The Hidden Hazards of Air Bags

September/October 2014

Recyclers worry about potential explosive and environmental hazards from air bags in end-of-life vehicles, but there’s no consensus on the best way to minimize the risk.

By Diana Mota

Frontal air bags saved 25,782 lives between 1987 and 2008, according to the National Highway Traffic Safety Administration (Washington, D.C.). Commercial air bags first appeared in cars in the late 1980s, and since model year 1999, all new automobiles and light trucks sold in the United States must have both driver and passenger frontal air bags. In addition to those, vehicles today could have other frontal air bags as well as several side-torso, curtain, knee, or seat-back systems for drivers and passengers, says Tony Smith, one of ISRI’s safety outreach managers. The number and type of air bags vary from vehicle model to model and year to year, says Tamara Deiro, director of safety for SA Recycling (Anaheim, Calif.)—some cars can have 10 or more.

In a crash, the point and speed of impact determine which air bag or bags will deploy, says Douglas Campbell, president of the Automotive Safety Council (Lexington, Ky.). Not all end-of-life vehicles have been in a crash, however, and even those that have are likely to have several air bags still intact when they reach the auto dismantler or shredder yard. Those same air bags that can help save lives on the road can put lives at risk in a recycling facility, says Peter Byrne, founder and president of Crashboxx Telematics (Fort Collins, Colo.), which has developed a system to deploy air bags inside ELVs.

SA Recycling learned firsthand about some of the dangers on Jan. 23, 2013. A worker on the picking line at its Phoenix shredder noticed a smoking and sparking item on the belt that resembled a “pipe bomb,” Deiro recalls. He raised his arm to warn a co-worker, who attempted to reach for the item just as it exploded. The first worker ended up with a 3-inch by 4-inch piece of metal shrapnel embedded in his side, she says. Fortunately, “because it was so hot, it actually cauterized the area, so he didn’t have excessive bleeding.” The co-worker momentarily experienced ringing in his ears and a loss of vision, according to witness statements. An investigation revealed that the item that exploded was a cylinder-style air-bag canister, Deiro says.

In addition to their explosion risks, undeployed air bags in ELVs can expose workers to hazardous chemicals. ReMA called attention to these risks almost 20 years ago in an early 1990s policy statement. Since then, auto and air-bag manufacturers have stopped using the chemical that caused the greatest health exposure and environmental concerns, but vehicles with that chemical remain on the road. No federal regulation or industry standard specifies the best practices for handling air bags in ELVs to minimize these risks, and processors face complicating factors such as inconsistent and unclear state regulations; variations in air-bag design, contents, and placement in vehicles; and the condition of vehicles that arrive in their yards for recycling.

Air Bags 101

An air-bag module typically consists of four parts: a thermoplastic cover, which opens as the cushion inflates; the thin nylon or polyester bag; the aluminum, steel, or stainless steel inflator canister; and the steel, plastic, or textile housing, which stores the bag and inflator. The inflator contains a chemical trigger (also called the generant) that, when activated, produces nitrogen gas to fill the bag, says Burke Nelson, environmental, health, and safety supervisor of air-bag manufacturer Autoliv’s Promontory Airbag Recovery Center (Promontory, Utah), which specializes in the deactivation and recovery of air-bag components. The industry has begun using more steel in the canisters, Nelson says.

Inflation systems vary by manufacturer as well as by air-bag type, explains Tom Hajkus, communications manager for Autoliv (Auburn Hills, Mich.). “We build [them] to automobile manufacturers’ specifications.” The air-bag module in the steering-wheel assembly—about the size of a fist—most likely contains a pyrotechnic device that creates the chemical reaction, Hajkus says. Most other air bags use 100-percent compressed gas or are a hybrid of compressed air and a small amount of generant, stored in a tubular canister that can vary in size, he says. The units with compressed gas “carry a real risk of injury,” says Byrne, a former director of sales, marketing, and application engineering for Livonia, Mich.-based TRW Automotive Holdings Corp., a U.S. manufacturer of air bags. Hybrid inflators store gas at about 5,000 pounds per square inch, he explains—“It’s very, very high pressure.” The inflation system operates like a solid rocket booster, he says. The bag bursts from its storage area at up to 200 miles an hour. In other words, an air bag is an explosive device, Smith says. The inflator—either pressurized, with propellant, or both—is the only piece of an air-bag system recyclers need to worry about, Nelson says. As Claiborne Thornton, president of Industrial Environmental Consultants (Nashville, Tenn.), puts it, “I don’t know of any other way to get rid of that explosive agent other than to blow it up.”

