Proper airflow direction is a critical factor in keeping the indoor air fresh and free of odors and/or fumes. Large commercial areas with plenty of activity like warehouses, shopping malls, hotels and offices can heat up very fast, which can cause foul smells to materialize. Back draught dampers/backdraft dampers ensure that foul smelling air within the commercial area do not persist and that air is circulated in an energy-saving manner. These dampers allow the air to be pushed out of the room but they are designed to prevent the same air flowing back in. Back draft dampers are also used to reduce risks associated with industries where workers have to operate around hazardous vapors or fumes.