Phoenix Deputy Fire Chief Bob Khan says such a practice is not uncommon when fire personnel respond to hazardous sites. Often, like TRW, a company will have its own on-site response team to deal first with an emergency. Khan says when the fire department shows up, its primary jobs are containment and evacuation. That may necessitate waiting for an update on the situation from company employees and a delay before firefighters can go in and look for anyone who may be hurt, he says.
Nonetheless, Mesa's reports show that the city suspected that TRW officials needlessly prevented firefighters access in other emergency situations. Records reveal occasions in which fire personnel called to the scene believed the very existence of a fire, explosion or injured person was being concealed by plant officials.
One April 1995 report tells of fire personnel being held up at the guard shack while a security guard would not confirm that an explosion had even occurred. And in a report after a November 1995 blast, a fire investigator noted that officials were falsely told there were no injuries when seven people were hurt. He also accused TRW of trying to hide video footage of the explosion.
Mary Cameli, Mesa's deputy fire chief, says now that the 15-point safety plan and efforts by TRW to improve safety at the plant have been working. In 1997, she says, emergency personnel responded to 16 calls there -- down sharply from dozens in previous years. In 1998, there were three calls, an equal number in 1999 and none in 2000, she says.
Directly across from TRW's back fence is a sign announcing the future construction of a Mesa fire station. Cameli says the decision was made to locate a new station adjacent to TRW not because of any special concerns with the plant, but more in response to the huge population growth out there.
In newspaper opinion pieces, TRW says it has been trying to move away from the use of sodium azide in its air-bag production and has been phasing out the chemical's use in favor of newer, more benign propellants.
But the company continues to cite studies that it says show no toxic chemicals are present in smoke or emissions released from its facility. Those reports, TRW says, show the chemical quickly turns into harmless substances.
But the authors of the reports also clearly state that further analysis and data are needed to answer all questions.
Other scientists disagree with TRW's conclusions. They remain concerned about problems sodium azide may cause.
Andy Kleinhofs, a Washington State University researcher who has studied sodium azide and its effect on living things, was asked by Bunny Bertleson to read over some of those reports. In a written reply, he told her some of the conclusions were "illogical," that the amounts believed to be carried in plumes after an explosion were "purely a guess" and that the fixation on analyzing only explosions and burns concerned him.
"What about the daily discharge of sodium azide dust particles and hydrazoic acid (a gas). There is a good probability of chronic emission of these compounds into the air and dispersal to the area surrounding the plant," he wrote.
Studies and reports on sodium azide show just a few grams of the chemical can cause death. It can be inhaled, ingested or absorbed through the skin. And once inside the body, it can be absorbed into other organs. It is also described as a heritable mutagen, capable of altering genetic cells, an irritant to the skin, eyes, mucous membranes and respiratory tracts. The Environmental Protection Agency says it can harm the central nervous system, kidneys and cardiovascular system.
And, research shows, it results in cumulative toxicity; that is, repeated doses can cause greater damage than the individual amounts would suggest.
Eric Betterton, a University of Arizona professor whose research centers on the environmental effects of sodium azide, says while there have been studies about the impacts of sodium azide in individual cases of ingestion or exposure, there are no data about the long-term effects of ingesting smaller, nonfatal amounts.
He says even people living far from air-bag plants should be concerned about this for a couple of reasons. Uninflated air bags containing sodium azide are now accumulating in junk yards. Millions of pounds of discarded sodium azide could pose health hazards to entire communities, he says.
And transportation of the chemical is also dangerous. A small town in Utah was evacuated in 1996 after a truck spilled sodium azide on the highway. "If an 18-wheeler carrying a shipment of sodium azide rolled over on the Superstition Freeway, what would emergency personnel do?" he asks.