Sodium azide, the chemical that inflates auto safety air bags, is nasty stuff. It is highly flammable, often explosive and extremely toxic. It is so sensitive, in fact, that large explosions have been set off by workers performing such innocuous tasks as placing a wrench on a bolt or using a metal scoop near the chemical.

People who work with sodium azide must not breathe it or allow it to contact their skin. At moderate- or high-exposure levels, the chemical creates respiratory distress, including pulmonary edema, a condition that fills the lungs with fluid, sometimes causing a victim to drown in his own liquids. Lower-level exposure produces heart-function irregularities, including enormous drops in blood pressure and occasionally cardiac arrest.

Long-term exposure to the chemical has been shown to cause mutations in plant and animal genes. For years it has been suspected of being a carcinogen to humans, but the few studies in that regard have been inconclusive.

Sodium azide can behave unpredictably in the presence of other substances. When it comes into contact with an acid, or even water that is slightly acidic, for example, it creates hydrozoic acid.

Hydrozoic acid gas is extremely toxic--one moderately strong whiff can cause convulsions and death. It has been extensively tested on laboratory animals, and its effects on humans are detailed in papers found in Nazi prison camps at the end of the Second World War.

Toward the end of the war, the Germans considered using it as a chemical-warfare agent.

TRW Vehicle Safety Systems in Mesa uses large amounts of sodium azide to make the safety air-bag systems installed in new automobiles. Something like five million pounds a year.

Safety and TRW, however, definitely are not synonymous.
While working with the chemical, TRW employees and subcontractors have started at least two dozen fires and explosions at the company's two East Valley plants.

TRW has improperly stored tons of sodium azide in Mesa for years. The company has failed to build safety systems it had promised to win approval for one of its Mesa plants.

And documents show that the company is putting large amounts of the chemical directly into the Mesa sewage treatment system, a practice which some experts say could have deadly results.

In the wake of a recent explosion that killed one worker and critically injured another, TRW has quite deservedly gotten bad press. Even the government has been critical.

But the City of Mesa and the State of Arizona have known about serious problems at TRW for a long time. And those governments have done virtually nothing to fix the problems.

In fact, over the past few years, the City of Mesa has been a very good friend to TRW Vehicle Safety Systems.

If you get in a front-end accident in a car equipped with air bags, here's what happens: Electronic sensors mounted around the front of the car measure its deceleration. If it is severe enough, an electric charge is sent back along the steering column and into the air-bag inflator assembly, nestled in the steering wheel beneath a carefully folded and packed bag.

The jolt of electricity sets off a booster charge, which triggers the detonation of a stack of propellant disks arranged around the core of the unit. Think of the booster charge as a blasting cap and the disks as dynamite.

The disks are extremely volatile and burn instantly, releasing a large amount of nitrogen gas as they are consumed. It is this gas which leaks out of the inflator assembly and fills the bag. If everything goes according to design, the bag instantly inflates, cushioning your upper body and keeping you from slamming into the steering wheel and windshield.

In order to be effective, the detonation and inflation of the bag must take just 40 thousandths of a second. Obviously, the propellant used to inflate air bags has to be extremely volatile; otherwise, it couldn't burn quickly enough to work.

The principal ingredient in air-bag inflators is sodium azide. Until recently, this chemical was used in small quantities as a laboratory preservative, in larger quantities as the inflating agent for airline emergency ramps and in even larger quantities by the explosive and munitions industries.

Now, though, the demand for air bags has skyrocketed, and manufacturers have been scrambling to boost production. Environmental and health researchers, charged with determining the chemical's possible hazards, have been kept just as busy.

Eric Betterton works out of a medium-size office on the fourth floor of the Physics and Atmospheric Sciences Building at the University of Arizona in Tucson. He is one of the few people in the country who have begun serious study of sodium azide and the environment. Because the chemical was not used widely until air bags became common automotive equipment, information has been hard to come by.  

Betterton received national attention last year when he and other researchers revealed that the chemical can be released in junkyards when cars equipped with air bags are crushed. The team found that sodium azide is water-soluble and, therefore, a threat to ground- and surface-water sources.

Betterton says the chemical, which degrades very slowly, is especially hazardous when it comes into contact with acidic water, such as acid rain. Only a low level of acidity is necessary to start changing sodium azide into lethal hydrozoic acid.

That transformation may be occurring right now in the Mesa sewer system. Mesa officials have allowed TRW to greatly increase sodium azide levels in wastewater emitted from the company's plants, even as the city has relaxed its controls on the acid content of that wastewater.

