After reviewing the available data on ammonia, carbon monoxide, chlorine, hydrogen chloride, hydrogen cyanide, hydrogen sulfide, nitrogen dioxide, and sulfur dioxide, the subcommittee concludes that the Navy’s proposed SEALs would be protective of the health of personnel in a disabled submarine with the exception of the SEALs for chlorine. In addition, the subcommittee concludes that the SEALs for the gases except chlorine could be set at levels higher than the Navy’s proposed levels and still be protective of the health of crew members in a disabled submarine; eye or respiratory-tract irritation or central-nervous-system effects would not be intolerable or impair performance of specific tasks, including the ability to escape. A comparison of the subcommittee’s recommended SEALs with the Navy’s proposed SEALs is presented in Table 10–1. In addition to the research needs identified for each gas in Chapters 2–9, the subcommittee also has several additional recommendations that are presented in this chapter.

The subcommittee recommends that additional research be conducted on the health effects of mixtures of the irritant gases—ammonia, chlorine, hydrogen chloride, hydrogen sulfide, nitrogen dioxide, sulfur dioxide. The subcommittee also recommends additional studies be conducted on the combined effects of hydrogen cyanide, carbon monoxide, and hydrogen sulfide.

As described in Chapter 1, the Navy has developed instructions for the management of toxic gases in disabled submarines. Those instructions use a Cumulative Exposure Index (CEI) approach, which assumes that the effects of

exposure to the irritant gases—ammonia, chlorine, hydrogen chloride, nitrogen dioxide, and sulfur dioxide—are additive and not synergistic. The subcommittee believes that hydrogen sulfide should be considered an irritant gas and added to the CEI. The subcommittee also believes that a separate CEI should be established for carbon monoxide and hydrogen cyanide because the effects of exposure to these gases maybe additive as well. If the results of research conducted on the health effects from exposures to mixtures of gases show that the effects are not additive, then the CEI approach will have to be modified accordingly.

The effects of environmental conditions (e.g., humidity, temperature, and pressure) found on a disabled submarine on the toxicity of the gases should be studied. Also, because fires on a disabled submarine will generate participate matter, research should be conducted on the effects of particles on the toxicity of the gases.

As noted in Chapter 1, the Navy instructs crew members wearing EABs to remove them each hour, as concentrations of some of the gases should decrease overtime because of contact with the wet surfaces likely to be found in a disabled submarine. That same logic leads the subcommittee to recommend that the concentrations of all gases be determined as frequently as possible.

The subcommittee emphasizes that its recommended SEALs are for normal atmospheric conditions (an atmospheric pressure of 1 and a temperature of 25°C). Values obtained for gas concentrations using Dräeger tubes in a disabled submarine might need to be corrected to an atmospheric pressure of 1 and 25°C. The subcommittee did not find information on the effects of hyperbaric conditions on Dräeger-tube measurements and recommends that research be conducted to determine the effect of increased pressure on Dräeger-tube measurements.

Currently, Dräeger tubes are the only means available on submarines for measuring gas concentrations once the spectrophotometers stop functioning because of power loss. Dräeger tubes have an error rate of about 30% (i.e., the indicated value maybe 30% lower or higher than the actual gas concentration), and a new tube is required for each measurement of an individual gas. The subcommittee recommends that the Navy place high priority on developing a battery-operated instrument for use in submarines to more accurately measure the gases and allow for frequent measurement of the gases in disabled submarines.

U.S. Navy. 1998. Memorandum from N.A. Carlson, Acting Commanding Officer, Naval Submarine Medical Research Laboratory to Officer in Charge, Naval Medical Research Institute Toxicity Detachment. Subject: The Management of Toxic Gases in a Disabled Submarine. March 2, 1998.