The fact is, we're all exposed to asbestos, although usually in such small quantities that it poses no threat. The typical air concentration of asbestos fibers is 0.00001 to 0.0001 fibers per milliliter. In comparison, U.S. workplaces are limited to exposing employees to 0.1 fiber/mL, and significant exposure is considered years of exposure to 0.125 to 30 fibers/mL [source: Agency for Toxic Substances and Disease Registry].
In nature, the fibrous asbestos is embedded in rocks, most commonly ultramafic rock (a type of igneous rock), which is found in much of California and near fault zones. Not all ultramafic rock contains asbestos, but all ultramafic rock has the potential to contain veins of asbestos [source: Agency for Toxic Substances and Disease Registry]. Mining areas in the eastern United States have also been discovered to contain naturally occurring asbestos. To obtain the asbestos for use -- and to make it airborne -- the rock must be crushed to release the fibers.
In commercial products, asbestos is still found in heat and acoustic insulation, fire proofing, and building materials like roofing and flooring. Additionally, asbestos can be found in older automotive parts like disc brake pads and drum brake linings, which used asbestos because of its friction properties [source: Asbestos Project Plan]. Banned new products include flooring felt, cement shingles (also known as asbestos siding), and corrugated, commercial and specialty paper. However, older material that used asbestos can still be found widely [source: EPA].
Asbestos testing should be conducted by licensed government agencies, and trained asbestos abatement professionals should be the only ones performing the removal. In some cases, it's safer to seal the asbestos in rather than remove it. For more information on getting asbestos out of your house, see Is it safer to remove asbestos from a building or leave it there? In cases of emergency asbestos exposure -- when Hurricane Katrina hit New Orleans or the fall of the World Trade Center, for example -- the best thing to do is get out of the area (keeping your mouth and nose covered with a wet cloth when possible) and contact your state and local agencies or the Environmental Protection Agency for more information on proper testing, removal or containment.
Now that you know what and where to look for asbestos, we'll talk about warning signs to watch out for if you've been exposed to asbestos.