A study released in 2014 examines potential airborne asbestos exposure of workers using asbestos-containing gaskets and packing. Amy K. Madl et al., Airborne Asbestos Exposures Associated with Gasket and Packing Replacement: A Simulation Study and Meta-Analysis, 69 REGULATORY TOXICOLOGY & PHARMACOLOGY 304 (2014). The authors simulated historical asbestos exposure using vintage valves (manufactured prior to the 1980’s) of different sizes (nine globe and one gate), which were blasted with abrasive material prior to testing to remove possible external debris. Retired mechanics performed a complete valve overhaul, including removal and installation of asbestos-containing gaskets or packing, inside an enclosed room. In three scenarios a new gasket was also fabricated.

The study assessed potential airborne asbestos fiber content during valve overhaul and post-valve cleanup, as well as when mechanics’ coveralls were shaken and folded at the end of each procedure. The authors collected ambient air samples, bystander and remote area samples, personal samples from the mechanics’, as well as an assistant’s lapel. Id.at 305. The room was also ventilated at the end of each procedure, and background samples were collected before the next event.

The authors calculated a possible 8-hour Time Weighted Average asbestos exposure of 0.002-0.010 f/cc for the mechanics. (This estimate was based on performing 1-3 gasket and/or packing tasks per day for a duration of 30-60 minutes per task.)  This is one-fiftieth to one-tenth below the current OSHA Permissible Exposure Limit of 0.1 f/cc.

Based on the results of this study and a meta-analysis of other data, the authors concluded that, even in the event that workers might be exposed to asbestos-containing gaskets and packing, the concentrations were below both historical and current occupational exposure limits. Id. at 318.