How Off Gassing Keeps Divers, Submariners Safe From Toxin Releasing Materials

Everyone knows that new car smell - the chemical odor wafting off the new plastics, fabrics and other materials in a vehicle's interior. Those smells are caused by a chemical process known as off-gassing, which is the release of various chemicals from the materials into the atmosphere. While some may like that smell, it's quite toxic.

Unlike cars, where you can get out whenever you want, that's not possible in deep submergence systems like submarines, which are often deployed for up to 120 days at a time without coming up for fresh air.

To keep divers and submariners safe from toxic fumes, the Navy runs off-gas testing as part of a rigorous authorization process for any equipment and materials that personnel might need below the surface.

The off-gas sampling facility at the Naval Undersea Warfare Center in Keyport, Washington, is one of three Navy locations accredited to perform off-gassing testing for deep submergence systems.

Keyport's facility works specifically with Special Operations Command. Their focus is strictly on non-metallic materials such as wetsuits, hoses, electrical cables and cameras that are taken inside submarines and used by Navy SEALs and other special operators. In a Virginia-class submarine, for example, special operations divers deploy from a lockout trunk, which is a hard tank that floods and deposits the diver and any equipment directly into an undersea environment.

Dan Seacrist, Keyport's off-gassing facility manager, explained how the toxins from new items affect divers and submariners differently than people who are in contact with them at surface level.

"OSHA [Occupational Health and Safety Administration] requirements were designed to where a person in a manufacturing facility would be exposed to [an item] for eight hours, and then he would be not exposed to it for 16 hours … an unload period," Seacrist said. "The people in the submarine never get an unload period. …. It's 24/7, literally, that your body is absorbing these toxins."

When Special Operations Command requests testing on a piece of clothing or equipment, such as a new underwater breathing apparatus, it will provide the Keyport facility with safety data sheets detailing what chemicals were used to make the item and what the acceptable limit is for of each toxin. Those limits are set by the Navy Bureau of Medicine and Surgery's undersea medical experts.

"What we need to know is how many fumes and what kind of fumes are coming off the materials … to determine which chemicals are toxic to the body," Seacrist said. Common toxic chemicals they find in tested materials include formaldehyde, mercury, ammonia, chlorine and butyl-cellosolve.

Baking Off Smells

A lot of materials come into the Keyport facility with a smell, such as clothing that's been in packaging for months and hasn't had a chance to breathe. Before technicians can test those items in pressurization chambers, they're cured to get the smell out.

"We let [the item] ventilate with the clean, fresh air. After 24 hours, we smell it again. We do that three times - so, 72 hours," Seacrist said. "If it still smells, then we know that we're going to need more aggressive curing to accelerate it."

The next step is to blow hot air onto the items in an enclosed ventilation cabinet to help release the toxic vapors. If that's not enough, they use a convection oven to essentially bake the material at a low temperature for an extended period. That process is also run three times. If the item still smells afterward, a vacuum oven is used to pull the toxins out.

Seacrist said they may cure and test one single item or an entire swath of material. For example, if a freshly produced wetsuit smells, that means it's off-gassing. The facility might then ask to cure the entire roll of material from which the suit was made.

Seacrist said it's not just new materials they run tests on; they'll process older materials, too, because they can change over time.

"It's like headlights on your car becoming yellow," he used as an example. "What chemical properties are causing it to turn yellow, and what happens after that? We always qualify the new materials, but then we also sometimes look at the degradation over time."

The Off-Gassing Process

After curing is complete and the smells are gone, items are sent to pressurization chambers to further test for toxic vapor levels. Items that don't have a smell go straight into these chambers.

The Keyport facility uses various chamber sizes, depending on the amount of material that's being tested. One chamber that Seacrist's team uses is large enough to fit small unmanned underwater vehicles.

"It's been painted with new paints, which are non-metallics but go through our curing process," Seacrist explained of a UUV they tested. "The antennas and flight control surfaces are 3D printed now, and the lubricants that they've used all are things that could off-gas or create a toxic environment."

The chamber gets warmed to a specific temperature akin to what the material might be exposed to during transit during the warmest part of the year. Then the team tests the material at different depths.

"If it's a painted surface or hard material, then you don't need to take it deep to understand what the chemical release … [is] going to be," Seacrist said. "If it's something like your jacket or a wetsuit, you would want to compress it deep and then let it relax as it comes to the surface. Then the fumes breathe out of it."

Testing at various depths is critical.

"With each breath of air that a diver takes at depth [33 feet below], he's inhaling twice as much [air]," Seacrist explained. "So now the vapors, or the toxins he's being exposed to, are twice as much at 33 feet - three times as much at 60 feet, and it keeps going."

They don't use regular air inside the chambers, either. Instead, a certified gas called "zero gas" - composed of 79% nitrogen and 21% oxygen - is used. Seacrist said it's similar to the mixed gas in divers' SCUBA tanks. It's used for testing so there's no chance that the air inside the chamber is contaminated with environmental hazards, such as forest fire smoke.

Seacrist said running one chamber test can take three days because it takes time to reach and sit at certain pressurized depths. Samples are taken at depth in a two-hour span, then again after the items are slowly brought back to surface, where they sit for another 24 hours.

The air samples are pumped from the chamber into various test tubes, some of which change color. Sorbent test tubes have charcoal created from walnut shells, which are saturated with a chemical that will bind with and absorb toxins.

From there, the samples are submitted to accredited industrial hygiene labs for analysis. Those labs ship their final reports to the Naval Systems Engineering & Logistics Directorate, which decides whether or not the material is acceptable and can be taken onboard a deep submergence vessel.

A Focus on Safety

The deep submergence research program began around 1963 when Adm. Hyman G. Rickover - the father of the nuclear Navy - authorized an investigation into why the nuclear-powered attack submarine USS Thresher sank during deep-diving tests off the Massachusetts coast in April 1963. The disaster killed all 129 crew members onboard.

"At that time, there was no certification process for smaller deep submergence vehicles," Seacrist explained. "So, the Navy created a deep submergence research group qualification and certification process for deep-diving vehicles."

Seacrist was a Special Operations diver for 22 years. He's very aware of how the curing and off-gassing process can protect divers from toxins that cause various issues such as lymphoma, kidney disease and other ailments of the endocrine system.

"There would certainly be long-term health effects that we would see, that the [Department of] Veterans [Affairs] would have to deal with later on," he said of someone who was affected by the toxic gases. "It's not like it's going to make your eyes water and you're going to start coughing. … It's something that's going to show up in your body eight to 10 years later."

Having been a military diver, Seacrist said he enjoys being able to pay it forward to the men and women who have followed in his footsteps.

"There was somebody who was watching my back from the civilian side [when I was a diver] … so now I'm that guy," he said. "I like taking care of the young guys who are out there working for God and country, doing what we never want to know. I'm glad there's somebody doing it."

The Navy Experimental Diving Unit in Panama City, Florida, and the Naval Surface Warfare Center Crane Division in Indiana, are also accredited to perform off-gas testing, as are three commercial companies contracted by the Navy. Depending on what the item is, Naval Sea Systems Command officials will determine what facility's chambers will be used.