Size distribution of exhaled particles in the range from 0.01 to 2.0 μm

• Published in: Journal of aerosol science Vol. 41; no. 5; pp. 439 - 446
• Main Authors: Holmgren, Helene, Ljungström, Evert, Almstrand, Ann-Charlotte, Bake, Björn, Olin, Anna-Carin
• Format: Journal Article
• Language: English
• Published: Oxford Elsevier Ltd 01.05.2010; Elsevier
• Subjects: Aerosols; Airway closure; Biological and medical sciences; Chemistry; Colloidal state and disperse state; Exact sciences and technology; Exhaled particles; General and physical chemistry; Medical sciences; Pneumology; Size distribution; Tidal breathing; Airway closure; Tidal breathing; Size distribution; Exhaled particles; Film; Time; Droplet; Mechanism; Inhalation; Particle; Generation; Individual; Distribution; Formation
• ISSN: 0021-8502; 1879-1964
• DOI: 10.1016/j.jaerosci.2010.02.011

This study investigates the number size distribution of endogenously produced exhaled particles during tidal breathing and breathing with airway closure. This is the first time that the region below 0.4 μm has been investigated. The particle concentration was generally lower for tidal breathing than for airway closure, although the inter-individual variation was large. During tidal breathing, the size distribution peaks at around 0.07 μm. This peak is still present during the airway closure manoeuvre, but an additional broad and strong peak is found between 0.2 and 0.5 μm. This suggests that different mechanisms govern the generation of particles in the two cases. The particles produced from airway closure may be attributed to formation of film droplets in the distal bronchioles during inhalation. It is speculated that the very small particles are film droplets originating from the alveolar region.