What's being described as an "absolute freak incident" at Westshore Terminals coal port Thursday afternoon caused a cloud of coal dust to briefly hover over the area.

Westshore general manager Denis Horgan said Friday that a sudden and unexpected gust of wind sent coal dust flying.

Horgan said the company takes wind very seriously and monitors it throughout the day and there was no indication of any high winds coming on Thursday afternoon.

He said wind speeds were at around 10 miles per hour (16 kilometres per hour) or below throughout the day when, at around 4:20 p.m., a sudden gust of 45 mph (72 km/h) hit the area.

Horgan said the company bases its daily dust control measures on the forecasted wind speeds and with no indication of high winds Thursday Westshore was not prepared for the 45 mph gust.

"It took us totally by surprise."

Horgan apologized for any inconvenience the dust may have caused local residents.