Betterton says TRW is putting enough sodium azide--and enough acidic water--into the Mesa sewer system that significant amounts of the chemical probably are turning to hydrozoic acid gas.

If air containing a concentration of the gas escaped from the sewers, he says, anyone who got a solid whiff of it could die.

The City of Mesa has been less than diligent in policing TRW's sodium azide emissions.

City inspectors have repeatedly cited the company for violating discharge limits for the chemical. But, as the file on TRW's wastewater violations has grown thicker and thicker, higher-level city officials have become ever more accommodating.

Now, TRW is allowed to flush away levels of sodium azide that are hundreds of times higher than they were just a few years ago. At the same time, the city has raised the level of acidity it allows in TRW's wastewater.

The regulatory changes seem to follow a pattern. Since 1989, the city has set levels, and TRW has exceeded them. City inspectors have issued violation notices to the company. Occasionally, a small fine has been assessed.

And then the city has raised the emission levels for sodium azide.
When TRW asked to have its discharge limits raised to the current level, the city gave a novel response.

Mesa told TRW, a proven violator of the city's own environmental regulations, to hire a consultant to study the issue for the city. The consultant, the firm CH 2M Hill, issued a report that downplayed the possibility of hydrozoic acid production. The report also determined that no other hazards would be created by the higher sodium azide levels the company was requesting.

The report, however, does not appear to address the situation that currently exists at TRW's Mesa plants. The report's "worst-case scenario" assumes that the wastewater coming from those plants is significantly less acidic than the water the city allows TRW to discharge. In fact, TRW is currently allowed to discharge water that is ten times more acidic than the consultant's "worst case."

Nonetheless, the city accepted the consultant's recommendations, and allowed TRW to raise its discharges yet again.

"Basically, we were very comfortable with what the study said," says Richard Bradford, a water quality engineer for the city. "It looked like no harm would be done to the system."

In the spring of 1990, TRW had a big problem: The government of Quebec, Canada, had just shut the plant where the majority of its air bags were built. What the company needed was a place to move, set up shop and get back in business. Fast.

In April 1989, TRW had purchased air-bag operations at a site on North Higley Road in Mesa from Talley Defense Systems, Inc.

The next year, the company wanted to begin construction on a newer, bigger site a few miles away, at Germann and Signal Butte roads. Mesa was eager to do whatever it could to attract the corporate giant. The city installed five miles of gas line, six miles of water line and nine miles of sewer line.

These items are listed in the 1990-91 Mesa City Budget as "TRW improvements." They cost the city $3.1 million.

Mesa annexed 640 acres the facility would occupy, zoning it for suburban use in February 1990. Less than a month later, TRW requested that the land be rezoned for industrial use. A company official told the board that only manufacturing work would be performed; any hazardous materials used in that process would be removed from the site.

In mid-March, the Mesa Planning and Zoning Board unanimously approved the rezoning, with several conditions. First, the board said, development on the property had to conform to a site plan TRW had shown at the meeting--a plan with no mention of hazardous waste. Also, the company had to landscape the 30-foot-tall earthen berms that were to surround the buildings where the sodium azide would be handled.  

Those berms were meant to contain any explosions that might occur.
If there had ever been any doubts about whether TRW's development was on the fast track, they were erased just four days later, when the Mesa City Council approved the project.

TRW was just as quick to ignore the original plan for its new facility.
Although that plan mentioned nothing about hazardous materials or waste, huge amounts of sodium azide and its by-products have been stored at TRW facilities, often for extended periods of time.

In September, the state Department of Environmental Quality fined TRW $35,000 for failing to remove more than 20 tons of sodium azide waste from the site. TRW claimed that it had been unable to find anyone who would take the waste.

The company is still making that claim, and it is still storing the waste at the plant.

The company has yet to build the 30-foot-tall protection berms that were depicted in its original site plan.

Roger Rambo, Mesa's assistant building inspection superintendent, says the facility built by TRW is substantially the same as the plant originally proposed to the city.

He says the explosion berms were not required because buildings at the Germann Road site are far enough apart to keep an explosion from spreading. And so far, he has been right. Even though TRW is storing 20 extra tons of sodium azide waste on-site, there have been no blasts large enough to create a multibuilding inferno.

But that doesn't mean TRW handles sodium azide carefully.

For employees in TRW's Mesa operations, the most dangerous part of air-bag manufacture is the assembly process, when sodium azide is ground into a fine powder and mixed with oxidized copper. This combination is then pressed into the disks that fit inside the air-bag inflator unit.

