Tuesday, July 6, 2010

Permissible Exposure Limits—Are You Being Exposed to Unsafe Levels of Mercury Vapor?

The Federal Occupational Health and Safety Administration (OSHA) set a mercury permissible exposure limit (PEL) of 0.1 mg/m3 (8-hr time-weighted average [TWA]).1 Some state OSHA programs regulate a stricter mercury vapor limit of 0.05 mg/m3 (8-hr TWA). Additionally, the American Conference of Governmental Industrial Hygienists (ACGIH) recommends an a guideline of 0.025 mg/m3; this is the same value regulated by California OSHA.2

One broken 48-inch fluorescent lamp in a small room or vehicle can release enough mercury vapor to exceed the Federal OSHA PEL. Mercury vapor concentrations could exceed occupational exposure levels when working with or near broken bulbs, especially when multiple bulbs are stored or shipped in bulk to recycling facilities. Based on measurements of mercury vapor from single broken fluorescent bulbs, there is a need for additional research to quantify emissions from various types of packaging. The results indicate that emissions from packages not designed to contain mercury vapor represent a real health and safety concern to those involved in its storage, transport and disposal, as well as a legal hazard for any businesses that do not adhere to these stipulations. Recent research has shown that only one current package design which includes a vapor resistant and zip seal bag has proven effective in containing mercury vapor.

1. Occupational Health and Safety Standards: Air Contaminants. CFR, Part 1910.1000, Title 29, 2007.
2. Documentation of the Threshold Limit Values and Biological Exposure Indices, 7th ed.; National Institute for Occupational Safety and Health: Cincinnati, OH, 2001.

Lisa Brosseau, ScD, CIH
Associate Professor
University of Minnesota School of Public Health, Division of Environmental Health Sciences

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