Measurement and Control of Asbestos Emission

Measurement and Control of Asbestos Emission

Asbestos Emission Control

Measures to control asbestos contamination of the environment have been pursued by both the government and private Individuals. Federal oversight of the problem is centralized in the  OSHA and the Environmental Protection Agency (EPA). OSHA regulates airborne concentrations in the workplace according to the threshold concept. OSHA stands for Occupational Safety and Health Administration.

Measurements above the threshold level are considered harmful; measurements below are judged safe. The current regulation designates two fibers per cubic centimeter (2f/cc) as the threshold. ‘Consideration is currently being given to a more stringent level of 0.5 f/cc.’

Optical microscope analyses used permit identification of only those fibers longer than five microns. Alternative measurement procedures have been proposed.

A threshold level of 30 nanograms/cubic meter has been proposed by Connecticut environmental protection authorities. This mass analysis technique, however, is biased in favor of small fibers and agreement has not yet been reached on the risks associated with small fibers.

Other methods include measurement of asbestos particles (impinger analysis) and small fibers by electron microscope. Each method measures something different, and therefore, they do not correlate well. Alternative measurement procedures have been proposed.

Ultimate revision of the current standard may result in the establishment of a zero-base level.

The National Institute for Occupational Safety and Health has stated that present data is insufficient to set a standard for long-term asbestos exposure other than zero which could preclude the development of malignancies. In fact, recent disclosures indicate that the proposed level of 0.5 f/cc may still be too high.

Scientists have found the risk of respiratory disease to be three times the expected rate for miners exposed to fiber concentration levels of 0.24 f/cc.

Standard Problems

The EPA’s control of ambient asbestos levels is aimed at reducing the danger to the public from the use of asbestos products. No numerical standards have been promulgated because of the difficulty encountered in prescribing a standard with an ample margin of safety.

Asbestos-Emission

The current regulations, as applied to asbestos spraying, require that “materials used to insulate or fireproof buildings, structures, pipes, and conduits shall contain less than  1%  asbestos.

As a result, asbestos insulation is being replaced by fiberglass. Private individuals have also taken steps to control asbestos where a problem had been identified. Yale, UCLA, and a Wyoming elementary school have all taken measures to remove asbestos from their buildings.

Yale found asbestos emissions in their Art and Architecture Building exceeded the 2.0 f/cc limit in some instances. All building users were exposed to a level over that found in the ambient air.

Note: This Article is extracted from an Old Document “The Health Effect of Asbestos Inhalation” published in 1980.

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