An uncontrolled release has occurred at the Poolbeg Incinerator.
11 men have been treated in hospital following the incident that took place overnight.
The HSA says it's treating it as a dangerous occurrence - however its not yet known what substance was released.
First aid was administered at the scene and the men attended St Vincent's hospital - two are being kept under observation.
HSA and EPA Inspectors are due on site and an investigation's underway.
