Asbestos Mud Materials

Joint compound is a substance similar to plaster used to seal seams between sheets of drywall. It is primarily used in building construction and renovations. 

Asbestos-containing drywall joint compound was packaged as either ready-mix (an application-ready product) or as dry mix (a powder that requires water in order to form a paste for application). After adding water to the dry mix joint compound, the product was mixed, thereby releasing a mass of asbestos-containing dust into the breathing area of the worker who mixed the compound. "At 1.5 meters distance away, readings were averaged at 47,200,000 individual asbestos fibers per cubic meter of air. Those working in the background up to 6 meters away were exposed to an average of 5,800,000 fibers per cubic meter of air, and those in an adjacent room approximately 10 meters away were exposed to an average of 2,600,000 fibers per cubic meter of air."1

After the asbestos-containing joint compound was applied and dried, the compound was sanded to achieve a smooth and seamless area between drywall boards. Asbestos-containing joint compound was sanded by hand with either a hand-held sanding block or, if the work is conducted overhead, with a pole sander. Hand-sanding targets an area within an arm's length of the worker, whereas pole-sanding is conducted overhead and on hard-to-reach areas, such as a ceiling. The process of hand-sanding and pole-sanding asbestos-containing joint compound released millions of asbestos fibers into the atmosphere. "At 1.5 meters distance, hand-sanding released an average of 5,300,000 fibers per cubic meter of air, and pole-sanding potentially releases up to 10,000,000 fibers per cubic meter of air."2 Even when studying the asbestos fiber levels from sanding (hand-sanding or pole-sanding) in an adjacent room, "the atmospheric asbestos fibers count averages 4,000,000+ fibers per cubic meter of air."3 Sanding took place  at least three times or more. The mere process of sanding asbestos-containing joint compound exposed a worker to nearly 30 million fibers (based on pole-sanding data).

The process of mixing and sanding asbestos-containing joint compound created a vast amount of dust, and it was common for excess dust and debris to be swept up with a broom. Unfortunately, this process created and re-emitted asbestos-containing dust back into the breathing areas of workers and individuals that were in close proximity to the clean-up. "At 15 minutes after sweeping, it was recorded that 41,400,000 fibers per cubic meter remained floating in the air. At 35 minutes, 26,400,000 fibers per cubic meter remained"4. Whether a worker was exposed to one asbestos fiber or to 30 million, there is absolutely no safe level of exposure.


1 Rohl, A. N., A. M. Langer, I. J. Selikoff, and W. J. Nicholson. "Exposure to Asbestos in the Use of Consumer Spackling, Patching, and Taping Compounds." SCIENCE 189 (1975): 551-53. Print.

2 Rohl, A. N., A. M. Langer, I. J. Selikoff, and W. J. Nicholson. "Exposure to Asbestos in the Use of Consumer Spackling, Patching, and Taping Compounds." SCIENCE 189 (1975): 551-53. Print.

3 Rohl, A. N., A. M. Langer, I. J. Selikoff, and W. J. Nicholson. "Exposure to Asbestos in the Use of Consumer Spackling, Patching, and Taping Compounds." SCIENCE 189 (1975): 551-53. Print.

4 Rohl, A. N., A. M. Langer, I. J. Selikoff, and W. J. Nicholson. "Exposure to Asbestos in the Use of Consumer Spackling, Patching, and Taping Compounds." SCIENCE 189 (1975): 551-53. Print.