Because they contain reactive and explosive materials, the Federal Aviation Administration and the U.S. Department of Transportation (both in Washington, D.C.) as well as several states classify undeployed air bags in ELVs as hazardous materials, says Peter Zaidel, environmental and safety product director of KPA Services (Lafayette, Colo.), a provider of environmental, safety, and other services for the automotive industry. After a bag deploys in a vehicle, most states no longer classify it as hazardous, Campbell says. “Once they’re deployed, they’re just like any other piece of scrap metal.” But devices that appear deployed might only be partially deployed, Byrne cautions. Likewise, a module that appears intact could have damage, Nelson says. “You can’t tell by just looking at it.” Always assume modules are active “until you can be certain they are fully deployed,” Byrne says. “Many inflators have dual stages, and it is quite possible that only one stage has deployed, giving the impression the inflator/canister is inert. However, it may still have an active, uncombusted stage in place.”

Recyclers’ Concerns

In many cases, air bags remain inside vehicles when they go into the shredder, Smith says. The bags often deploy in the shredder box, which contains the explosion, Deiro says. But shredding doesn’t guarantee the air bags will detonate, points out Joel Denbo, chief manager of operations for Tennessee Valley Recycling (Decatur, Ala.). He recalls only one incident at his facility in which a canister detonated outside the shredder, however. “It exploded in the eddy-current [system]. All it did was make a big kaboom and scare everybody.” The canisters can pass through the shredder unscratched, Nelson says. Or they can separate in the shredder, and parts such as the pressurized canisters, or inflators, can slip through holes in the shredder grate and onto conveyor belts, Deiro says.

Previously, undetonated canisters went into the nonferrous stream, where they sometimes injured workers or damaged equipment at secondary aluminum smelters. As the number of steel canisters increases, some make it, undeployed, into the ferrous stream, where they are more difficult to see, Denbo says. Ideally, downstream separation equipment will remove them prior to their coming into contact with workers, Smith says, though some risk remains as long as they are undetonated. A damaged, undeployed inflator could explode, throwing shrapnel or debris in any direction, Campbell says. Or it could act like a missile and shoot through the air as “it releases high-pressure gas,” Byrne says. One previously shot off of SA Recycling’s Anaheim picking belt, traveling about 300 feet, Deiro says. “We [were] lucky no one got hurt.” Byrne agrees. “This is the real danger to people in end-of-life [vehicle] and recycling fields. That’s deadly dangerous. On a scale of one to 10, that’s a 10.” Employees could suffer mechanical force injuries, serious risk to life and limb, hearing damage, and thermal burns, he says. As a result of the incident, SA Recycling enclosed its shredder picking areas with rubber curtains and equipment aprons, Deiro says. After the incident in Arizona, the company also purchased cut-, puncture-, and impact-resistant safety aprons and face shields for workers to wear on the lines to protect their torsos and faces, along with other personal protective equipment.

One safety professional at a recent ReMA Safety and Environmental Council meeting recalled air-bag systems exploding after workers placed them on a roof for drying; another told how a device slipped through a screening process and ended up in an oven as part of a material sampling process. The explosion blew the oven door off, but, fortunately, no one was injured, he said. Greg O’Brien, director of health, safety, environmental, and site-risk management for Autoliv, points out that if a partially shredded air-bag canister releases loose generant, that material is not an explosion risk on its own. “The material used is very hard to get started out by itself, and if not contained, it does not constitute much of a risk,” O’Brien says. It will burn and emit smoke, but it won’t create large sparks or flames, he notes.

The chemicals used to detonate air bags also raise concerns about whether processing them is harmful to workers or the environment, Thornton says. Until the early 2000s, automobile manufacturers used sodium azide, a highly toxic and flammable substance, as the propellant, Byrne says. According to ISRI’s policy statement, sodium azide exposes workers to a potentially harmful toxicant. Exposure to above-threshold limits could lead to nausea, headaches, blurred vision, deficient oxygenation of the blood, or rapid heart action. “If I were the safety and risk manager, the only level [of exposure] I’d be comfortable with would be zero,” Byrne says. Today, manufacturers use non-azide chemical propellants such as guanidine nitrate, which is less toxic and not as hazardous during the recycling process, he says. Prolonged exposure could result in skin burns and ulcerations, and overexposure by inhalation could cause respiratory irritation, however. Byrne suggests asking manufacturers for safety data sheets, which contain chemical hazard information. “You have to know what you’re dealing with. Make it part of your standard operating procedures to know what these materials are because there are different technologies even within the same vehicle.”

