During the early years of the 20th Century, boilers were used both to provide heat (old-time steam radiators are still common in older buildings, but are rarely functional) as well as energy to drive machinery; in fact, steam locomotives were used on the nation’s commercial railroads until 1960. Breaching insulation was used to protect the area in the event a boiler or boiler duct (pipe) should burst open.
Such breaching insulation is still commonly used for modern HVAC conduits and piping, but other materials have largely replaced asbestos. Asbestos breaching insulation in structures built prior to 1980 is very likely to contain asbestos. It is also a potential hazard underneath city streets, as was dramatically illustrated in Boston and Manhattan last year. This was dramatically illustrated when the aging steam pipes under the streets suddenly exploded with great force, spreading asbestos fibers over large areas.
The greater danger however is the asbestos-containing breaching insulation that is present in older homes and apartment buildings. As this material ages, it invariably begins to crumble, releasing microscopic asbestos fibers into the air; in this state, it is known as friable.
These friable asbestos fibers may either be chrysotile (“white”) asbestos, or amphibole (“blue” or “brown”) asbestos. The former kind is far more common, having been used in 95% of all construction applications over the decades, and technically still legal in the U.S. and Canada (which is one of the world’s last major producer of asbestos). Chrysotile fibers are soft and curly, but abrasive; when ingested into the lungs, they literally scratch the interior surfaces of the aveoli, or air sacs. This in turn causes the build-up of scar tissue, which reduces lung capacity over time; this condition is known as asbestosis.
Amphibole insulation – which also includes tremolite, a common contaminant of talc and vermiculite products – is made up of fibers that are stiff and shaped like microscopic needles that actually bore through lung and other tissues from the inside out, resulting in the cancer known as mesothelioma.
While old breaching insulation is more likely to be of the chrysotile variety, there is no way to know for certain without microscopic analysis – and both varieties pose serious health hazards. If you suspect the presence of asbestos-containing materials in your home or building, the best course of action is to contact local health authorities, who can advise you on the most effective course of action.