Methane is a naturally occurring gas that can sometimes be trapped underground.
If tunnelling releases it into a confined space and it comes into contact with a spark or another ignition source, it can ignite or explode, a government official said.
Methane is a naturally occurring gas that can sometimes be trapped underground. If tunnelling releases it into a confined space and it comes into contact with a spark or another ignition source, it can ignite or explode, a government official said.
