An experimental study of clearance of inhaled particles from the human nose

Abstract

Retention in the extrathoracic airways, and clearance by nose blowing, of monodisperse indium-111-labeled polystyrene particles were followed for at least 2 days after inhalation by healthy volunteers. Nine volunteers inhaled 3-μm aerodynamic diameter particles while sitting at rest, whereas subgroups of 3 or 4 inhaled 1.5-μm or 6-μm particles at rest, and 3-μm or 6-μm particles while performing light exercise. Retention of the initial extrathoracic deposit (IETD) in the extrathoracic airways was described by 4 components: on average 19% IETD cleared by nose blowing; 15% was swallowed before the first measurement, a few minutes after inhalation; 21% cleared by mucociliary action between the first measurement and about an hour later; and 45% subsequently cleared by mucociliary action. Geometric mean times in which 50% and 90% of IETD cleared were 2.5 and 22 hours. The geometric mean retention fractions at 24 and 48 hours were 7% and 2.4% IETD, respectively. No clear trends were found between parameters describing retention and any related to deposition (e.g., particle size). However, the fraction cleared by nose blowing was related to the frequency of nose blowing and therefore appears to be a characteristic of the individual.

ICRP Publication 130: Occupational Intakes of Radionuclides: Part 1

“…It was assumed (Fig. A.1) that of material deposited in the ET airways, approximately 50% deposits in ET 1 , which is cleared by nose blowing at a rate of 1 d −1 , and the rest deposits in ET 2 , which clears to the gastrointestinal tract at a rate of 100 d −1 . (A12) In experiments intended to address this deficiency, subjects inhaled 1.5-, 3- or 6-µm aerodynamic diameter ( d ae ) radiolabelled insoluble particles through the nose while sitting at rest or performing light exercise (Smith et al., 2002, 2011). Retention in the nasal airways and clearance by voluntary nose blowing were followed until at least 95% of the initial ET deposit had cleared (typically approximately 2 d).…”

“… (A15) In the original HRTM, it was assumed that particles deposited in the nasal passages during inhalation are partitioned equally between ET 1 and the posterior nasal passage, which is part of ET 2 [however, because of the way the deposition efficiencies were calculated for polydispersed aerosols during inhalation and exhalation, for most aerosol sizes of interest in radiological protection, the deposition fractions given in Publication 66 (ICRP, 1994a) are somewhat higher for ET 2 than for ET 1 ]. In the revised HRTM, based on the recent experiments (Smith et al., 2011), it is assumed that for nose breathing, the deposit in the ET airways is distributed 65% to ET 1 and 35% to ET 2 . To calculate the fractions of inhaled material deposited in ET 1 and ET 2 in the revised HRTM, the fractions deposited in ET 1 and ET 2 (calculated using the original HRTM) were summed to give the total deposit in the ET airways, and then repartitioned 65% to ET 1 and 35% to ET 2 (for mouth breathing, there is no deposition in ET 1 , and the fraction deposited in ET 2 remains as calculated using the original HRTM). (A16) Table A.2 gives values of fractional deposition in each region of the respiratory tract as a function of aerosol size for (a) an adult male sitting at rest, (b) an adult male undertaking light exercise, and (c) the Reference Worker.…”

“…(A12) In experiments intended to address this deficiency, subjects inhaled 1.5-, 3or 6-mm aerodynamic diameter (d ae ) radiolabelled insoluble particles through the nose while sitting at rest or performing light exercise (Smith et al, 2002(Smith et al, , 2011. Retention in the nasal airways and clearance by voluntary nose blowing were followed until at least 95% of the initial ET deposit had cleared (typically approximately 2 d).…”

PM2.5 and Serum Metabolome and Insulin Resistance, Potential Mediation by the Gut Microbiome: A Population-Based Panel Study of Older Adults in China

“…Evidence from previous studies measured the percentage of inhaled particles in the lungs and characterized the translocation of particles from the respiratory tract ( Semmler et al. 2004 ; Smith et al. 2011 , 2014 ; U.S. EPA 2019 ).…”

Type 5 and 6 nasal septal deformities: Could we predict and prevent acute coronary syndrome attacks in the future?

“…Undisturbed nasal breathing is essential for normal breathing physiology as a whole and the effects of nasal obstruction on the respiratory and cardiovascular systems have been well studied: right ventricle problems 1,2 , ischemic heart diseases 3,4,5,,6,7,8,9 , sleep disorders 10,11,12,13 , mucociliary clearance system disturbances 14,15 , paranasal sinus pathology 16,17 , have all been described as a result of impaired nasal breathing. The connection between the upper and lower respiratory systems has been recognized in allergic rhinitis and asthma as well, resulting in united airways concept.…”