The flow-past chamber: an improved nose-only exposure system for rodents.

We have designed a nose-only inhalation exposure chamber in which fresh aerosol is flowed past each exposure port and exhaled air is immediately exhausted. This allows all animals in the chamber to be exposed to the same aerosol concentration. In tests comparing initial lung burdens (ILB) of animals exposed in a standard chamber with those of animals exposed in the flow-past chamber, coefficients of variation in ILBs were significantly smaller for the latter.