3.1 History of Asbestos Use, Mineral Types & Physical Characteristics

3.1 History, Mineral Types & Physical Characteristics of Asbestos

Quick Answer: Asbestos is a regulatory and commercial term for the fibrous (asbestiform) varieties of six naturally occurring silicate minerals. Chrysotile belongs to the serpentine group. Amosite, crocidolite, anthophyllite, tremolite, and actinolite belong to the amphibole group. Asbestos was valued because it resists heat and fire, has high tensile strength, resists chemicals and decay, absorbs sound, and was cheap. U.S. use peaked in the early 1970s. Because fibers split into microscopic fibrils that stay airborne and are inhaled deep into the lungs, disturbing asbestos is regulated even where the material itself looks harmless.

Why "General Topics" Matters on the Exam

The New Jersey worker and supervisor course rules (N.J.A.C. 12:120-6.6) begin with "background information on asbestos: history of asbestos use and physical characteristics of asbestos." The Pearson VUE outline devotes about 8% of each exam to this area. Expect questions on mineral names and groups, where asbestos was used, why it was used, how fibers behave in air, and why age of construction matters.

The Six Regulated Minerals

The New Jersey statute (N.J.S.A. 34:5A-34), the joint rules (N.J.A.C. 12:120-2.1), the UCC subcode (N.J.A.C. 5:23-8.2), and federal rules name the same six minerals.

Serpentine vs. Amphibole

• Chrysotile is a sheet silicate whose layers roll into hollow tubes, which is why its fibers are soft and curly. It is somewhat more soluble in lung fluid than amphiboles. It is still a known human carcinogen that can cause asbestosis, lung cancer, and mesothelioma.
• Amphiboles are double-chain silicates. Their fibers are straight, rigid, and very durable in lung tissue. Crocidolite and amosite are considered the most potent for mesothelioma.

The term asbestiform matters: the same minerals also occur in non-fibrous forms that are not regulated as asbestos. Laboratories identify asbestos by fiber shape plus optical or electron-beam properties (see Section 5.3).

Physical Properties That Drove Its Use

• Heat and fire resistance: Asbestos does not burn and insulates well, so it went into boiler and pipe insulation, fireproofing, fire doors, and gaskets.
• Tensile strength and flexibility: Fibers reinforce cement, plastics, and asphalt and can be woven into cloth.
• Chemical and biological resistance: It resists acids (especially the amphiboles), rot, and corrosion.
• Sound absorption: Acoustical plasters and ceiling tiles used it to deaden sound.
• Low cost and easy blending: Asbestos could be mixed into almost any binder, which is why it appears in thousands of products.

Aerodynamic Characteristics

Federal Model Accreditation Plan courses must teach the aerodynamic characteristics of asbestos. Key points:

1. Fibers split lengthwise. A bundle breaks into thinner and thinner fibrils, so disturbing ACM releases enormous numbers of fibers too small to see.
2. Fibers settle slowly. A particle's fall speed depends mostly on its diameter. Thin fibers can stay suspended for hours in still air and are carried by drafts, HVAC systems, and foot traffic.
3. Long, thin fibers penetrate deeply. Because they align with airflow, fibers much longer than they are wide can pass the nose and upper airways and reach the deep lung.
4. Visible dust is not the whole hazard. Air can look clean while carrying hazardous fiber concentrations. That is why air sampling, not eyesight, is used for clearance, and why NESHAP treats visible emissions as proof that material was not adequately wet.

Where Asbestos Was Used in Buildings

These three categories drive both inspection sampling rules and OSHA's work classes (Sections 2.3, 5.1, and 5.2).

A Short Regulatory History

The New Jersey Connection

New Jersey was a center of asbestos manufacturing. Manville, in Somerset County, was home to a large Johns-Manville asbestos products plant. Insulation workers in the New York-New Jersey area were among the first groups whose disease rates were systematically studied. The state's 1984 licensing law grew out of this history, and New Jersey layers its own licensing, notification, and building-code rules on top of the federal standards.

Why Old Buildings Are Presumed to Contain Asbestos

The 1970s bans did not remove material already installed, and some non-banned products stayed in use for years. OSHA therefore defines presumed asbestos-containing material (PACM) as thermal system insulation and surfacing material in buildings constructed no later than 1980. PACM must be treated as ACM unless an accredited inspection and laboratory analysis rebut the presumption. Many resilient floor coverings, mastics, roofing products, and cement products from later years can also contain asbestos, so they must be tested before disturbance even though they are not PACM.

New Jersey Rule on Applying Asbestos

The subcode still regulates application of asbestos (N.J.A.C. 5:23-8.12):

• No spraying of asbestos, or of friable material containing more than 0.25% asbestos by weight, on any building (see also N.J.A.C. 7:27-17).
• No troweling of asbestos material by hand during construction or renovation.
• The only permitted applications are products in which asbestos is securely bound in a solid matrix before application, such as floor tiles.

Exam Traps

• Chrysotile is regulated asbestos. It is serpentine and less biopersistent, but it is still a carcinogen.
• "Amosite" is a trade name. It comes from "Asbestos Mines of South Africa," not from a mineral species. The mineral is cummingtonite-grunerite.
• PACM covers only TSI and surfacing. Floor tile in a 1975 building is not PACM, but it is suspect ACM that must be sampled or assumed positive.
• The 1989 ban did not stand. Many asbestos products remained legal after 1991, which is why post-1980 buildings can still contain ACM.