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Respiratory Deposition

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  1. Respiratory Deposition Reading: Chap 11 • Health hazards caused by inhaled aerosols depend on their chemical composition and on the site at which they deposit within the respiratory system • Effective medicine delivery by the aerosol route also relies on knowledge of aerosol deposition in our respiratory system Respiratory System • Head airways region – includes nose, mouth, pharynx and larynx • Lung airways or tracheobronchial region – includes the airways from the trachea to the terminal bronchioles • Alveolar region – gas exchange takes place Aerosol & Particulate Research Lab

  2. Head Airways Lung Airways/ Tracheobronchial region Alveolar/Pulmonary Region Aerosol & Particulate Research Lab

  3. Characteristics of Selected Regions of the Lung Q: What are the important mechanisms for respiratory deposition of aerosols? Aerosol & Particulate Research Lab

  4. Mechanisms - Impaction : airway wall Q: When is impaction important? - Settling : bronchi, bronchioles - Condensation: hydroscopic materials - Diffusion: the smaller particles Q: What are the other factors that may affect deposition? Q: How does the total deposition efficiency vs particle size look like? Aerosol & Particulate Research Lab

  5. Deposition Models • ICRP (International Commission on Radiological Protection) • NCRP (National Council on Radiation Protection and Measurement) Aerosol & Particulate Research Lab

  6. Regional Deposition Aerosol & Particulate Research Lab

  7. Inhalability of Particles • Inhalable Fraction – the fraction of particles originally in the volume of air inhaled that actually enters the nose or mouth (ACGIH criterion) Q: What is the criterion for a good inhalable sampler? Respirable Fraction Q: Does a concentration lower than the inhalable criterion guarantee our health safety? • Because of the size-selective characteristics of the human respiratory system, particles larger than a certain size can’t reach the alveolar region – these are considered non-harmful to alveolar injury Aerosol & Particulate Research Lab

  8. Thoracic Fraction • TF – the fraction of ambient aerosol particles that will pass beyond the larynx and reach the thorax or chest during inhalation TF=(IF)(1-exp(-exp(2.55-0.249da)) Q: PM10 vs TF – can a PM10 sampler be used for TF sampling? Q: PM2.5 vs RF – can a PM2.5 sampler be used for RF sampling? Q: What is the criterion for a good inhalable sampler? Aerosol & Particulate Research Lab

  9. Aerosol & Particulate Research Lab

  10. Science dessert • Cognitive-Enhancing Nasal Spray: interleukin-6 administered through the aerosol route helps brain retain memory during sleep. No need to stay over night! • Le Whifs Breathable Coffee & Chocolate – aerosolized flavor powder to indulge gourmet flavors without gaining weight http://pubs.acs.org/cen/newscripts/87/8742newscripts.html http://hubpages.com/hub/Le-Whifs-Breathable-Coffee-and-Chocolate Aerosol & Particulate Research Lab

  11. Reflection Aerosol & Particulate Research Lab