DECOMPRESSION SICKNESS AND TUNNEL WORKERS

Courtesy of Port of Miami

NIOSH-developed Edel-Kindwall Decompression Tables

Four different tables were developed:

• G3A Air Interim Decompression Tables [PDF - 17,353 KB]
  Utilized for pressures in the range from 14 psi to 50 psi to be used at altitudes no greater than 800 – 1000 feet.
• G3A1 Air Interim Decompression back-up Tables for G-3A where environmental or individual conditions warrant [PDF - 17,353 KB]
  Serves as a backup for Table G3A where environmental or individual conditions warrant, based on the most severe conditions which might be anticipated and under which such conditions should produce a decompression sickness incidence that is significantly improved over current practice.
• G3B1 Oxygen Interim Decompression Tables. [PDF - 17,353 KB]
  Note that these should not be used unless the contractor is willing to obtain special training for the personnel involved and properly maintain the required oxygen equipment.
• G3C Air Saturation Interim Decompression Table [PDF - 17,353 KB]
  These should be used when operational needs or emergencies required workers to remain under hyperbaric conditions for more than 8 hours.

The Tables report includes a history of decompression tables. The report also provides background on the NIOSH Edel-Kindwall tables development. Important assumptions are described on page 23/66. Instructions are provided on page 27/66.

In 1985, these tables were provided to OSHA. They have been used for variances in a number of cases. Given the study showing that decompression sickness can occur using the OSHA tables, and the increase in deep tunneling operations, NIOSH is posting these tables to make them more available to employers and safety and health professionals.

Additional decompression tables exist. Many of the tables were developed for specific purposes, such as the U.S. Navy Tables. Other tables have been developed by countries and used in those countries. The following links contain information on those Tables.

1. HSE Reports: A guide to the Work in Compressed Air Regulations 1996 [PDF - 943 KB]
2. National Oceanic and Atmospheric Administration (NOAA) Diving Program page with U.S. Navy tables
3. French Tables 1992 [PDF - 246 KB]

Limitations of the NIOSH-developed Decompression Tables

• The NIOSH tables do not address pressures greater than 50 psi. Higher pressures are common among underground construction jobs. Some jobs use tables from other countries such as France or Germany that address higher pressures.
• The NIOSH tables do not address the use of technical gas mixtures. Divers and technical gas mixtures are used for underground construction operations. Commercial divers use Trimix, which is a mixture of oxygen, nitrogen, and helium, or other mixtures. Tables for these gas mixtures exist, but are usually trademarked.