Abstract: A mobile unit for use in a remote enclosed space is disclosed. The unit not only heats or cools the air but also filters out toxic gases, it also is easily handled and extremely mobile. The unit is in the form of an open trailer comprising an air entry having a purifying means to remove toxic gases, cooling means, dehumidifying means and heating means. A ducting system from the air entry connects the purifying means, cooling means, dehumidifying means and heating means to an air exit. Fan means in the unit circulate air in the ducting system from the air entry to the air outlet, and the removable flexible conduits connect the air entry and the air exit to the enclosed space.