Methods of Compliance | Asbestos

Q.	What are the three basic controls required initially in ALL operations covered in the Construction standard?
A.	Regardless of the exposure levels the controls required are: use of HEPA filtered vacuums when the source of the dust/debris is damaged ACM or disturbance of ACM or PACM; use of wet methods to control asbestos fiber dispersion; and prompt disposal of asbestos contaminated waste materials. These provisions apply to, for example, employers who install asbestos-containing material (no Class designation), clean up asbestos-containing debris at a construction site (Class IV), repair a boiler covered with asbestos-containing TSI (Class I or III), and remove asbestos-containing surfacing material (Class I). Certain roofing operations, however, are not subject to these requirements.
Q.	When does OSHA consider the use of wet methods infeasible?
A.	An employer can demonstrate infeasibility if he/she can show that wet methods cannot be used due to conditions such as electrical hazards, hot surfaces, and the presence of technical equipment which cannot tolerate moisture.
Q.	What is required for the disposal of asbestos-contaminated waste?
A.	All asbestos-contaminated waste must be promptly disposed of in leak-tight containers.
Q.	What is meant by the term "air sweeping"?
A.	Where the exposure is expected to be above the PELs, OSHA requires ventilation that moves contaminated air away from employees toward a HEPA filtered exhaust device. It does NOT mean that a general building ventilation system to vent asbestos contaminated air, would be acceptable under the standard.
Q.	Is the negative pressure enclosure the only effective system for larger removal operations?
A.	Negative pressure enclosure systems are effective in many circumstances in protecting workers both within and outside the enclosure. Other systems such as glove bags and mini-enclosures can be equally effective.
Q.	What is the major difference between the negative pressure enclosure and negative air ventilation?
A.	The negative pressure enclosure system is primarily designed to keep asbestos from contaminating the building. The air pressure inside the enclosure is less than outside the enclosure. Negative air ventilation draws clean air from outside the enclosure at sufficient quantities and at strategic locations, so as to provide clean air in the worker's breathing zone and is part of the negative enclosure system.
Q.	If an employer has a variety of work activities, how does one decide which class to follow?
A.	The classes are exclusive. For example, the stripping of 50 linear feet of thermal system insulation, whether or not it has been positively identified as asbestos containing material, is Class I, for it is the removal of PACM. Repair of a valve covered by ACM is Class III, since "removal" is not taking place, if less than one glove bag of ACM has been disturbed. Removal of flooring material containing ACM is Class II. If more than one "class" of work occurs simultaneously, the work must be performed according to the highest hazard classification.
Q.	Is all asbestos activity designated by "class"?
A.	All asbestos work under the Construction and Shipyard standards is not in the "class system." The installation of new asbestos-containing products does not carry a class designation, and thus the class-specific requirements do not apply to that activity. For work that does not readily fall into one of the four classes, the employer must comply with the PEL. Work covered by the General Industry standard is not included in the "class system."

Q.	Is misting considered a "wet method"?
A.	Wet methods encompass a range of work practices. For example, when removing material which is bound in a matrix, misting may be appropriate. Removing ACM or PACM which is not so bound, or where deterioration of the ACM has occurred, would require more aggressive wetting.