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Ammonia cloud may have been a danger, expert says

The giant explosion at a fertilizer plant in West, Texas, that killed between 5 and 15 people likely released a cloud of caustic ammonia gas that could have drifted for miles, experts say.

Ammonia’s sharp odor gives a good warning of its burning properties, but thick clouds can quickly overcome victims before they can even get away. The gas can burn the lungs and eyes, causing blindness and permanent respiratory problems.

“It is a respiratory irritant of the highest order,” says Dr. Arch Carson, a toxicologist and pulmonary specialist at The University of Texas Health Science Center at Houston.

“It causes severe respiratory system damage, eye damage and incapacitates people so they are no longer able to escape from exposure and help themselves,” Carson said in a telephone interview.

“It makes it impossible to escape a cloud. They don’t know which way to go,” added Carson, a former corporate medical director for Chevron Phillips Chemical Company.

Ammonia gas is colorless and it may not ever be known how much was released in the explosion at the plant. But Carson believes a concussive blast like the one in West would have released a significant amount. “The explosion itself was fairly horrific,” he says.

Hospitals that are treating victims of the West blast say they are seeing mostly cuts, broken bones, respiratory problems and just a few burns.

John Goodpaster, director of the Forensic Sciences Program at Indiana University-Purdue University Indianapolis, says plenty of ammonia would have been released.

“If you have a fire that generates enough heat and put it (near) a tank that has ammonia gas or an ammonia gas/air mixture in it…it will spontaneously ignite and the whole container will explode,” Goodpaster said in a telephone interview.

“You are going to have a lot of ammonia left over. It is not going to be all consumed in the explosion,” said Goodpaster, an expert in bombs made from fertilizer.

Carson, who has treated people exposed to the type of anhydrous ammonia stored at the plant, says it corrodes tissue. “It’s terrible stuff and it’s all around, distributed throughout our country and our cities,” he says. Treatment would be the same as for any burn.

The chemical is used as an industrial refrigerant. “There are accidents – a forklift may back into a refrigerator piping system or someone may be exposed while servicing a refrigerator compressor,” Carson said. He’s treated patients who develop permanent respiratory damage after breathing in the gas.

Anhydrous ammonia is a thirsty gas that grabs water – and in the process can burn skin, the inside of the mouth, throat and lungs. People who breathe in the gas will know it right away – not only does it stink, but the irritation can cause choking, burning and gasping. A bad burn will bleed, causing a pink, frothy foam at the mouth. In extreme cases, victims can suffocate.

It can irritate the eyes and even blind people. Safety regulations require plants processing or using ammonia to have water stations so people can wash it away quickly if they are exposed.

There’s not much treatment beyond washing the affected area with plenty of water and then treating any burns. Carson says emergency room staff will treat victims of ammonia burns in the same way they’ll treat patients coming in with burns from the fire or smoke inhalation.

Carson says in the case of a release, people should stay inside, close doors and turn off air conditioners. “We are lucky this is a rural area,” he says. Any ammonia cloud will dissipate eventually. “Over the course of usually the first several miles, it can still be extremely hazardous,” he says.

Children are especially at risk, according to the Centers for Disease Control and Prevention. “Children exposed to the same levels of ammonia vapor as adults may receive larger dose because they have greater lung surface area to body weight ratios,” the CDC advises.

“In addition, they may be exposed to higher levels than adults in the same location because of their short stature and the higher levels of ammonia vapor found nearer to the ground.”

Even ammonia used for cleaning can be dangerous. “Contact with concentrated ammonia solutions, such as some industrial cleaners (25 percent), may cause serious corrosive injury, including skin burns, permanent eye damage, or blindness,” the CDC advises.

“The full extent of damage to the eyes may not be clear until up to one week after the injury is sustained.”

Household cleaners that contain ammonia carry a clear warning not to mix it with chlorine bleach or any other product containing chlorine. That’s because the chemicals will combine to form chloramine, a highly deadly gas. 

But ammonia isn’t poisonous and it’s not been shown to cause long-term effects such as cancer. It won’t build up in the environment.


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