A method is provided for supporting environmental control in a semiconductor wafer processing space, the method includes: flowing a first gas under pressure in a first direction through a first diffuser tube, thereby generating a first lateral flow of gas through a sidewall of the first diffuser tube; flowing a second gas under pressure in a second direction through a second diffuser tube, thereby generating a second lateral flow of gas through a sidewall of the second diffuser tube, the second direction being opposite the first direction; combining the first and second lateral flows of gas within a housing; and outputting the combined lateral flows of gas from the housing to produce a laminar gas flow covering an opening to the semiconductor wafer processing space.