Instructions for Statistical Calculations Spreadsheets
ASTM D7886 Practice for Asbestos Exposure Assessments for Repetitive Maintenance and Installation Tasks

Andrew F. Oberta, MPH, CIH
The Environmental Consultancy

NOTE: Use of these spreadsheets presumes that the user has obtained a copy of ASTM D7886 Practice for Asbestos Exposure Assessments for Repetitive Maintenance and Installation Tasks from ASTM International at These spreadsheets are not part of the downloaded file for ASTM D7886, are not an ASTM product and are not copyrighted by ASTM. Neither ASTM International, The Environmental Consultancy or Andrew F. Oberta, MPH, CIH are responsible for any circumstances arising from the use of the spreadsheets.
Review ASTM D7886 with special attention to Section 7. Exposure Calculations.
CLICK HERE to open the file D7886samplecalculations.xls, make a working copy and save the original unchanged.
They calculate the exposures for each test, including the TWA (90 or 120 minute) and EL (30 minute) tests.
They calculate the 8-hr TWA exposure and the 95% UCL of the set of TWA tests, and the average and 95% UCL of the set of EL tests. (In ASTM D7886 the Confidence Factor (CF) is equal to the 95% UCL.)
The spreadsheets are set up for calculating fiber concentrations from samples analyzed by NIOSH Method 7400. They are not set up for calculations based on analysis by NIOSH Method 7402, which is an option in ASTM D7886.

There are three spreadsheets, identified on the tabs at the bottom: 3 - 90 min tests, 4 - 90 min tests and 3 - 120 min tests. Select the sheet corresponding to the test you have conducted and do the following:

NOTE: You can insert one or more columns before Column A or between Columns A and B to add information such as worker identification or description of the test conditions. Do not insert or delete rows in the table.

Sample Number column
Retain the default entries in this column.

Sampling time, min column
The default values of 90, 120 and 30 are entered in this column. When taking the samples, it is important to adhere to these times as closely as possible. If you deviate slightly from these times, enter the actual sampling times in place of the default values.
The No Monitoring time is automatically calculated by the program.

Flow rate, min column
Enter the flow rates measured for the TWA and EL sampling pumps.

Volume, liters column
The volume for each sample will be calculated by the program.

Fibers counted column
Enter the number of fibers counted for each sample from the lab report. (Make sure the report includes this information and not just the fiber concentration in f/cc or the fiber density in f/mm².) Enter the actual number of fibers counted even if it is less than the NIOSH 7400 LOD of 5.5 fibers/100 fields.
Replace the 0.0 default values with the number of fibers counted for each of the three blank filters.

Fields counted column
The default value of 100 has been entered. If less than 100 fields are counted, replace 100 with the actual number.

Fibers/cc column
The program calculates the fiber concentration for each sample, using the entries for sample volume and fibers counted, adjusting for the number of fibers counted on the blank filters. (If less than three blanks are counted the algorithm for this column has to be modified.) If less than 5.5 fibers are counted on a sample, the actual number in the Fibers counted column is used, not the 5.5 fibers/100 fields NIOSH LOD value.

TWA Calculations columns
The TWA concentrations and No Monitoring values are copied automatically from the Fibers/cc column. The 8-hr TWA, Average TWA and 95% UCL (CF) concentrations are calculated by the program using the equations in Section 7 of ASTM D7886.

EL Calculations columns
The Average EL and 95% UCL (CF) concentrations are calculated by the program.

TO OPEN THE FILE D7886samplecalculations.xls CLICK HERE
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