^ ^ "In the two hose style the exchanged air does not originate from the interior in the room or dwelling, but enters throughout the second hose". Experts123.com. Retrieved ten June 2015. Healthcare facility functioning theatres, through which air is filtered to higher ranges to scale back an infection possibility https://docs.google.com/spreadsheets/d/12u7rJLrjSWIMoTyNzJz1omJPJnoZX4A_U0YLwoyEYUk