Thirty anesthetized, male White Leghorn chickens, approximately six months old (average body weight, 2.030 ± 0.048 kg.), individually inhaled radioactively labeled (1-128) monodispersed latex particles. Six birds each were exposed to one of five particle sizes (0.091, 0.176, 0.312, 1.1, and 3.7 to 7 microns). During exposure, the respiratory rate and tidal volume were monitored by a whole-body plethysmograph. Inhaled aerosol was detected externally for each of seven, equal-length sections along the axis of the body. Percentages of deposition for each section were calculated from the corrected time-decay activity.Significant differences (P < 0.05) were found for regional deposition as a function of particle size. The largest particles (3.7 to 7 |x.) were captured in the head and anterior trachea; other particles were deposited uniformly throughout the remainder of the system. The 1.1-micron-size particles were deposited primarily in the lung and posterior air sacs; those of 0.312-microns (having weak interception, impaction, and diffusion-capture mechanisms) tended to pass through the posterior to the anterior sacs (assuming the Hazelhoff-Bethe gas pathway theory); and smallest particles, influenced by diffusion, were captured in the birds' caudal regions.

The respiratory activity of poultry is highly susceptible to changes in respiratory dead space volume, airstream pressure, ambient temperature, and body position. A technique has been developed which will minimize these variables; yet permit the exposure and detection of inhaled aerosols. Monodispersed latex spheres of a known size are radioactively labeled following polymerization of iodine-127 onto the surface of the spheres. The bird is anesthetized and placed in a whole-body plethysmography. The liquid dispersed latex spheres are aerosolized from a nebulizer attached to a 10 p.s.i.g. compressed air line. The particles are electrostatically neutralized and routed to a plenum at near ambient pressure. The bird breathes at will through a unidirectional mask attached to the plenum. Following exposure the bird is euthanatized, the plethysmograph calibrated and the deposition in the respiratory tract measured at each of seven sections by a collimated, scintillation detector.