Asbestos-Containing Products To Check For

The safest assumption about any material that may contain asbestos is that it is asbestos. The material should be handled carefully until proven otherwise. Positive identification in "bulk" materials (as opposed to air samples), such as samples taken from building materials, requires polarizing light microscopy (PLM). PLM is only available through a laboratory certified by the U.S. Environmental Protection Agency. While other labs may have PLMs, EPA requires that technicians are trained to recognize asbestos fibers in the samples they examine. The National Institute of Standards and Health (NIOSH) is considering new research on methods for identifying even finer fibers, especially in air samples where the real danger of asbestos contamination exist.

The difficulty in identifying asbestos is that it is not just one mineral, but a "habit" that at least six minerals share while forming long crystals so thin that they can be referred to as fibers. While nearly all of the building materials and consumer goods that intentionally contain these fibers are limited to chrysotile, or white asbestos, there have been occasions when other "asbestiform" minerals were found contaminating other uses, and these other minerals are much more toxic.

A good place to start asbestos awareness is when buying new building materials. Check the "Material Safety Data Sheet" for any products that may contain asbestos. Building-supply sources are required by law to make this sheet available.

Of course, the real challenge is figuring out what someone else has placed in your house before you owned it. From inside to out, and roughly from attic to basement, any changes or renovations can stir up asbestos fibers if they are present. If the home has deteriorating asbestos-containing materials (ACMs) or renovation plans require the disturbance of ACMs, taking into account the ACMs in your plans and budget are important.

What Products Should I Look For?

