Seals and Sealants
Using asbestos-containing products for caulking around doors and windows was common until the 1970s, when using asbestos in building materials was banned in the United States. Caulk benefited from the weatherproof and insulating strengths of asbestos, but it poses health risks when worn, flaking or being replaced. Older homes might have old caulking with asbestos or remnants of it around windows and doors, though homes from the past 20 years likely do not [source: Howard University].
Until the asbestos bans, using asbestos products to improve gasket seals on furnace doors, such as those on old coal chutes, for example, also was common due to their heat resistance and ability to form and hold a tight pressure seal [source: CPSC, et. al]. Removing or cleaning old oil or coal furnace doors or making structural improvements around them can release particle chips from these dried seals, releasing asbestos dust.
If buying or renting an older home with decades-old caulking or basement coal chutes and stoves, enlist the services of a professional to check for asbestos before replacing or removing any parts.