17 Asbestos Safety Manual Environmental Health and Safety F Control Measures Notices and Labeling In conjunction with the asbestos building surveys and to meet Occupational Safety and HealthAdministration (OSHA) requirements, the entrances to mechanical rooms and custodial closets into which employees are expected to routinely enter Environmental Health and Safety (EH&S) has posted one of the following signs: • Red Danger Sign to indicate that asbestos-containing materials (ACM) are present, their location, and the appropriate work practices to avoid potential exposure. • Green Notice Sign to indicate no suspect materials in the room or whether suspect materials have been tested and determined not to contain asbestos. Activities Involving Potential Exposure OSHA regulations define exposure at or above the permissible exposure limit (PEL) of 0.1 fibers per cubic centimeter (f/cc) for 30 or more days a year. Asbestos-containing materials that can be reduced to powder by hand pressure are considered to be friable. Friable materials are more likely to release fibers into the air where they can be a source of exposure. Some non-friable materials may become friable if they are cut, drilled, or damaged by water. The presence of asbestos alone in a building does not mean that the building occupants are necessarily endangered. As long as asbestoscontaining materials remain in good condition, exposure is unlikely. When damaged, building maintenance, repair, renovation, or other activities may disturb ACM, creating a potential hazard to building occupants. Some asbestos fibers can take up to 80 hours to settle. An airborne asbestos fiber can move laterally with air currents and contaminate spaces distant from the point of release. Fiber release may occur in several ways: Fallout - Old and/or deteriorated asbestos fibers may become airborne due to damage or destruction of the bonding agents used to hold the asbestos product together. Fallout may result in fibers being deposited on horizontal surfaces over time due to humidity, vibration, or aging. Contact - Striking, cutting, drilling, etc. may release fibers into the environment. Air erosion is also a form of contact and may release fibers to the environment from damaged or exposed material. Re-entrainment - Sweeping, dusting, or unfiltered vacuuming of settled dust may result in asbestos fibers being re-suspended into the atmosphere. Contact damage to asbestos ceiling material
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