A ductless fumehood system comprising: at least one ductless fumehood comprising a housing; a workspace formed within the housing; a door for selectively closing off the workspace; an air inlet for introducing air into the workspace; a master module for receiving air from the workspace, purging unwanted substances from that air, and then exhausting that filtered air to the ambient room atmosphere; and a slave module for receiving air from the workspace, purging unwanted substances from that air, and then exhausting that filtered air to the ambient room atmosphere; wherein the slave module is in communication with the master module such that the master module central processing unit is capable of (i) controlling the operation of the active elements of the slave module, (ii) detecting a function failure of the slave module, and (iii) activating the master module alarm in the event of a failure within that slave module.