A leaking drum of a highly volatile chemical sparked an evacuation of businesses and residences near the New Plymouth railyard yesterday.
Emergency services were called to the Kiwirail freight centre in Smart Rd about 1.50pm.
New Plymouth fire deputy area manager John Nicholls confirmed the chemical had been identified as dimethylamine and was manufactured by Dow Agrosciences.
Dimethylamine is a colourless solvent with a number of industrial applications and a potent odour.
Dow Agrosciences could not be contacted for comment.
Mr Nicholls said the liquid chemical was in drums stacked on pallets in a container on a truck.
"In the container there were 80 200-litre drums and one of the drums was leaking," he said.
Firefighters from seven brigades wore protective clothing and breathing apparatus while they used a water spray to dilute the chemical and protect them from flammable gases.
The Taranaki Regional Council permitted them to let the watered-down chemical flow into the drains, he said.
"It's been diluted so it could be no longer harmful, but we have to seek their approval before we wash it away because it was going into the drains."
Mr Nicholls said there were no health concerns for anyone in the area, and Colson Rd had been evacuated because the wind was blowing in that direction.
"A 500-metre evacuation area was recommended on our data sheets," he said.
He had been told the chemical is used to make acids more soluble.
National Poisons Centre medical toxicologist Dr Michael Beasley said dimethylamine was a volatile chemical which could cause shortness of breath, respiratory distress, in severe cases pneumonitis or inflammation of the lungs, and irritate skin and eyes.
"It really depends on the level and length of exposure."
He said in large doses it could be lethal.
Colson Rd was closed while the spill was contained, and residents and businesspeople waited in the hot sun in Smart Rd for about 45 minutes before being told it would be at least another hour until they could return to their premises.
Most left shortly after.
Keith Maketoni, a rubbish truck driver, was unable to deliver his load to the Colson Rd landfill and waste transfer station.
"They told me it was a chemical spill and to turn around. I get paid by the hour so it doesn't bother me."
Deb Black, of Taranaki Paving, said she and children Elisha, 9, and Harrison, 8, had been evacuated by police.
"The police came in and said we had to get out."
She said she could smell something "quite acidic" in the air.
Jackie Poles Smith of the SPCA said she too detected a chemical smell which left a "metallic" taste in her mouth.
The SPCA was evacuated, with staff taking the five dogs in residence with them. SPCA manager Andrea Collins said they had tried to move some of the shelter's 60 cats and kittens from their outside runs to inside.
"It would have taken a huge amount of time to get them in cages and get them out."
After the spill was contained about 4.30pm, and residents allowed to return to Colson Rd, Ms Poles Smith contacted the Taranaki Daily News and said the cats appeared unharmed but would need monitoring for 48 hours.
She also said the SPCA would be closed today.
- Taranaki Daily News
Who do you think won Key v Cunliffe's second debate?Related story: Leaders debate reveals more even contest