The invention concerns a device for protecting premises in particular a tunnel against fire, consisting of a circular housing open at its two ends and deisgned to be fixed in the upper part of the premises to be protected such that its median axis (XX′) is substantially vertical, said housing comprising a substantially cylindrical lower part and an upper part substantially tapered in the shape of a bell, and containing part of vacuum-producing means capable of accelerating air circulation in and around the housing and spray means capable of injecting fine water droplets in the resulting circulating air.