More than three-dozen construction workers were treated for chlorine inhalation after a June 24 leak at Dow Chemical Canada Inc.'s vinyl chloride monomer plant in Fort Saskatchewan, Alberta.
The 1:25 a.m. leak lasted five minutes and forced the evacuation of both the monomer plant and Dow's nearby polyethylene plant. Thirty-eight workers were treated at the company's on-site health center, and nine of those people were taken to the Fort Saskatchewan Health Centre for further treatment. They all were released by that afternoon.
Plant general manager Bob Knee said about 200 workers were at each plant at the time of the spill. Each plant usually only employs 70, but expansion and installation of new technology has stopped PE and vinyl chloride monomer production and brought in a large number of contract employees.
The workers suffered from burning eyes and sore noses and throats, but none developed the cough that is a symptom of more severe chlorine inhalation, Knee said. The leak was a result of an overpressured vent in a new ethylene dichloride reactor the plant is installing, he said. The excess pressure caused the chlorine to escape through the vent.
Knee added that preliminary investigations have shown instrument failure and inaccurate calibration may have played a role in the leak. The incident is being investigated by Alberta Environmental Protection.
Expansion work was stopped for six hours because of the leak.