Fire Dampers

Asbestos in Fire Damper Products

Fire dampers are devices used to prevent the spread of fire through open areas of a building, such as air ducts. The dampers are made from fire-resistant materials designed in such a way as to allow air to pass through the duct but block the spread of flames. Most frequently, asbestos fire dampers were employed in HVAC systems, specifically in the ductwork where it penetrates a fire-resistant floor or wall. A fire damper may be "static" (stationary) or "dynamic" (movable). It is often installed with a smoke damper that serves to prevent the movement of smoke from the fire area to other parts of a structure.

The most common type of asbestos used in asbestos fire dampers for HVAC systems was chrysotile, or white asbestos. Building products and materials containing this form of asbestos made up about 97% of the market during the first eight decades of the 20th century. Relatively soft, chrysotile fibers are nonetheless abrasive when they come in contact with lung tissue, causing a build-up of scar tissue that ultimately reduces lung capacity. This condition is known as asbestosis, and accounts for the majority of asbestos disease cases. In addition, chrysotile exposure can result in pleural plaques, a hardening of lung tissue, and has been implicated in a number of auto-immune diseases.

Fire dampers manufactured in the United States no longer use asbestos, as most uses of asbestos were banned in the late 1970s. However, many older buildings may still have asbestos-based fire dampers installed, and building materials imported from other countries with weaker laws surrounding asbestos use could also be contaminated.

Hazards Associated with Fire Damper Products

When intact and undamaged, asbestos fire dampers pose relatively little health risk, as the asbestos material within the damper is contained and the fibers do not enter the air. When these dampers are damaged in a fire, however, or when they become worn with age and use, the asbestos material can become “friable” and fibers can come loose. These loose fibers can then be inhaled, leading to the development of very serious diseases such as asbestosis and mesothelioma. People living or working in buildings with damaged or old fire dampers may be inhaling asbestos fibers. In addition, there is a high risk of asbestos exposure to maintenance and repair workers who deal with old and worn asbestos fire dampers, as well as to demolition workers who tear down buildings that contain this older fire-abatement technology.

Sources

Bowker, Michael. Fatal Deception: The Untold Story of Asbestos (New York: Touchstone, 2003).

Underwriters Laboratories. "Dampers".
(http://www.ul.com/global/eng/pages/offerings/perspectives/regulator/electrical/additionalresources/dampers/). Retrieved 19 January 2011.