Abstract: Gas flux rate from a surface is measured using an elongated tubular housing having a lower open end and an upper open end with a support positioned within the housing a predetermined distance from the lower open end. A gas sampling wand extends into the housing from the upper open end and is supported on the support. The wand has a lower open end at the support generally co-planar with the lower open end of the housing. An air baffle is coupled to the upper open end of the housing for reducing velocity and pressure fluctuations of atmospheric air entering the housing from the upper end. A detector is coupled to the wand for measuring the concentration of selected gases within the housing. A funnel-shaped hood circumscribes the lower open end of the wand and increases the sample collection area of the wand. An air pump is coupled to the wand for drawing air and gases into the wand from the area adjacent the lower open end of the housing.