A smoke stack is a tall exhaust
chimney or pipe usually found on refinery
sites or chemical processing plants
and used for the purposes of industrial emmissions
The world's tallest smoke stack can be found in Sudbury, Ontario, Canada (where it is also known as the Super Stack) servicing INCO's nickel refinery in nearby Copper Cliff. The stack was, at one point, one of the world's largest point sources of sulfer-dioxide. Today, water vapor is the Super Stack's primary output as scrubbers have significantly cleaned up its emmissions.