October 19, 2019

October 2019


Recently Withdrawn Methods

OSHA maintains a list of methods that have been withdrawn/replaced.

Organic Vapors [7] Withdrawn (replaced by various NIOSH Methods)
Methyl Alcohol [91] Withdrawn (replaced by OSHA Method 5001)

View the OSHA Withdrawn Methods page for additional information.

NIOSH 7400 Method Update Released

A revision of NIOSH’s method for analysis of asbestos and other fibers by phase-contrast microscopy (PCM) has been added to the NIOSH Manual of Analytical Methods. Dated June 14, 2019, the revised method presents alternative procedures for preparing and mounting asbestos samples on microscope slides for counting fibers under PCM, a technique that renders visible the changes in light waves as they pass through objects. The revised method also explains the optional but recommended use of special slide coverslips intended to improve laboratory microscopists’ accuracy when counting fibers.

The rules governing which entities seen through the microscope should count as asbestos fibers remain unchanged.

Martin Harper, who coauthored the revised method, emphasized that the changes give laboratories the flexibility to choose among combinations of treatments and mounting media.

“There’s been no major change [in the revised method] that would cause folks to have to rush out and make substantial changes to what they’re doing,” Harper said. “There are now choices and clarifications in the method that are intended to be helpful to people and to allow them the leeway to do some things a little differently.”


A PDF of NIOSH method 7400, “Asbestos and Other Fibers by PCM,” is available from the agency’s website. The June 14, 2019, revision of NIOSH 7400 contains editorial corrections not present in an earlier version of the method dated April 29, 2019. NIOSH requests that users of the method ensure that they have downloaded the June 14 version (PDF).

Read the full article on AIHA's website.

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