• Asphalt roofing shingles or roll roofing, and felts for asbestos-containing roofing materials. Especially on flat roofs that have been simply re-covered instead of stripping off the old materials.
• Cement roofing shingles and tiles are probably fairly old, though they have been manufactured from the 1930s up to today. From the ground, cement roofing may look like slate or wood, but when you touch it, it may feel as warm or cool as other cement, and have a rough feel. If you are inspecting a home to buy, take a close look at the condition of a cement roof. Once it starts to break down, you have little choice but to replace the whole thing.
• Roof patching cement -looks about the same with or without asbestos. Your best gauge is the rest of the roof and when it was last worked on. The longer it has been there, the more likely it contains asbestos.
• Flexible, non-metallic base flashing around roof protrusions such as vents - age and the rest of the roof is your best guide. Most roofers now use metal flashing.
• Cement sidings -most commonly shingles, but also clapboards from a shorter period in the mid-1940s. Very few are putting new asbestos siding on their houses in the United States today, though there is no legal barrier. The asbestos fibers are well encapsulated in these products. The old products, most popular in the 1940s and '50s, were often striated, or ridgy, which unfortunately makes them susceptible to scraping, and that can break down the matrix and release fibers into the air.
• Tremolite sand, made from crushed rock, has much bigger pieces than beach sand.
• Loose or batt insulation - may be invisible in the walls, but especially if you find fluffy, grayish-white material between the attic rafters. You can try peering down the walls too, or carefully pull an electrical switch or outlet from an outside wall.
• Insulation board on walls - under paint it may look just like today's gypsum wallboard, but age and a slightly more plaster-like feel and sound can tip you off; you will also be more suspicious if the outside walls are done with a different material than the inside ones.
• Pipe coverings - blanket-like or preformed around elbows and valves. They may also look like corrugated cardboard, or tape A canvas-type cloth covering is a tip-off to the blanket coverings, especially if it looks gray or white (these products were made from 1926 to 1975). The cardboard kind of pipe wrap was used especially on steam pipes, from as early as 1910 and possibly as late as 1980, and is sometimes referred to as "aircell." The same dates apply to asbestos-paper tape.
• Clay-based plumbing putty - almost no clues, but the apparent time elapsed since the plumbing was worked on; the material was used from 1900 to 1973.
• Flexible connections for ventilation ducts - usually look papery and often are accordion-pleated to allow them to connect two rigid ducts.
• Fuse-box linings and insulation in the electrical boxes behind wall switches and plugs, in recessed lighting, and in ceiling fixtures and freestanding lamp sockets - grayish, thick, and sometimes slightly fuzzy-looking paper or cardboard.
• Papery or fabric insulation on electrical wires - these materials are electrical insulators only with asbestos; they were used from about 1901 to as late as the 1980s.
• vinyl (1950-80) or asphalt (1920-80) floor tiles, sheet flooring (1950-80), and the mastic that holds them down (from 1945 to as late as 1980). Paper "felt" used as underlayment or fused to the back of the vinyl and mastic for carpet and ceiling tile Age is about the only clue, though in fact these materials are still legally manufactured, their use has declined rapidly since about 1978.
• Rubber stair treads and risers - look for signs of age (deterioration).
• Acoustical and decorative plasters for walls and ceilings.
They may have been blown on or troweled on and were especially popular in the 1950s and '60s (though they were introduced in the '30s and not abandoned until 1978). The blown-on ceiling treatments are sometimes known as "popcorn" or "cottage cheese" because that's how they look, but not all popcorn ceilings contain asbestos. The safest position is to be suspicious of any textured paint or patching compound that was put on your walls and ceilings before 1978. Estimates say that half the multistory buildings put up in the 1950s through the '70s have some kind of sprayed-on asbestos-containing material.
• Spackle (1930-78) and joint compounds (1945-77) - no distinction from post-asbestos materials except keeping company with suspicious wallboard or plasters.
• Ceiling tiles and the panels that lie in suspended ceilings - age is the only reliable clue. The most suspicious tiles are from the late 1940s and '50s, about a foot square, and tend to be off-white, yellowish, or light gray, with a fairly solid or evenly perforated surface (rather than the marbled-looking surface of later tiles).
• Caulking and putties, especially around places that are subject to high heat - look for signs of age (deterioration). Asbestos was introduced to some putties as early as 1900 and used as late as 1973.
• Millboard or Rollboard -if you can see an edge, you may be able to identify two distinct layers of roughish paper with or without another layer between Beginning as early as 1925, this product was particularly used in office partitions, enclosed decks and even exterior walls, garage paneling, linings for stoves, electrical boxes, and fireproofing for security boxes, safes, and file storage.
• Chalkboards - newer than slate, older than painted surfaces.
• Cement pipes - most often found as sewer lines and water mains; whitish, hard, but not necessarily old (1935 to the present) Asbestos allows manufacturers to cast very strong cement pipes that are unusually light weight for their thickness.
• Block insulation - an old furnace (1890 to 1978), especially one that originally burned coal or wood, may look as though it's encased in the plaster once used to set broken arms and legs, plump and softish, though it isn't.
• Doors and gaskets on oil and coal furnaces and some wood stoves - the age of the appliance and condition of the gasket are the best clues.
• Insulation on heating ducts - greyish cardboard is most likely asbestos. Check inside the ducts for the same purpose.
• Tape and insulation sealing hot-air registers - few clues other than age (1901-1980).
• Laboratory and range hoods - look again for that grayish cardboard; if it looks like paper and is being used in something old that generates or is used near heat or flame, it's probably asbestos.
• In-cabinet ovens and dishwashers installed up to the mid-1970s - asbestos insulation is probably well hidden, but you should be aware of it for when you need to remove the appliance. Other appliances, such as freezers and water heaters, may also have hidden asbestos under their skins.
• Small appliances such as portable dishwashers, toasters, clothes dryers, popcorn poppers, broilers, electric blankets, and slow cookers. Almost anything that works with heat has had parts made with asbestos-containing materials. The heating coils in space heaters and hair dryers made before 1979 may be wrapped in asbestos material and backed with asbestos insulation.
• Artificial ashes and embers in gas fireplaces and heaters. The older the appliance the more likely it contains asbestos.
• Papers or cement sheets on the floors and walls around fireplaces, wood stoves, and boilers - age is the best clue, beginning in about 1930 and continuing to the present.
• Vinyl wall coverings - very difficult to tell.