September/October 1996
Air bags are great for protecting motorists from harm, but, when undeployed, pose environmental and safety concerns for auto recyclers. Though solutions are in the offing, it could be years before the problems are completely addressed.
By Lynn R. Novelli
Lynn R. Novelli is a writer based in Russell, Ohio
By 2000, an estimated 75 million vehicles equipped with air bags will be on the road in the United States. Many will contain at least two of these safety devices—one on the driver’s side and another on the passenger’s side—with some incorporating more, such as knee restraints and side-impact air bags. Mercedes-Benz has gone so far as to propose cars equipped with as many as 14 air bags.
While the growing use of air bags is a safety boon for motorists, this trend presents potential hazards to auto recycling operations if any of the air bags from those millions of vehicles remain once the cars hit the scrap stream. In fact, auto recyclers—particularly shredder operators—have two distinct safety concerns about undeployed air bags reaching their facilities: the possibility of employee exposure to sodium azide, the hazardous chemical now used to inflate air bags, and the potential for undeployed air bags in car hulks to explode in a shredder, ignite other materials, and cause a major fire and/or additional explosions.
If you ask recyclers, most will say that these issues probably could have been prevented if automakers had only talked with them in advance. “I wish the car companies had consulted with the recycling industry as they were developing air bags,” says Marienne Galamba-Brown, vice president of Galamet Inc. (Kansas City, Mo.), a shredder operator. “We could have helped them design for recycling.”
But that wasn’t the way it happened. Thus, today, carmakers and air bag manufacturers are scrambling for after-the-fact solutions to the problems that have arisen, working with shredder operators and auto dismantlers to develop possible answers.
While these joint efforts have come later than recyclers might have hoped, they are, indeed, bringing about progress. Nevertheless, a final solution is probably a decade or more away.
Seeking Alternatives to Sodium Azide Dangers
One direction the automobile and air bag manufacturers have been heading in is finding a safer chemical with which to inflate air bags than sodium azide, which poses significant long-term threats.
Known to be associated with carcinogenic and mutagenic health effects, sodium azide is considered a hazardous substance by several government agencies, including the Occupational Safety and Health Administration. Swallowing as little as seven drops of the substance can be fatal, and breathing or touching it can also be lethal at higher exposure levels. In tests, one part sodium azide per million parts air produces a rapid change in blood pressure in laboratory animals, followed by convulsions and death.
In general, air bag inflator modules contain about one ounce of sodium azide, which is harmless when inside a sealed air bag container and after the air bag has been deployed. Potential health and safety problems can arise, however, if people, such as employees working on a shredding line, are exposed to an air bag container that has been breached or not fully deployed.
“Workers handling partially deployed air bags or leaking inflator modules are at risk of exposure,” confirms Ron Taylor, manager of health, safety, and environmental issues related to air bag disposal and recycling with Morton Automotive’s Safety Products Division (Ogden, Utah), an air bag manufacturer.
Sodium azide residue in shredder residue, water, and dust may also be hazardous. According to the National Highway Traffic Safety Administration, “the disposal of automobiles equipped with air bags that use sodium azide to generate gas could result in the accumulation of sodium azide or its products of degradation. These chemicals could be hazardous to workers ... or the environment.”
As these potential health and environmental hazards have come to light, air bag manufacturers and automakers have been seeking chemical alternatives. “We’re rapidly developing new technology that takes us beyond sodium azide,” says Taylor. “We’re into the third and fourth generations of air bags, and sodium azide is being phased out and replaced by other safer substances.”
Though environmental and safety concerns are driving this research, carmakers also have an interest in developing a chemical that will deploy air bags in a different manner, says Larry Daniels, staff project engineer for General Motors Corp. (Winchester Hills, Mich.) and his company’s representative to the Vehicle Recycling Partnership, a cooperative research venture of GM, Ford Motor Co., and Chrysler Corp. “Sodium azide causes the air bag to inflate all at once,” he explains. “The newer concept uses hybrid systems of compressed gas to deploy the air bag in a more controlled manner so that the volume of gas released into the bag varies with the severity of impact.”
In fact, such a system could deploy air bags differently, depending on the vehicle and crash conditions. A snub-nosed minivan, for example, would be equipped with an air bag that deploys instantly, while a big car with a lot of front crush space would have one that deploys more slowly. “The sodium azide reaction is an all-or-none one, and it is simply not suitable for the newer applications,” says Don Reed, Washington representative for the Automotive Occupant Restraints Council (AORC) (Lexington, Ky.). “Its use is already declining, and everybody knows that sodium azide is on the way out.”
