Management cleared two propane-powered forklifts of any culpability in a carbon monoxide poisoning incident at the Columbia plant of American Corrugated Products Inc.

A contractor's crane operating near the building was the source, says general manager Jeff Valentine. "It was out back where we had some windows open. Some work was being done outside the building."

Local personnel from natural gas distributor Atmos Energy Corp measured high carbon monoxide levels exceeding 80% inside the American Corrugated plant on 9 November. A forklift operator with five years' seniority left work because of a headache. Later, the fire department transported him to a medical centre. Twelve staff were evacuated.

A hazardous materials crew evaluated the situation. Use of fans over two hours reduced the level below 10%.
"We have not had any more spikes," Valentine reports.

The Columbia plant operates two propane-powered forklifts, a Yale with lifting capacity of 4,500 lbs. (2,025-kg) and a Nissan with 3,000 lb. (1,350 kg) capacity.

Columbus, Ohio-based American Corrugated is a major independent packaging manufacturer with seven plants in Tennessee, Ohio, Indiana and Michigan.