May 07, 2014 - 06:49 AM
2 - it works by chasing the rodent out of the tunnel so that it can be killed. This is achieved by using some sort of technique such as a shotgun or a shovel. No kidding.
In either case, it is imperative that the tunnels be open enough so that the gas has a way to seep through it. If the tunnel is closed off, then there is no place for the smoke to go but up and into the air.
Hope this helps.