title: Total deposition of ultrafine sodium chloride particles in human lungs.
abstract: The total deposition of monodisperse, 0.026-0.19 micron (dry volume equivalent diameter) sodium chloride particles in the lungs of five healthy subjects, who breathed orally, was measured. For a tidal volume of 1,000 ml and flow rate of 500 ml/s, the percentages deposited were: 37.2 +/- 8.4% (mean +/- SD) for 0.026 micron, 23.8 +/- 3.3% for 0.051 micron, 22.8 +/- 3.1% for 0.096 micron, and 31.8 +/- 6.2% for 0.19 micron particles. The deposition minimum corresponded to a particle size of approximately 0.08 micron. Deposition did not correlate with measures of lung volume or body size but did correlate with forced expired flow rate after 75% of forced vital capacity (FVC) exhaled (FEF 75%/FVC) and with percent-predicted values for FEF 25-75% and FEF 75%. Lengthening the breathing period from 4 to 8 s/breath while maintaining flow rate at 500 ml/s caused an additional 11.3 +/- 3.1% of the inhaled particles to deposit. Sedimentation and diffusion were found to be the principal deposition mechanisms. These hygroscopic particles deposited according to sizes they would attain in air with a relative humidity between 96 and 100%.
mesh_terms: D000328:Adult; D000336:Aerosols; D001834:Body Water; D055598:Chemical Phenomena; D002621:Chemistry; D005260:Female; D006801:Humans; D008168:Lung; D008297:Male; D010316:Particle Size; D012119:Respiration; D012965:Sodium Chloride / Q000008:administration & dosage*; D012995:Solubility; D013997:Time Factors; D014018:Tissue Distribution
chemical_list: D000336:Aerosols; D012965:Sodium Chloride