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ASTM D7886 Standard Practice for Asbestos Exposure Assessments for Repetitive Maintenance and Installation Tasks
Information on ASTM D7886 is presented below. If you would rather talk with him about it, call Andy Oberta at (512) 266-1368 or send an e-mail to andyobe@aol.com. (Andy is the ASTM Technical contact for this standard.)
What are asbestos exposure assessments?
In order to determine respiratory protection and other precautions against inhaling asbestos fibers, airborne fiber concentrations are measured with air samples taken while an asbestos-containing material is being disturbed. This process is called an exposure assessment.
Isn’t that what OSHA calls a Negative Exposure Assessment?
OSHA requires exposure assessments for asbestos work and a Negative Exposure Assessment (NEA) is one that shows exposure will not exceed either Permissible Exposure Limit (PEL). With an NEA, an employer can dispense with certain precautions, including respirators and protective clothing, decontamination facilities and medical examinations, and remain in compliance with the OSHA regulations.
How does ASTM D7886 differ from an OSHA exposure assessment?
First, ASTM D7886 is intended for repetitive tasks that are performed frequently at multiple locations. Disturbance of asbestos-containing material is incidental to the work but is not its purpose and small amounts of asbestos-containing material are involved. ASTM D7886 is not intended for use on abatement projects.
Second, ASTM D7886 measures airborne fiber concentrations under controlled conditions in an exposure assessment test, not at an actual job site.
Third, OSHA requires that an NEA show with a “high degree of certainty” that the PELs will not be exceeded. They don’t explain how to do that, nor do they define a “high degree of certainty.” ASTM D7886 does both and includes statistical methods to compare the exposure assessment test results to the exposure criteria.
What do ASTM D7886 and OSHA exposure assessments have in common?
They share three important requirements and two important terms:
• The asbestos-containing material in the exposure assessment test must “closely resemble” those that will be disturbed on the “current job.”
• The work practices in the exposure assessment test must “closely resemble” those to be used on the “current job.”
• The workers who will perform the “current job” must be trained to use the work practices in the exposure assessments test.
The “current job” refers to the tasks that tradesmen and technicians will perform at actual job sites.
Who does the exposure assessment tests?
The exposure assessment tests are done by persons accredited for asbestos work under the EPA Model Accreditation Plan. In some states they may be required to be licensed. The participants include:
• The test conductor who designs and directs the test, takes air samples, does the statistical calculations and prepares the test report. This person will typically be an industrial hygienist or other consultant.
• The test supervisor who constructs and operates the negative pressure enclosure in which the work practice task is performed. This person typically works for an asbestos abatement contractor.
• The test worker who performs the work practice task under the direction of the test conductor. This person also works for an asbestos abatement contractor.
Their qualifications are described further in an Annex to the standard.


How is an exposure assessment test performed?
It begins with the test conductor determining the work practices and asbestos-containing material involved with the “current job.” He then finds a location where a similar asbestos-containing material can be disturbed for purposes of the test. The test supervisor and test worker construct a negative pressure enclosure and establish enough pressure differential to avoid contaminating surrounding spaces.
The test consists of having the test worker do the work practice inside the negative pressure enclosure while the test conductor takes personal air samples with two pumps worn by the test worker. The test is run for 90 or 120 minutes, allowing three or four tests to be run on one day.

Why 90 or 120 minutes and two pumps?
The OSHA PELs are common criteria for exposure assessments. The 8-hr Time-Weighted-Average (TWA) Limit of 0.1 f/cc requires samples taken over an extended period, and the Excursion Limit (EL) of 1.0 f/cc requires samples to be taken over a 30-minute period. In the exposure assessment test one sample cassette is left on for 90 or 120 minutes and the other sample cassette is changed every 30 minutes. If three 90-minute tests are performed in a day there will be three “TWA” samples and nine “EL” samples.
How are the samples analyzed ?
Samples are analyzed by Phase Contrast Microscopy according to NIOSH Method 7400. There is an option in ASTM D7886 to also analyze the filters by Transmission Electron Microscopy according to NIOSH Method 7402.

