Asbestos Air Sampling
Air Sampling
Air sampling for airborne asbestos is performed to ensure the protection of employees outside of an asbestos regulated work area, that area barriers maintain their integrity, to document asbestos worker exposures, and to meet OSHA compliance requirements. This is accomplished via a combination of air monitoring.
Background Air Monitoring
Background air monitoring is used to determine dust levels in the ambient environment prior to an abatement project. Background monitoring shall be conducted prior to any Class I or Class II asbestos abatement project where critical barriers and enclosures are to be erected, and any other project that may disturb spray-on asbestos insulation or surfacing materials that may affect another areas' ambient condition. This is also important when other dust-generating activities outside of the containment are being conducted by other subcontractors at the same time as the asbestos abatement project. Some buildings or areas are naturally dusty and have background dust levels that may be higher than the AHERA-established clearance criteria for Phase Contrast Microscopy (PCM). If PCM will be used as the clearance criteria, background monitoring will be necessary to adjust the clearance criteria. See 29 CFR 1926.1101 section (g)(4)(ii)(B).
Perimeter Air Monitoring
Perimeter air monitoring shall be accomplished for all asbestos projects requiring a negative pressure enclosure, and near all glove bag operations (or personal sampling under some circumstances could be used instead). This monitoring is accomplished to ensure that no asbestos fibers greater than background levels representing the same area before the asbestos work began are being released from the containment into adjacent occupied areas. The results of the perimeter monitoring should be available no later than 24 hours from the end of the work shift represented by such monitoring in accordance with 29 CFR 1926.1101 section (g)(4)(ii)(B).
Employee Exposure Monitoring
Employee exposure monitoring is required to ensure that no asbestos worker is being exposed to asbestos fibers in excess of the OSHA permissible exposure limits (PEL) of 0.1f/cc for an 8-hour time-weighted average or 1.0 f/cc for a 30-minute excursion limit.
Exposure Assessments
All Virginia Tech asbestos workers performing OSHA Class I, II, and III work must be enrolled into the Environmental Health & Safety Respiratory Protection Program. Therefore, an initial exposure assessment is not required. However, personal exposure monitoring will be conducted during all Class I and II asbestos projects unless a negative exposure assessment specific to the work being accomplished has been completed and has determined that airborne concentrations at the workers breathing zone are less than the PEL or excursion limit. Periodic monitoring should be conducted that represents all classes of work at least every six months for those tasks not routinely monitored. When sufficient data is collected that indicates exposures are below the OSHA PELs, periodic monitoring may be discontinued.
Clearance Air Monitoring
Clearance air monitoring shall be conducted for all Class I and II asbestos abatement activities to ensure that the area is safe for re-occupancy. Operations and maintenance Class III activities may also be monitored depending on the specific task and the potential health hazard to building occupants. Be sure to determine which method of clearance will be appropriate for the abatement project. Clearance monitoring may also be warranted after an emergency response asbestos cleanup activity. The decision to perform air monitoring will be contingent upon the type of material, the amount, and potential health hazard to building occupants. If PCM will be used, the clearance criteria according to 40 CFR 763.90 (i)(5) is 0.01 fibers per cubic centimeter (f/cc). If Transmission Electron Microscopy (TEM) will be used, the clearance criteria is 70 s/mm2. See 40 CFR 763.90 (i)(3).
Aggressive air sampling will be conducted for all Class I activities conducted within a Negative Pressure Enclosure when the building or area is "unoccupied". All other aggressive samplings will be accomplished at the discretion of the project monitor, or as mandated by the project design. Clearance air sample cassettes should be delivered as quickly as possible to the laboratory for the earliest turn-around time if they will not be analyzed on-site by a project monitor with NIOSH 582 training.
All exposure monitoring samples should be submitted to the laboratory no later than the end of the work shift for abatement jobs scheduled during the day. For evening and night work, the air samples must be sent to the lab the next business morning. The earliest turn-around time should be requested to ensure that the results are received as quickly as possible to address any potential exposure issues. The results of personal exposure monitoring shall be communicated to the employee as soon as possible, and no later than 5 working days after receipt of results from the laboratory in accordance with 29 CFR 1926.1101(f)(5). All clearance air monitoring shall be conducted by a licensed project monitor.
Contact Information
Robin McCall-Miller, Occupational Safety Program Manager
Phone: 540-231-2341
Email: rmmiller@vt.edu