Although the gas the combustion process produces is not hazardous to people—“It’s nearly all nitrogen”—another concern, Byrne says, is the heat air-bag deployment produces. During combustion, internal temperatures in the inflator are very high, and while the gas cools rapidly, burns are still possible from the venting hot gases. “When it explodes, it could have a temperature of 2,000 degrees [F],” Nelson says.

Risk Management Approaches

Despite wide agreement about the source and nature of the risks air bags pose, there’s no agreement on the best way to reduce or eliminate the risks. At least five states—Delaware, Minnesota, New York, Oregon, and Vermont—require air-bag deployment prior to shredding vehicles, says Michael Wilson, CEO of the Automotive Recyclers Association (Manassas, Va.). But many states don’t tell recyclers how to accomplish it, Zaidel says. “There’s so much gray area.”

Just locating air bags for deployment or removal prior to shredding could be difficult, Byrne says. Not all of the locations have markings, such as “SRS” or “Air Bag,” and some of the labels you do find might not identify the exact location. “The number of places you can fit an air bag is surprising,” he says. Typical locations include the steering-wheel assembly, dashboard, seats, doors, and overhead roof rails. Recyclers say they’re taking one or more of the following approaches to the air bags in their ELVs.               

Deployment. Byrne strongly recommends manually deploying air bags, if possible, while they are still attached to the vehicle before it goes into the shredder. “The gases move at such a high rate of speed that you really have to secure [the air bag] to a fixture [to deploy it safely], and the car is the logical way to do it because it serves as an in situ restraint,” he says. “If it’s not secured, it’s a potential missile. These things can cut right through a human body.”

Although Sadoff Iron & Metal Co. (Fond du Lac, Wis.) says it doesn’t receive many vehicles with live air bags, it has developed an internal process for trained employees to deploy the air bags when one does arrive, says David Borsuk, manager of industrial marketing and quality control. Wisconsin requires air-bag removal or detonation prior to vehicle crushing or removal of auto parts, Borsuk says. He likens it to removing mercury switches: “It’s just one step” in making the vehicle safe for recycling. Thornton points out, however, that “the mercury switch problem will go away for the metal recycling industry; the air-bag problem will continue and is getting bigger because manufacturers keep adding more.”

Some recyclers say they have created their own deployment systems using alligator clips, a vehicle battery, and at least 30 feet of wire, but they decline to share the details. The Automotive Safety Council recommends using procedures from the Warrendale, Pa.-based Society of Automotive Engineers International, standard SAE J1855. The council’s Campbell explains that the standard outlines basic procedures for using remote deployment systems currently on the market—or splicing into locations vehicle manufacturers have identified to deploy electrically activated air bags in ELVs prior to recycling. (Find the standard online for $70 at standards.sae.org/j1855_201002.) Hajkus reports that a consortium of automobile and air-bag manufacturers, the U.S. Council for Automotive Research (Southfield, Mich.), developed a free, four-page pamphlet, dated September 2002, that outlines how to remove, handle, or deploy air bags. Recyclers can locate the PDF by conducting an Internet search using its title, “Safely Deploying Single-Stage and Two-Stage Air Bags in End-of-Life Vehicles.”

Prior to deployment, workers must disconnect the vehicle’s battery and allow the back-up capacitor of the air bag’s electronic-control unit to discharge, Byrne says. He recommends waiting an hour after disconnecting the battery before deployment and removal of the spent module from the vehicle. Without an electrical source, “it has no firing means,” he says. But he recalls incidents in which air bags deployed and injured rescue personnel because the control module still contained residual power in its capacitor even though the responders disconnected the vehicle’s battery. “So you must wait long enough for the capacitor on the electronic control module to discharge,” Byrne says.

Deployment, if it can be done safely, might seem like the easiest and best option, but Zaidel points out one complicating factor: Many states define deployment of air-bag assemblies as treatment of hazardous waste, which raises permitting and regulatory issues for recyclers. That means manually deploying the air bags might not be a best practice in such states, he says, cautioning recyclers to review local and state regulations. In contrast with those regulations, Wisconsin’s approach seems to satisfy both safety and environmental concerns. Its regulations specify that “deploying airbag canisters accidently or intentionally is not considered hazardous waste treatment subject to licensing if components of the airbag are recycled separately or with the vehicle. Once deployed, materials from the airbag module, such as scrap metal and plastic can be safely removed for reclamation.”

