Twelve minutes later, Pasadena police said it's a "very serious leak." But three minutes after that, the city of Pasadena said, "there's no danger to the public."
And now, officials are asking questions about what happened at the plant.
"I knew right away that it was something bad," said resident Daniel Saucedo.
Saucedo was driving home from work when he saw the orange cloud not a mile from his home. It was around 4:15pm when plant management says the nitric acid plant unexpectedly shut down. That, along with a pipe leak, sent a cloud of nitric oxide into the air.
Motorists on 225 were engulfed and the fire department started getting calls.
"I don't think they had anticipated the release getting as large as it did," said Chief Lanny Armstrong with the Pasadena Fire Department. "When the traffic started driving through the cloud, we actually were getting calls from Transtar as well. They had their cameras trained on the cloud."
The city shut down the highway from Richey all the way to the Beltway. An hour after the original incident, a shelter-in-place was issued, which Saucedo and his family didn't think twice to follow.
"When I saw a big old heavy cloud, I didn't think anything of stepping outside," said Saucedo.
The bad news is that nitric oxide is a toxic irritant that you don't want to inhale. The good news is that it has very high vapor pressure, so it dissipates quickly. After some air monitoring, the all clear was sounded around 6:15pm.
The plant manager maintains they did everything right.
"I apologize to the community that we did cause some inconvenience, but we thought it was necessary to be safe and to take some precautions," said plant manager Jacques Joseph.
The Pasadena fire chief doesn't disagree, though he says the city would have liked to have been notified earlier.
"There is room for improvement and we will discuss that with the facility," said Armstrong.
The plant did follow protocol by notifying the community and neighboring emergency management. The question as authorities do their review is whether or not they did it fast enough. Three people who drove through the orange cloud went to the hospital, saying they were having trouble breathing.
Nitric acid is a colorless, highly corrosive liquid which can cause severe burns and irritation to the eyes. The CDC says prolonged exposure could also lead to bronchitis and other serious health problems. Nitric acid has various uses, including fertilizer, military explosives, photo engraving and gold and silver separation.
Tuesday night, Air Products and Chemical Plant released the following statement:
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At approximately 4:45 pm CT, the Air Products' nitric acid plant in Pasadena, TX shut down unexpectedly. This was followed by a pipe leak that resulted in the formation and release of a nitric oxide vapor cloud. The cloud passed to the southeast in the direction of Highway 225. There was no fire nor injuries at the plant or significant damage to the plant itself. Emergency responders were notified immediately according to protocol.
The leak was contained and the plant was secured. The cloud had dissipated into the atmosphere by approximately 6:15 pm and the plant all clear signal was sounded. Air monitoring was performed in the surrounding area by the Harris County HAZMAT. Nitric oxide levels were non-detectable and the shelter-in-place was lifted by authorities.
We are investigating this incident to determine the root cause. We regret any inconvenience and delays this may have caused.
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