At TRW's Higley Road site, the pressing is performed in 17 different bays, each approximately 15 feet square. Three walls of any given bay are constructed of one-foot-thick reinforced concrete. The fourth side of the bay is a steel "blowout wall," designed to give way in an explosion and lessen damage to the rest of the building.

On September 16, about 7 a.m., the blowout wall in Pressing Bay Number 9 got a real-life test.

Bay Number 9 had been closed for about two weeks. Subcontractors were installing an upgraded fire suppression system and other new equipment.

That morning, Tony Fox, a 38-year-old employee of Interstate Mechanical Corporation, told his foreman that he could not fit a piece of ventilation duct into the hole where it was supposed to go. The foreman told Fox to do whatever he had to in order to make the duct fit.

Fox had just begun grinding on the hole when there was an explosion. A spark from the grinder apparently flew through the hole and into a "dust bin," a trough filled with about 50 pounds of sodium azide dust and chunks. The dust bins hold scrap bits and pieces of the explosive disks--swept up from the floor and dusted off equipment in the pressing room--for reuse or disposal.

Fox was transported by helicopter to Scottsdale Memorial Hospital, where he died. Another man in the pressing bay suffered second- and third-degree burns over the front half of his body. Five other people were injured, including a female TRW employee in a corridor about 25 feet from Bay Number 9. The explosion was so violent that it threw her five feet; she landed against a steel locker.

After the blast, investigators found the remains of a holocaust, and the evidence of wanton disregard of the most obvious of safety rules.

A "bag house," a small room containing the bin of sodium azide scraps, had been blown to bits. Unburned propellant lay everywhere; investigators found that the blast had thrown one door frame from the bag house more than 400 feet. An 80-pound panel from the bag house was thrown 158 feet.

The renovation of Pressing Bay Number 9 was carried out not by TRW employees, but by subcontractors who later said they hadn't worried about the possibility of a fire or an explosion. They said they hadn't worried because TRW was supposed to have completely cleaned the area before the project began.

The bay had been washed out by TRW personnel on September 2, two weeks before the blast. But when fire investigators requested the checklists that would show more recent cleanings of the area, TRW officials said they couldn't find them.

The subcontractors had another reason to feel safe working in Pressing Bay Number 9. Before beginning work, they had asked TRW inspectors to sign a "flame permit"--a document that tells outside workers it is safe to begin work that produces heat, sparks or an open flame. Two TRW employees had signed such a permit just a few minutes before the explosion.  

A TRW supervisor who signed the permit later told fire investigators that he hadn't even been inside the pressing bay that morning. He said that he had inspected it on other days during the renovation, signing flame permits each time.

A TRW security officer who also signed the flame permit said he had been inside Pressing Bay Number 9 that morning, found no apparent dangers and assumed that the area was free of explosive material. When asked about the bag house and its dust bin full of sodium azide, the security guard had a puzzling reply: He didn't know what a bag house was.

Although the September 16 blast was the most serious so far at TRW's Mesa facilities, it is not an aberration. State, county and city records show that since 1989, at least 22 fires and explosions have rocked the two sites, injuring more than 20 people and in one case forcing the evacuation of nearby homes.

Such accidents seem to be the rule rather than the exception, not just at TRW's Mesa plants but at its manufacturing facilities all over North America.

According to federal, state and local sources, TRW plants in Mesa, Romeo, Michigan, and McMastersville, Quebec, have had at least 30 fires or explosions since 1988, in which at least 30 people have been injured.

Fires and explosions were occurring so frequently at the Quebec plant, in fact, that in 1990 the Canadian government forced TRW and its Canadian partner to stop operations.

TRW's sodium azide headaches are not over. The company may face criminal charges in the explosion that killed Tony Fox. The lawsuit over his death and his co-worker's injuries is likely to be long and expensive. The Occupational Safety and Health Administration has yet to issue its own report on the blast. It's a safe bet that report will be short on good news for the company.

There may be one bright spot on TRW's horizon, however. Some of the company's waste-disposal problems may soon be alleviated. The installation of a thermal treatment unit at the Germann Road site finally will allow the company to deal with some of the sodium azide waste generated there.

Back when the company was asking for approval of its new air-bag plant, of course, no mention was made of plans to use it as a hazardous-waste-treatment facility.

State environmental regulators say oversight of the new unit is the responsibility of the City of Mesa.

Mesa officials say close regulation won't be necessary. They express confidence in the company's thermal treatment plan, and say it poses no hazard to workers or the surrounding community.

Sponsor Content


All-access pass to top stories, events and offers around town.

Sign Up >

No Thanks!

Remind Me Later >