Removal. Some auto dismantlers and recyclers choose to remove air-bag modules for their resale value or recycling elsewhere. ARA supports the reuse of undetonated, structurally sound air bags when the components need replacing and a customer consents, Wilson says. “Properly installed modules are cost-effective, viable alternatives for people who might otherwise have to total their vehicles because of the high prices insurers estimate it will take to replace air bags.” The Automotive Safety Council doesn’t support reuse, however. “While there’s nothing illegal about it, we just feel the history and pedigree of the unit is unknown,” Campbell says.

ARA has developed a voluntary certification program for its members, available at www.airbagresources.com, which provides guidelines for removing an original equipment manufacturer’s nondeployed air bag from a salvaged vehicle for installation in another vehicle, Wilson says. The protocol helps recyclers standardize their air-bag-related operations, track inspection records, and verify employees are trained and certified to remove air bags. The Automotive Safety Council offers a March 2012 document in its online library, “Guidelines for Safe Handling of Airbags and Pyrotechnic Seatbelt Devices,” which covers general information about air bags, handling do’s and don’ts, storage, and shipping (find it at www.aorc.org/resources_passive.asp?VideoID=66#docs).

Workers who remove air-bag modules should keep their head away from potential air-bag locations, Byrne says. Manufacturers have designed the systems to move from impact detection to the first release of gas in about 3 to 4 milliseconds, with peak pressure occurring at about 40 to 50 milliseconds, he explains. The entire process happens in one-twentieth of a second. Frontal air bags, once fully inflated, reach about 30 pounds per square inch of pressure, he says, “about as hard as a tire on a car. It’s not like getting hit with a big, soft pillow.” Employees could receive serious or fatal injuries from the deploying air bag, Byrne says.

To remove an air bag, don’t cut the wires of the unit’s electronic control module, “no matter how tempting it might be,” Byrne says. “Always unlatch the connectors. If you cut the wires, you risk defeating the built-in safety system,” and the air bag could deploy due to electromagnetic interference such as static electricity or radio frequency. “The amount of current [required to deploy] is extremely small.” Modules with their inflator housing and shorting clip intact “have an extremely low probability of deploying,” Byrne says, “but if the clip is disconnected, then you have a whole different level of risk,” he warns.

If you must pick up a live module, carry it with both hands with the cover away from your body and place it face up on a spark-free surface, Byrne says. Store undetonated air bags in tightly closed containers in secure, cool, and well-ventilated areas away from water.

Never cut, rupture, weld, drill, or puncture any part of the module or inflator, Byrne says. And don’t try to randomly disassemble it. Manu­facturers friction-weld the inflator housings without fasteners, he says. They “were never meant to be disassembled.” One reassuring note is that dropping an air-bag module or inflator canister—or banging it with tools—is unlikely to set it off, Byrne adds.

For handling and transporting air bags that do not contain sodium azide, ARA recommends the following best management practices:

• Train and certify employees involved in extracting, inspecting, and handling air-bag units.
• Store undeployed air-bag units indoors, protected from the weather, until resale or disposal, if necessary.
• Train and certify shipping employees to DOT, state, or local rules regarding air-bag shipments and ensure compliance.

If the inflator contains sodium azide, ARA urges recyclers to follow state guidelines for handling the systems.

KPA Services provides advice about handling and shipping hazardous materials, including air bags. “If it’s out of the vehicle, our recommendation would be to recycle it through one of three recyclers who have air-bag recycling operations or services,” Zaidel says: PARC, MKC Enterprises (Doraville, Ga.), or Quest Resource Management Group (Frisco, Texas).

PARC uses an 8-foot by 3-foot by 3-foot oven to heat the canisters it receives to 1,000 degrees F, which deploys them. “It’s almost like a giant popcorn popper. It’s a constant pop, pop, pop,” Nelson says. The entire process takes about an hour and 15 minutes. The company receives 300 to 400 complete modules or 5,000 to 6,000 canisters a day, mainly from air-bag manufacturers, Nelson says, but it also accepts them from recyclers when it has available capacity, Hajkus says. Workers disassemble whole air-bag modules by hand, wearing high-quality leather gloves to reduce the threat of static electricity as well as safety lenses and thick coveralls, Nelson says. PARC contracts with other companies to recycle each of the components. “All of it is recyclable,” he says.

