Massive plumes of smoke that smothered parts of the city after a chemical fire broke out at Port Metro Vancouver contained a respiratory irritant dangerous to breathe in large quantities, according to health officials.

Vancouver Coastal Health said a container that went up in flames Wednesday contained an industrial disinfectant and bleaching agent called trichloroisocyanuric acid, exposure to which can be similar to breathing in bleach. The compound is often used in water treatment and swimming pools.

Some people in the area reported symptoms of burning throat and eyes, but health officials said the chemical's effects are short-term and should dissipate when the smoke clears.

Matthew Bowcott, who works near the dock, said he was on his lunch break when he drove into the smoke, which he described as smelling "sulphuric."

"I drove around the corner and heard all these ambulance, fire trucks," Bowcott said. “I drove right through the cloud of it and it smelled horrible, it was one of the worst smells I’ve ever smelled."

The smoke prompted a warning from Vancouver police to residents east of Main Street, west of Nanaimo Street and North of 1st Avenue to stay inside and close their windows. The shelter-in-place order was lifted several hours after the fire broke out, at around 5:45 p.m, but the city encouraged residents to stay away from the affected area.

Several libraries and temporary shelters opened their doors to those seeking refuge from the smoke.

Vancouver Coastal Health said anyone having difficulty breathing, especially those with lung problems, should seek medical attention immediately, adding that symptoms can occur within 24 hours of breathing the chemical.

Chemical fire 'consuming itself'

The blaze broke out at around 1:40 p.m. Wednesday in a shipping container buried six-deep and two-high in the Centerm terminal, according to fire officials. The terminal was quickly shut down and evacuated.

The fire was eventually upgraded to a four-alarm, and officials reported up to three containers were aflame at the height of the emergency. Fortunately, no serious injuries have been reported. 

Fire Chief Dan Wood said an investigation was underway to find out what caused the chemicals to burst into flames.

“In this situation, it was either contaminated or disrupted and it’s basically heated up and caught fire,” Wood said. “While it burns it will produce oxygen, serving itself, and it’s consuming itself.”

Wood said the chemical is a common product in the ports, and a substantial amount of it was in the container that caught fire.

Two Vancouver Fire and Rescue Services boats were dispatched to the north end of Centennial Pier to set up a staging area, and two aerials were sent up to dump water from above.

Port Metro Vancouver evacuated the 700-block of Centennial Road as well as the Clark Drive overpass and shut down all operations on the South shore. CP Rail also shut down a rail line while crews dealt with the blaze.

At least one West Coast Express departure was cancelled after authorities closed the rail tracks around the port, and TransLink told riders to find alternative transit to get home. Further delays and cancellations were expected.

Follow @CTVVancouver for the latest updates on this developing story