Airborne-Particle Deposition in the Respiratory Tract of Chickens

Thirty anesthetized, male White Leghorn chickens, approximately six months old (average body weight, 2.030 ± 0.048 kg.), individually inhaled radioactively labeled (I-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 μ.) 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.