbestos fibers and release it in a respirable form.
The second level of protection is in the methods of removal. The contractor is required (by University's specifications and OSHA and EPA regulations) to use non-abrasive removal techniques. In simple terms, they can only use hand tools (shovels, chisels, hammers, etc.) to strip the roofing material from the building.
The third level of protection is also a regulatory requirement. Whenever asbestos containing materials are disturbed in any manner, the material must be wet. Materials that are wet do not release respirable particles into the air.
The fourth level of protection is how the materials are handled during and after removal. Once materials are removed, they must be double wrapped in layers of 6 mil thick plastic and then sealed with duct tape. The materials also must be segregated into a dumpster used only for asbestos waste. No removed asbestos containing materials are permitted to accumulate on the roofs or the job site.
The fifth level of protection is the workers themselves. In accordance with Pima County, Arizona and Federal regulations, the workers removing the roofing materials are trained and certified in accordance with an EPA recognized training program. The contractor is certified and registered for this type of asbestos work as well.
Some Other Information
It is a little disconcerting to see persons walking around with respirators and white suits. OSHA regulations require that all persons working with asbestos containing materials wear respiratory and other personal protection equipment while they are working, regardless of other control methods in place the prevent the release of fibers. The signs around the work areas and dumpsters are also an OSHA requirement so that everyone is aware that asbestos containing materials are being removed.