A pump dispenser in which the associated container interior reduces its volume progressively as product is dispensed to avoid air contact with the product. An air trap member having a downwardly-convex dish form is provided below a floor of the associated dispenser module around an inlet to guide any such air away from the inlet. A peripheral portion forms a retaining lip for flexible wiping contact with the container wall interior, allowing air passage on assembly of the dispenser. A central tubular formation of the trap member separates the trapped air from the inlet and can be used to plug the trap member into the inlet.