Test Method 435 - Determination of Asbestos Content of Serpentine Aggregate

This page last reviewed June 17, 2016



Test Method 435 (M435), entitled "Determination of Asbestos Content of Serpentine Aggregate," was adopted by the Air Resources Board (ARB or Board) in April 1990 in support of the Asbestos Airborne Toxic Control Measure (ATCM) for Surfacing Applications.  This ATCM aims to reduce public exposure to naturally occurring asbestos (NOA) by limiting the asbestos content of surfacing materials.  The Asbestos ATCM for Construction, Grading, Quarrying, and Surface Mining Operations, adopted in 2001 to minimize generating asbestos-containing dust during those activities, also references M435 as an approved test to measure the asbestos content of bulk materials.

ARB staff conducted a M435 interlaboratory study (ILS) which identified variability in equipment used and procedures followed among the participating laboratories and demonstrated that these differences can significantly affect the reported asbestos content of rock and soil samples.  In response to these ILS findings, ARB staff conducted workshops, sent out surveys, fielded numerous comments, and conducted method testing to seek ways to improve the accuracy and repeatability of M435 results.

In lieu of making formal regulatory revisions to M435, staff is writing a “good practices” guidance document that should help both field and laboratory personnel obtain more accurate and repeatable asbestos content determinations using M435.  Staff has posted a working draft of the Test Method 435 Field Sampling and Laboratory Practices Implementation Guidance Document which is intended to be used in conjunction with M435.

Comments on the working draft will be accepted during the 45-day comment period (June 17 through August 1, 2016) and can be sent via email to Rebecca.Neumann@arb.ca.gov or by mail to:

Air Resources Board
Monitoring and Laboratory Division
P.O. Box 2815, Sacramento, CA 95812
Attention: Rebecca Neumann



Working Draft Test Method 435 Guidance Document and Appendixes - June 17, 2016



Association of Environmental & Engineering Geologists NOA Symposium - December 18, 2014




Public Workshop - June 10, 2008




Public Workshop - January 24, 2008




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For more information about the M435 revision activities, please contact Patrick Rainey at (916) 327-4756 or Rebecca Neumann at (916) 324-1145.

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