Identifying and Dismantling The Problem
Eliminating the use of sodium azide-inflated air bags in future vehicles is all well and good, but what are recyclers supposed to do in the meantime about the millions of cars already on the roads with sodium azide-containing air bags? The only answer, most interested parties agree, is to identify and deploy or remove them—a strategy vital to solving shredder operators’ explosion concerns as well.
From a shredder operator’s perspective, the best time to identify undeployed air bags is when vehicles are being dismantled—and the American Automobile Manufacturers Association (AAMA) (Washington, D.C.) agrees. In the past few years, in fact, the association has mounted an extensive education program to instruct auto dismantlers in how and why to deploy air bags before sending hulks off for flattening and shredding. (For a description of AAMA’s recommended deployment procedures, see “Deploying Air Bags” on page 92.)
But until all air bags are removed from or deployed in hulks by dismantlers prior to shipment for recycling, shredder operators will continue to face potential problems. For them, the main problem is that it’s virtually impossible to determine whether a car hulk contains an undeployed air bag from visual inspection alone—the most common procedure for checking incoming loads.
To address this issue, carmakers have been exploring a variety of options including incorporating an identification system into their vehicles that would make it easier for recyclers to spot those with undeployed air bags.
But the approach that has received the most favorable reviews is electronic tagging, whereby air bags would contain an electronic device that would emit a signal in undeployed bags and automatically be deactivated in deployed bags. To make this system work, shredder operators would have to install a device to detect air bag signals in the same way they have installed radiation detection monitors—an idea that doesn’t sit well with some recyclers. “Why should shredder operators have to incur additional expense for electronic sensors or some other detection system?” asks Galamba-Brown. “It’s not our problem and disposing of air bags shouldn’t be our expense. Cars should come in here ready to be processed. Air bags should be handled by the dismantler, in the same way as CFCs, gas tanks, and PCBs.”
Automakers, meanwhile, have their own reservations about such identification devices, and not surprisingly, they’re related to cost. Though the devices “would definitely work,” Reed says, “the cost would be far higher than we hoped, about $4 or $5 a tag.” Thus, although AORC spent more than $150,000 to study the feasibility of electronic tagging, it has now abandoned the project, in part because of cost, but also because it views advances in air bag technology—such as replacing sodium azide—as a better solution to the problem. (This latter point disregards the explosion issue, which automakers and air bag manufacturers maintain should not be a major concern for shredder operators. For more on this difference of opinion, see “The Explosion Controversy” on page 96.)
AORC is reportedly looking into alternatives to electronic tagging, but so far has not come through with any recommendations.
In the absence of signal-based identification, there are still a variety of indicators in car hulks to identify those with air bags, says Susan Porter, a spokesperson for the Automotive Recyclers Association (Fairfax, Va.), the trade group that represents auto dismantlers. “Steering wheels containing air bags have a distinctive shape, and manufacturers usually emboss the words ‘Air Bag,’ ‘Supplemental Inflatable Restraint,’ ‘Supplemental Restraint System,’ or the letters ‘SIR’ or ‘SRS’ on the steering wheel hub for driver-side air bags, and on the right side of the instrument panel for passenger-side air bags,” she notes.
Carmakers also code air bag information into the vehicle identification number (VIN). In GM cars produced between 1988 and 1994, for example, the seventh digit in the VIN is the air bag code: a 3 or 5 in this position indicates a driver-side air bag and a 2, driver- and passenger-side air bags.
While these indicators are helpful, using them requires significant effort on the part of recyclers, Porter notes. At Galamet, two full-time inspectors make it their job to check out the steering wheels and the VINs of incoming hulks to determine if any contain an undeployed air bag, but this process is “very difficult,” not to mention time-consuming and hardly fail-safe, says Galamba-Brown. “They check as well as they can, but some cars come in so packed full of other scrap that it’s hard to see anything,” she explains. “They do the best they can, but they could miss some.”
Reaching Safety
Improvements in air bag systems and identification methods are obviously necessary and could be good news for recyclers in 15 years or so when cars with new generation air bags and identification systems are ready for recycling.
But what about all the vehicles recycled every year until then?
It’s quite possible that the recycling industry’s environmental and safety concerns regarding undeployed air bags will get worse before they get better. After all, driver-side passive restraint systems (either air bags or automatic seat belts) have been mandated by federal law since 1989, making those vehicles only a few years away from a major influx into the recycling stream. And after next year, all new vehicles sold in the United States must be equipped with both driver-side and passenger-side air bags. Adding significance to this situation are estimates that “at least 50 percent of all cars with air bags still have them in place when the vehicle goes to the shredder,” reports the air bag industry’s Taylor.
