It appears natural causes are to blame for a strange smell that's been wafting over Newcastle in recent days.
Some say the big stink smells like sewerage, others believe the odour has a sulphuric smell.
Fire and Rescue NSW says it's received multiple calls from people concerned about a strong smell of gas, however no leaks have been detected.
The Environmental Protection Authority has investigated, finding it's likely to be a naturally occurring gas associated with stagnant water from the recent heavy rain.
It's believed the heavy fog in Newcastle in recent mornings is causing the smell to linger.