A breath guard includes a first support, a second support, a guide rail coupled to the first support and extending in a substantially longitudinal direction, the guide rail including a rack defining a series of teeth, an adjustable panel extending between the first support and the second support, and an adjustment mechanism including a pawl rotatably coupled to the adjustable panel and configured to selectively engage the teeth of the rack. The adjustable panel is rotatable relative to the guide rail about an axis of rotation that extends laterally. The adjustment mechanism is configured to prevent longitudinal movement of the adjustable panel relative to the guide rail in a first direction and allow longitudinal movement of the adjustable panel in a second direction when the pawl engages the teeth of the rack, such that the adjustable panel is selectively repositionable between a series of longitudinal positions.