How are the results reported ?
An eight-hour TWA exposure is calculated from the 90- or 120 - minute samples and the 95% Upper Confidence Limit (UCL) of the 8-hr TWA exposure is also reported. The average of the 30-minute EL samples is calculated as well as the 95% UCL of those samples. The equations for these calculations are given in the standard.
ASTM D7886 defines a Confidence Factor (CF) that is equal to the 95% UCL. If the CF is below the exposure criterion, such as the OSHA PEL, the competent person can be confident that the workers performing the current job have less than a 5% chance of being exposed above the PEL. In the example shown here, the CF is well below the 8-hr TWA exposure limit.

The spreadsheet for the exposure and statistical calculations is not part of the downloadable ASTM D7886 file. CLICK HERE to download the instructions for using the spreadsheet. The instructions have a link to the Excel file.

Who is the competent person?
OSHA defines the competent person as the individual who is responsible for the health and safety of the workers he supervises, and this includes work involving asbestos-containing materials. The competent person makes decisions about respiratory protection and other precautions against exposure to asbestos fibers on the current job, and the results of the exposure assessment test help him make these decisions – with confidence.
How does the competent person certify than the exposure assessment applies to the current job?
ASTM D7886 has a certification form in an appendix that the competent person fills out with the pertinent information, including the test results, description of the asbestos-containing material and work practice, and information specific to the current job. He uses this form to certify that the asbestos-containing material and work practice “closely resemble” those of the exposure assessment test, and that the workers have been trained on the work practice. This form may be copied with attribution to ASTM.
How are workers trained for the task on the current job?
For Class III work, which includes the tasks for which this standard is intended, OSHA leaves the duration of training up to the competent person. It must cover the work practice and take at least four hours, including a hands-on exercise. Some states may require longer training and work in schools requires 16 hours to comply with AHERA.
What are some of the tasks that an exposure assessment can be used for?
ASTM D7886 includes a list of tasks as examples, and my own experience includes numerous tests including drilling and punching holes through floor tile, lifting pieces of floor tile, and drilling holes in asbestos siding, paint and plaster.

Who pays for the exposure assessment test?
The test may be funded in several ways. A building owner with multiple locations may want to have the test conducted and train employees or vendors who work in the buildings. A vendor who performs a repetitive task for multiple clients may want to pay for the tests, or a trade association of building owners or vendors may want to support the effort. The important thing is that the test be designed and conducted to meet the needs of the user.
What are the cost implications of exposure assessments?
The exposure assessment test is an up-front cost that typically includes two days of work by the test conductor, test supervisor and test worker at the test site, plus laboratory charges for sample analysis and follow-up by the test conductor to analyze the results and prepare the report. There will be minimal training expenses for the workers to do the task on the current job. These expenses will be offset by not having to call in an abatement contractor to perform these tasks for charges out of proportion to the work actually done at the job site. A building owner or vendor would not have to incur the expense of putting his workers through a training course that covers work they will never perform, not to mention getting licensed to do that work.
What about annual updates?
ASTM D7886 does not discuss the annual updates that OSHA requires to maintain an NEA in effect. If you have established that exposures are below the PELs, the annual updates can be performed without a negative pressure enclosure and, if you choose to do so, without respiratory protection or certain other exposure controls. You would still use the same asbestos-containing material and work practice, and follow the same sampling, analytical and statistical protocols in ASTM D7886.
How do I get a copy of ASTM D7886?
You can order it on-line and download it as a PDF file at http://www.astm.org/Standards/D7886.htm. The current price is $48, a worthwhile investment in a resource than can help protect your workers in a cost-effective manner.

ASTM D7886 Standard Practice for Asbestos Exposure Assessments for Repetitive Maintenance and Installation Tasks was developed by ASTM Subcommittee D22.07 on Sampling and Analysis of Asbestos. ASTM D7886 is copyrighted by ASTM International, 100 Barr Harbor, West Conshohocken, PA 19428. All rights reserved.
Andrew F. Oberta, MPH, CIH
The Environmental Consultancy
(512) 266-1368
andyobe@aol.com

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