A respiratory therapy device comprises a pneumatic control unit connectable to a source of medical grade oxygen for supplying oxygen to a first control unit outlet port at a first set of conditions and to a second control unit outlet port at a second set of conditions. First and second transfer conduits are in fluid communication with the first and second outlet ports. Each transfer conduit defines at least part of a flowpath to destination. Each flowpath includes a filter. A related filtration module comprises a filter housing defining two or more filter compartments. The housing has an input side with a gas inlet in fluid communication with each of the filter compartments and a gas outlet in fluid communication with each of the filter compartments. A filter element resides in each of the compartments intermediate the gas inlet to the compartment and the gas outlet from the compartment.