Run Silent, Run Clean

By James Schultz

For months on end, a nuclear submariner’s world consists of time spent in an enclosed metal tube, often hundreds of feet below the ocean’s surface. Underseas, the only breezes are those that gust from ventilation fans circulating and recirculating the same air. Fresh air, and a sight of land and sky, must wait for a port of call or deployment’s end.

Because senior Navy officials know full well the health risks of crowding sailors into a self-contained environment, a submarine’s atmosphere-control program adheres to strict standards. Submariners are prohibited from bringing on board a variety of common consumer products, such as deodorants and other aerosol products, which contain injurious chemicals that can gradually leach into a sub’s air and thence into human lungs.

Nevertheless, because the air inside a submarine is continually recycled, and despite the best efforts of scrubbers and filters, it may contain trace amounts of contaminants. Harmful substances exude from human and microbial metabolism, disperse in gaseous form from sub machinery and hardware, and emanate in minute aerosols produced by lubricating oils, hydraulic fluids and other materials necessary to operations. Among the latter toxins are ozone from electrical and electronic components, formaldehyde from paints, adhesives and textiles, and acrolein, an organic pollutant resulting from incomplete combustion, such as that produced by deep fryers.

In an effort to identify the extent of air degradation, Old Dominion University researchers are working on a fleet-wide project as part of the Naval Submarine Medical Research Laboratory’s Submarine Atmosphere Health Assessment Program. The program aims to investigate the total spectrum of contaminants in the atmosphere of the Navy’s contingent of nuclear submarines and determine the extent of possible long-term health effects on sailors.

“You have people living in a closed environment, breathing the same air 24 hours a day for weeks on end,” says research team leader William Luttrell, an assistant professor of industrial hygiene. “There are low concentrations of airborne contaminants. Some mixtures of these contaminants may be toxic. Some mixtures may not be toxic. Our job is to establish a baseline so potential hazards don’t escalate into a major health issue.”

Setting The Baseline

To gauge the extent of potential contamination, Old Dominion researchers must first establish the extent of exposure. The task is made more difficult by data collected in previous studies that show discrepancies among specimens. Some tested areas appear unusually active; yet, when re-tested, contaminant levels drop significantly. The lack of correlation may be as simple as location. Aft sections, where engine machinery is clustered, may give off greater concentrations of polluting substances. The air in forward sections may not be as sullied. Or perhaps the sampling gear has not functioned properly. Or perhaps atmosphere-control systems work more efficiently in certain locations and less so in others.

To obtain accurate measurements, the University team samples 10 different areas within each sub, over a 28-day period. In one section, active sampling takes place, conducted by means of cell-phone-size “pocket pumps” that pull air through sampling filters or small absorbent tubes. The other nine areas are sampled exclusively by passive monitors, in the form of quarter-size monitors hung unobtrusively from stanchions and supports. Active and passive samples are then compared, to validate the outcomes from the passive-sampling technology. Any anomalous feedback from any of the roughly 100 passive monitors throughout the submarine can be checked against the readings made by the active equipment.

The sampling apparatus is designed for ease of operation and to minimize interference with normal submarine activity. Crewmen have minimal responsibility for the sampling sensors, which are collected by Old Dominion health scientists at the end of the experimental period.

Thus far, the Old Dominion team has taken samples from seven submarines: three attack subs home-ported in Norfolk and four in Groton, Conn. Samples are sent for analysis to laboratories in Connecticut, California and Ohio. When results are compiled from several more sub-air studies, the Old Dominion team will analyze and publish them later in this year.

Breathing Cleaner Air?

Even with the blessing of Chief of Naval Operations, the study has been difficult to conduct. At any one time, roughly one-third of the submarine force is available, another third is deployed at sea, and the remaining third is undergoing routine maintenance.

“The science is easy. The hard part is logistical,” says Larry McFarland, a U.S. Navy lieutenant commander working on the submarine study and an Old Dominion graduate student in environmental health and industrial hygiene. “The greatest challenge is actually getting on the submarine. There are security issues, operational constraints, and there are fewer submarines to choose from because of downsizing.”

When the Old Dominion researchers conclude their investigations, they will prepare a written report for the Naval Submarine Medical Research Laboratory to assist in the development of a definitive air-sampling protocol for all Navy submarines. Using information collected from these studies, design engineers may propose modifications to minimize or eliminate altogether even small contaminant amounts, with the ultimate goal of reducing to zero the threat from on-board pollutants.

“Long-term chronic exposure to toxins, even at very low levels that are normally not considered to be hazardous, could lead to health problems,” says team leader Luttrell. “Multiple chemical interactions can also be damaging. We’re focusing on agents that even in very small quantities could be harmful over a long period of time.”

The results of the research could literally end up in space. The same air recirculating/recycling issues that crop up in submarines do so in other closed biospheres, such as human-carrying spacecraft and orbital space stations. NASA has already expressed interest in the Old Dominion research. Information derived from the University’s submarine air-quality studies may one day be used by NASA and others to devise protocols for extraplanetary living quarters and to design robust and redundant environmental controls.