Shredding. Autoliv’s O’Brien urges recyclers to remove or deploy air bags before vehicles are shredded. But those recommendations concern Steve Levetan, executive vice president of Pull-A-Part (Atlanta), because the process could introduce risks to workers who have to handle them, he says. “We don’t want people touching them. And then what do you do with the bags?” he asks. Instead, the company leaves the air bags in the car hulks it crushes and sends to shredders, Levetan says. SA Recycling relies on shredding to deploy the air bags because with the volume of vehicles the company processes and number of air bags they contain, it doesn’t consider the other alternatives practical, Deiro says.

One way to make it more likely air bags will deploy or otherwise become totally disabled while in the shredder box is to shred material to a higher density by using smaller grates, suggests Scott Newell Jr., CEO of The Shredder Co. (Canutillo, Texas). “A higher density decreases the chance of a canister surviving the shredder process.” The process would use more electricity and put more wear on the hammers and grate bars, he points out, but because most shredders are underutilized, it is unlikely to affect overall productivity, he says. Newell shared the concept at an ReMA Shredder Committee meeting, where “everybody agreed it would make the situation better, but nobody was ready to say it would be 100-percent effective—including me,” he says.

Regardless of which approach you use, “we have to educate work forces about the dangers” of undeployed air bags, Thornton says. “Most people don’t know what a canister looks like after it passes through the shredder.” Further, canisters sometimes show up in other scrap, Smith warns, so it’s important to train employees to recognize them in their many possible guises. He recalls an incident in which a worker attempted to torch off a “tail” from a bundle to square it up. The unknown material turned out to be part of a pressurized air-bag canister, which exploded and hit the man in the groin. SA Recycling uses photographs or actual examples of air-bag components such as canisters, when available, to train workers about prohibited items, Deiro says. “If they encounter an item, they remove [it] and place it in a 55-gallon drum full of water.”

Seeking a Safety Consensus

Several sources for this story note that nothing in air bags’ design seems to take into account their end-of-life management. ISRI’s Design for Recycling Task Force “has looked at the issue for many years,” says Manny Bodner, president of Bodner Metal & Iron Corp. (Houston), chairman. Manufacturers need encouragement to implement “the principle of recycling at the initial stages of design,” he says. ISRI’s policy calls for manufacturers to develop safe and efficient procedures for the removal of air bags that “minimize the potential for confusion and mishandling during removal.”

Denbo agrees with that goal. As they are now, air bags put “an unreasonable risk on our employees’ safety. There’s got to be a way for manufacturers to create a central detonation point to deploy [them]. Otherwise, we’re dealt the hand of having to deal with the material as it presents itself.” BMW reportedly was evaluating creating such a kill switch, Thornton says. U.S. CAR discussed central deployment of air bags years ago, Autoliv’s Nelson says. “I’m totally amazed that they haven’t moved forward with this.”               

The absence of a clear direction concerns Denbo. “If it gets to be too much trouble, the price for automobiles will drop,” he says. Thornton agrees, cautioning recyclers that not addressing air bags can create problems with scrap consumers. “From a practical standpoint, [consumers] could reject an entire load based on one air bag.” Undeployed or partially deployed canisters can be “sealed units,” which can explode if they enter the melt at a mill or smelter while sealed or with water trapped inside. 

Thornton suggests that because some states mandate that recyclers remove or deploy air bags prior to shredding, shredder yards should refuse to take ELVs that contain undeployed bags—or offer less for them to cover the time it will take to remove or deploy them. Recyclers could create a staging area at their feeder yards or require suppliers such as auto dismantlers to do the work, he says.

As chairman of the ReMA Safety and Environmental Council, Paul Brenner, president of Brenner Recycling (Hazleton, Pa.), has formed a working group tasked with developing best practices for managing air bags in ELVs. “It’s going to be a very difficult task,” he says, but he hopes to get manufacturers and other stakeholders involved. To date, stakeholders have considered the issue in “bits and pieces,” Borsuk says. “We need a holistic approach.”

ISRI’s policy envisions the ideal solution from the recyclers’ perspective. It supports legislation or regulations that create a system to identify ELVs sold in the United States containing undetonated air bags, require the removal of air-bag canisters from auto hulks prior to delivery for recycling, or develop a market-based system to remove undetonated canisters prior to delivery of the hulks for recycling. If a market-based system is not viable, it recommends the federal government create incentives for the launch of individual statewide take-back programs for recovering air bags prior to recycling. For example, it states, “Failure of a state to establish such a program could result in the federal government’s withholding part of the state’s allocation from the Highway Trust Fund.”