1. (a) At the completion of an asbestos abatement, or phase of that abatement, but prior to dismantling the containment and decontamination system, the owner or operator shall obtain the services of an independent industrial hygienist to conduct clearance air sampling.
2. (b) Prior to clearance sampling, the independent industrial hygienist shall conduct a thorough visual inspection of the work area for the presence of visible residue.
3. (c) If visible residue is found by the independent industrial hygienist, the owner or operator shall continue cleaning the work area as specified in Env-A 1812.01(f).
4. (d) After determining that no visible residue remains in the work area, the independent industrial hygienist shall take sufficient volumes of air for clearance sampling to accurately determine, to a 95 percent probability, fiber concentrations to 0.010 fibers/cubic centimeter (f/cc) of air.
5. (e) The independent industrial hygienist shall conduct clearance air sampling no sooner than the earlier of 6 hours from the time the cleanup procedures of wet wiping and HEPA vacuuming are completed, or such time as all surfaces in the work area have dried. If all work area surfaces are dry at the completion of the cleanup procedures, no waiting period shall be required prior to beginning air sampling.

6. (f) The independent industrial hygienist shall use aggressive sampling:

   1. (1) To ensure that any fibers deposited on surfaces within the work area are included in the sample;
   2. (2) For all clearance sampling in schools and school buildings; and
   3. (3) In all areas where uncontaminated wall, ceiling, and floor surfaces in the work area are covered with sheeting.

7. (g) The owner or operator shall ensure that the asbestos abatement entity does not dismantle the containment and worker decontamination system until clearance air sampling demonstrates the presence of no more than 0.010 fibers of length greater than 5 microns per cubic centimeter of air as determined by the following:

   1. (1) Except as provided in (2), below, phase contrast optical microscopy, performed as described in “Asbestos and Other Fibers by PCM: Method 7400, Issue 3”, National Institute of Occupational Safety and Health (NIOSH) Manual of Analytical Methods (NMAM), 5th Edition, June 14, 2019, available as noted in Appendix B; and
   2. (2) For projects at schools subject to AHERA, transmission electron microscopy (TEM) performed as stated in 40 CFR 763, subpart E, appendix A: “Mandatory and Non-mandatory” or as defined and accepted by the National Institute of Standards and Technology (NIST) for TEM accreditation.
8. (h) The industrial hygienist shall submit copies of the clearance air sampling results to the owner or operator, and the department, by mail, hand delivery, or electronic means, within 30 days of the date of the clearance air sampling.

Source. (See Revision Note #1, Revision Note #2, and Revision Note #3 at chapter heading for Env-A 1800) #14104, eff 11-1-24, EXPIRES: 11-1-34