The disclosure relates to an apparatus (10) for decontaminating an enclosure that includes a passage having an inlet (18) to receive a carrier gas from the enclosure, an outlet (31) to discharge the carrier gas to the enclosure, a fan (21) for causing a low of carrier gas through the passage from the inlet to the outlet, and a vapour generator (19) where a decontaminant vapour is introduced into the flow of carrier gas to be discharged with the flow at the outlet to decontaminate the enclosed space. A further fan (33) delivers a separate flow of gas from the enclosure bypassing the passageway in which the decontaminant vapour is introduced to be delivered into the enclosure from outlet vents (32) adjacent the vapour outlets (31) to assist in dispersing the carrier gas containing decontaminant vapour throughout the enclosure.
