Updated information sought to protect tunnel workers

Construction workers in tunnels are at risk of decompression sickness such as the bends. Without proper preventive measures, these workers may face a variety of health problems, including stroke and paralysis.

The decompression tables used to decrease pressure on the workers are outdated, according to government researchers. They are seeking input to update the procedures used to protect workers.

High-pressure tunneling operations used for some underground infrastructure projects involve compressed air and elevated pressure work sites. "This hyperbaric environment created by ambient pressure and compressed air effects exposed caisson and tunnel workers to the risks of decompression sickness such as the 'bends,'" according to a request for information from the National Institutes for Occupational Safety and Health. "In order to prevent DCS, workers in higher hyperbaric environments must be safely brought back to the non-work environmental ambient pressure -- decompressed -- in decompression areas."

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Workers not decompressed safely may develop the following health ailments:

Joint pain.
Lytic lesions of bones.
Cutaneous disorders.
Spinal cord and brain disorders.
Cardiopulmonary disorders, arterial gas embolism.

The decompression tables enforced by OSHA were developed in 1971 but are "considered inadequate for 'efficiently eliminating nitrogen from the body' at pressures in excess of 36.5 pounds per square inch," according to NIOSH. Tables developed in 1981, the Edel-Kindwall tables, are considered more protective of worker health but are considered inadequate for dealing with pressures greater than 50 psi.

"Many modern projects using Tunnel Boring Machines involve pressures greater than 50 psi," NIOSH says. "There is a need for up-to-date decompression tables."

The agency is seeking information on the types of projects where the Edel-Kindwall tables have been used, reports and findings on the use of the tables, including possible health effects in workers decompressed with data from them, control measures such as personal protective equipment in use where decompression is required, and alternative tables and approaches being used to protect tunneling workers from higher pressures greater than 50 psi.

NIOSH is accepting public comments through March 29. Comments may be submitted on the federal rulemaking portal at www.regulations.gov.

Read more at the WorkersComp Forum homepage.

February 4, 2013

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