Generation of constant formaldehyde levels for inhalation studies.

Development of the described formaldehyde generator was undertaken to provide researchers engaged in inhalation studies with the capability to produce constant and controllable levels of formaldehyde in air. Depolymerization of purified paraformaldehyde under rigorously controlled conditions in a modified Freeland calibration manifold is employed. The desired formaldehyde concentration in the exposure chamber is achieved by adding an appropriate fraction of the generator effluent to the normal air supply to the chamber. Variation in generator formaldehyde concentration is less than +/- 11% over a three-day period and less than +/- 2% over short periods (36 seconds).