Many buildings contain asbestos, which was used in spray-applied flame retardant, thermal system insulation, and in a variety of other materials. Asbestos was sometimes "flocked" above false ceilings, inside technical ducts, and in many other small spaces where firefighters would have difficulty gaining access. Structural components like asbestos panels were also used. In residences, asbestos was often a component of a type of flocked acoustic ceiling called "popcorn ceiling" or "cottage cheese ceiling", until its production was banned in the U.S. in 1978. However, the ban allowed installers to use up remaining stocks, so houses built as late as 1986 could still have asbestos in their acoustic ceilings. The only way to be sure is to remove a sample and have it tested by a competent laboratory.
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Depending on how and where asbestos was applied, it might not pose any risk to most users of the building. If the fibers cannot become dislodged, they cannot be inhaled, and thus the asbestos poses no risk.
However, some methods of applying asbestos, particularly flocking, allow asbestos fibers to gradually drop off into the air. Asbestos poses hazards to maintenance personnel who have to drill holes in walls for installation of cables or pipes.
Even if the workers are protected, such maintenance operation may release fibers into the air, which may be inhaled by others. Interventions in areas where asbestos is present often have to follow stringent procedures.
When asbestos fibers can easily be made into airborne dust, the material is known as friable. For example, a "popcorn ceiling" is extremely friable, whereas asbestos floor tile is considered non-friable.
If removal is to be performed when users are still present in the building, it is usually necessary to relocate some users temporarily. Typically, the part of the building from which asbestos is being removed has to be sealed off in order to prevent contamination of the other areas. Methods of sealing off an area often include the use of Polyethylene film, duct tape and negative air pressure machines which are fitted with HEPA filters. The idea is that the contained area is pulling fresh air in as to not allow asbestos fibers into the surrounding environment.
Only a special vacuum cleaner that's designed for asbestos containment (class H) can be safely used when cleaning up during and after asbestos removal. Ordinary vacuum cleaners cannot be used, even those fitted with a HEPA filter.[1] An ordinary vacuum cleaner will expel the asbestos fibres into the room air.
If the building is closed to normal users, it may be necessary to seal it off from outside atmosphere so that no accessible air is contaminated. Examples of asbestos removal enterprises include the Jussieu Campus (begun circa 1996 and still going on as of 2005[update]) and the Tour Montparnasse (in 2005, projected duration was three years if the tower was emptied of its users, and ten years if it were not).
Removal is not the only means of asbestos abatement. Asbestos and asbestos-bearing materials may be "enclosed" or "encapsulated" to prevent building occupants from being exposed to the fibers.
An asbestos-containing building that is to be torn down may have to be sealed (see third picture on right), and to have its asbestos safely removed before ordinary demolition can be performed. The asbestos removal may take longer and cost more than the actual demolition. For example, the former seat of parliament of East Germany, the Palast der Republik, was stripped of most of its asbestos between 1998 and 2001, before it was finally demolished starting in 2006.