Lung clearance of 4-micron particles coated with silver, carbon, or beryllium.

Lung clearance in rabbits during the first week after inhalation of 4-micron teflon particles tagged with chromium-51 and coated with silver, carbon, or beryllium was studied by external measurements of the radioactivity in the lungs. Ten rabbits were exposed to silver- and carbon-coated particles on two separate occasions within 3 weeks. Clearances of the two types of particles were quite similar. Clearance in eight other rabbits that had inhaled silver-coated particles was quite similar to clearance in eight rabbits that had inhaled beryllium-coated particles. The result is regarded as evidence that alveolar macrophages do not play an active role in removing intact particles from the lung the first week after inhalation.