Particle size distributions in lungs and bronchopulmonary lymph nodes due to long-term exposure to coal fly ash aerosol in rats.

Inhalation studies were carried out with rats exposed to coal fly ash for 12 months. The main aim was to elucidate the factors that influence the accumulation of particles in the lungs during chronic exposure. Experimental results show that the particles of less than 2.3 micron can be transported to the bronchopulmonary lymph nodes by one of the clearance mechanisms.