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Environmental Air Monitoring for Asbestos

Asbestos is a naturally-occurring mineral known for chemical resistance, thermal stability, and durability. Due to these properties, asbestos was utilized in thousands of consumer products including insulation and construction materials. When asbestos materials are damaged or disturbed, asbestos fibers can be released into the air, causing significant health risks and lung damage in exposed individuals. Asbestos air monitoring is conducted to assess risk and to ensure effective control methods are in place.

Millipore® Aerosol Monitors (or Air Monitors) for industrial asbestos monitoring feature a conductive, carbon-filled, polypropylene cassette to eliminate static electricity and a 50 mm extension cowl to ensure high sample concentration and uniformity. Millipore® Air Monitors meet specifications of the National Institute of Occupational Safety and Health (NIOSH) and other industry-standard methods for airborne asbestos fiber monitoring. In addition to air monitors, we carry a comprehensive portfolio of Millipore® cut disc membrane filters, filter holders, cassettes, and accessories for air monitoring.

NIOSH 7400 - Asbestos and other fibers by PCM

NIOSH 7400 uses phase contrast microscopy to estimate fiber concentrations in air. The method is primarily used for estimating asbestos concentrations, though phase contrast microscopy (PCM) does not differentiate between asbestos and other fibers. In this method, samples are collected using a 25 mm air monitoring cassette equipped with a 50 mm electrically-conductive cowl and a 0.45- to 1.2-µm cellulose ester filter.

Analytical method:

  • Phase contrast microscopy

Compatible filters and other materials for NIOSH 7400:

  • 25 mm cassette with 50 mm conductive cowl, 0.8 µm mixed cellulose ester (MCE) membrane (MAWP025AC)
  • 0.8 µm MCE cut disc membranes (AAWP02500; AABG02500)
  • Forceps for membrane handling (XX6200006P)

Link to NIOSH 7400 method

NIOSH 7402 – Asbestos Fiber Identification and Quantification by Transmission Electron Microscopy

NIOSH 7402 uses transmission electron microscopy (TEM) to qualify and quantify asbestos fibers found in the air. This technique provides complimentary results to fiber counts determined by NIOSH 7400, and provides more accurate asbestos fiber counts as non-asbestos particles are eliminated using this method. Samples are collected using a 25 mm air monitoring cassette equipped with a 50 mm electrically-conductive cowl and a mixed cellulose ester (MCE) membrane filter. After collection, samples are processed to collapse the filter, creating a non-grainy background for easier fiber counting and identification by transmission electron microscopy. Fibers with a diameter <0.25 µm will not be detected by this method.

Analytical method:

  • Transmission electron microscopy (TEM)

Compatible materials for NIOSH 7402:

Link to NIOSH 7402 method

NIOSH 9000 - Asbestos, Chrysotile by XRD

This method uses X-ray powder diffraction to perform analysis of percent chrysotile asbestos in bulk samples. Note the precaution that since asbestos is a human carcinogen, it should be handled in a hood. NIOSH methods 7402 (Asbestos by Transmission Electron Microscopy) and 9002 (Asbestos by Polarized Light Microscopy) are also useful for positive identification of asbestos. The method calls for a 25 mm, 0.45 µm silver membrane and a 37 mm, 1.0 µm polycarbonate filter.

Analytical method:

  • X-Ray powder diffraction

Compatible filters and other materials for NIOSH 9000:

Link to NIOSH 9000 method

OSHA 160 - Asbestos in Air

OSHA 160 uses phase contrast microscopy (PCM) to determine airborne asbestos concentrations. Fibers ≥ 5 µm in length and at least a 3:1 aspect ratio are counted. In this method, a known volume of air is drawn through a 25 mm diameter cassette containing a mixed cellulose ester filter. The cassette must be equipped with an electrically conductive 50 mm extension cowl. The sampling time and rate are chosen to result in a fiber density between 100 to 1,300 fibers/mm2 on the filter. A portion of the sample filter is then cleared and prepared for asbestos fiber counting by phase contrast microscopy at 400X.

Analytical method:

  • Phase contrast microscopy

Compatible filters and other materials for OSHA 160:

Link to OSHA 160 method

Norme NF X 43-269 - Qualité de l'air (France)

NF X 43-269 concerns the monitoring of dust levels, the conditions under which occupational exposure to asbestos fibers is monitored, compliance with the limit values established for exposure, and the accreditation qualifications for any organization or institution performing the testing and analyzing the measurements.

This method, effective May 30th, 2018, replaces the previous method XP X 43-269 (2012). It requires the use of a 37-mm electrically conductive three- or four-piece cassette. The method employs a 0.45 to 1.2 µm MCE membrane filter as well as a polycarbonate filter for processing and analysis.

Analytical methods:

  • Phase contrast microscopy (MOCP), scanning electron microscopy (MEBA), or transmission electron microscopy (META)

Compatible filters and other materials for NF X 43-269:

Australia - Guidance note on the membrane filter method for estimating airborne asbestos dust

The Australian Guidance note respecting airborne asbestos dust for occupational environments has similar requirements to the OSHA 160 and NIOSH 7402 methods. The regulation specifies a 0.8 µm MCE or cellulose membrane of preferably 25 mm diameter (although other diameters can be used, as long as the effective filter diameter is no less than 9.5 mm with a 13 mm filter) in addition to an open-faced 25 mm air monitoring cassette equipped with a 50 mm electrically-conductive cowl. The membrane specification, however, has been updated to require a gridded membrane for enhanced particle counting purposes.

Analytical method:

  • Phase contrast microscopy

Compatible filters and other materials:

  • 0.8 µm gridded MCE membrane, 25 mm diameter (AABG02500)
  • 25 mm cassette with 50 mm conductive cowl with removable filter (MAWP025AC)
  • Forceps for membrane handling (XX6200006P)

Link to guidance note

Products for airborne asbestos monitoring

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