The invention relates to fluid distribution in an exposure device. The exposure device, in some examples, is a device for exposing living cell cultures or cellular tissues to a fluid such as cigarette smoke, air and/or other gases or gas mixtures, for use in studies of the effects on the cell cultures or tissues of their exposure to the fluid. A fluid distribution member is described for distributing the fluid in the exposure device, the member including a plurality of apertures in a surface arranged such that, when the distribution member is fitted to the fluid exposure device, the distribution member receives fluid applied to the surface of the member and distributes the fluid, via the apertures, to samples to be exposed to the fluid in the exposure device.