Comparative lung deposition of charged and zero charged ultrafine particles in excised lungs. Final report, May 15, 1993--May 14, 1997

摘要

Airborne particles are charged by free ions in the air that are produced by cosmic rays and natural radioactivity. These airborne particles can carry one or a few charges depending upon their size. The particle charge distribution at equilibrium conditions can be estimated from the Boltzmann distribution. When these airborne particles are inhaled, some are deposited in the respiratory system. The deposition of particles in the respiratory system takes place via different mechanisms. Diffusion is the dominant deposition mechanism for the submicrometer ultrafine airborne particles. In addition, deposition may also occur as a result of electrical image forces. Therefore the electric charge imparted to the airborne particles by the free ions in the air can affect their deposition in the human respiratory system and be an important factor in determining the dose from inhaled toxicants. We hypothesize that ultrafine particles with diameters within the size range to which short live radon daughters are attached will exhibit an increased respiratory deposition resulting from a single charge.