title: Intermittent exposures to mixed atmospheres of nitrogen dioxide and sulfuric acid: effect on particle clearance from the respiratory region of rabbit lungs.
abstract: Nitrogen dioxide (NO2) and sulfuric acid (H2SO4) are important constituents of the gas-particle complex in ambient air. The purpose of this study was to examine the effects of combined exposures upon the clearance of insoluble tracer particles from the respiratory region of the lungs. Rabbits were the animal model, and were exposed for 2 h/day for 14 days to either 0.3 ppm NO2, 1 ppm NO2, or 500 microgram/m3 H2SO4 alone, or to mixtures of the low and high NO2 concentrations with acid. Inhaled singly, both concentrations of NO2 accelerated clearance while H2SO4 retarded it, compared to control. Exposure to the combination of 0.3 ppm NO2 plus H2SO4 resulted in a response which was not different from that due to the acid alone. However, exposure to 1 ppm NO2 plus H2SO4 resulted in a clearance pattern which differed from that of both NO2 and H2SO4, but was more similar to that of the latter.
mesh_terms: D000336:Aerosols; D000393:Air Pollutants / Q000633:toxicity*; D000818:Animals; D008168:Lung / Q000187:drug effects* / Q000276:immunology; D008297:Male; D009585:Nitrogen Dioxide / Q000633:toxicity*; D011817:Rabbits; D013464:Sulfuric Acids / Q000633:toxicity*
chemical_list: D000336:Aerosols; D000393:Air Pollutants; D013464:Sulfuric Acids; C033158:sulfuric acid; D009585:Nitrogen Dioxide