Dust overloading causes impairment of pulmonary clearance: evidence from rats and humans

There is increasing evidence, principally from experiments involving diesel exhaust particles, that pulmonary clearance becomes impaired after exposure to high dust concentrations. This effect is discussed here as a function of the exposure methodology as well as dust concentration. Metal oxide particles do not demonstrate this effect until higher exposures, presumably due to some solubility. Limited data suggesting impaired clearance at high dust loadings in humans is discussed. Thus, impairment may affect all materials and species if deposited in the lung at sufficient rates.