The needed solution for today, therefore, is “an industry-mandated standard that puts air bags in the same class as batteries or gasoline,” Taylor suggests. “Air bags should have to come out or be deployed before the hulk reaches the shredder,” he says.
This approach reflects ISRI’s position and has earned support from shredder operators. “Without some legislation about removing air bags, there’s the possibility that they will get into the shredder, and our workers could be breathing sodium azide for the next 10 or 15 years,” Galamba-Brown asserts, concluding soberly, “No, we do not feel safe.”
Deploying Air Bags
Air bag systems are generally designed to deploy in a frontal crash with an impact equivalent to running into a concrete wall at 12 mph or a parked car at 24 mph. At such an impact, sensors in the vehicle send an electric signal to the air bag’s inflator module, which is located inside a sealed aluminum or steel canister that contains a device similar to an electric light bulb filament. As the electric charge from the sensor runs across the filament, the heat generated initiates a chemical reaction that converts sodium azide to harmless nitrogen gas, which expands the air bag.
When air bags have not been so detonated by an impact, AAMA endorses deploying them according to the following 10-step system to “prevent vehicle shredder damage or contamination.”
- Disconnect cables from the vehicle’s battery.
- Wait at least 20 minutes for the energy reserve capacitor to discharge.
- Make a jumper wiring harness of two wires 30 feet or longer for remotely deploying the air bag. Alligator clips may be used. In accordance with items 7 and 8 below, an additional harness for dual air bag systems may be used.
- Locate and disconnect the wires leading to the driver and passenger air bags.
- Make sure the driver-side air bag module is properly secured to the steering wheel and the passenger-side air bag is also properly secured, if one is installed.
- Clear all loose items from front seat and instrument panel areas.
- Connect the end of the jumper wiring harness to the ends of the wires leading to the air bag module(s). If the vehicle is equipped with driver and passenger air bags, deploy one module at a time.
- With everyone standing at least 20 feet from the rear of the vehicle, deploy the air bag by touching the ends of the jumper wiring harness to the terminals of a 12-volt automobile battery.
- Leave the deployed air bag in the vehicle.
- Allow dust to settle before approaching the vehicle. If the powder or air bag dust contacts the skin, wash with water.
While most auto dismantlers report that they follow these procedures to deploy air bags, there are financial incentives to removing undeployed air bags intact, notes Automotive Recyclers Association’s Susan Porter. “Right now there’s such a high demand for air bags from collision repair facilities and insurance companies that they’ve started removing them for resale,” she says. Replacing a deployed air bag with a new one can cost up to $5,000, she notes, whereas installing an air bag from a scrapped vehicle can cut that cost 30 to 70 percent.
Despite such financial benefits, AORC and AAMA maintain that deploying air bags as directed is the only safe solution. “Using an air bag from a scrap vehicle to repair another car creates considerable risk that the air bag will not fit correctly or not be properly installed,” says Don Reed of AORC, adding that such a practice “opens up a number of safety and liability issues that no one wants to get into.”
The Explosion Controversy
The potential for undeployed air bags to explode in auto shredders is a threat many shredder operators fear. “Whether air bags will blow up in the shredder is one of the main issues at stake here,” says Jay Zimmern, general manager of Prolerized Schiabo-Neu Co. (Jersey City, N.J.). “The reaction in that inflator could be the extra spark needed to ignite other materials. What if there was gasoline in the shredder? You could have a major problem.”
Air bag manufacturers, automakers, and their trade groups, however, tend to downplay concerns about explosions and fires caused by air bags in shredders. “One air bag alone blowing up in a shredder wouldn’t cause a problem,” says AORC’s Don Reed, though conceding that “if there were enough hulks in there, you have the potential for shrapnel from the deployment.” Then again, he adds, “shredders are usually far out by themselves in the yard where shrapnel wouldn’t be a problem. If it were, some type of shroud on the shredder or protective gear for any personnel in the area would take care of any risk.”
Further discounting the explosion and fire concerns related to air bags in shredders, ARA and AORC representatives say their organizations haven’t received any reports of documented shredder explosions related to air bags.
But that doesn’t mean such incidents will never happen, cautions Zimmern. “We haven’t had any problems yet, but most of the vehicles we shred are 10 to 12 years old. In those that are newer, the air bags are deployed from a crash,” he says. “We haven’t had problems because we haven’t encountered undeployed air bags. It may be only a matter of time.” —L.R.N.•
Air bags are great for protecting motorists from harm, but, when undeployed, pose environmental and safety concerns for auto recyclers. Though solutions are in the offing, it could be years before the problems are completely addressed.