ABSTRACT
Many epidemiological studies indicated associations between ambient particulate matter (PM) air pollution and increased cardiopulmonary mortality. This suggested that exposure to particulate matter below the PM10 standards may adversely affect human health. We hypothesize that enhanced regional particle deposition dose ('high dose') in the human lower airways ('long-term-retaining' compartments) is an underlying factor for such a finding (and this hypothesis is consistent with experimental observations in animals). Various mechanisms of enhanced fine particle deposition may simultaneously exist, substantially increase the local particle deposition dose, and initiate or aggravate the acute and chronicle lung diseases. The degree of the enhancement is sensitive to the age, gender, health condition and activity level as a function of airway morphology, airway dimension, particle sizes and ventilation parameters. The objective of this project is to investigate when, where, why these particle deposition 'hot spots' are formed and what are the implications to the inhalation toxicology and aerosol therapy.
This research is being conducted using the cost effective in-vitro experiments and computer simulations. The simulated elastic respiratory bronchioles and alveolar duct models are made of latex rubber using successive dipping method. Volume expansion and contraction of the hollow latex models are controlled by varying the air pressure inside the vacuum chamber. The overall and local particle deposition patterns in the airway models will be measured. Computer simulations of air flow and particle deposition patterns with the effects of 3-D moving-boundary geometry will be conducted in a wide range of parameters. Numerical results will be verified by the experimental measurements.
The research has important applications in inhalation toxicology, aerosol medicine delivery, aerosol-based diagnostic methods, gene therapy, and understanding basic biological processes. It is expected that at the completion of the project, we will have a better understanding of the mechanisms of the site-specific high-dose particle deposition. An improved interspecies extrapolation theory of PM pulmonary deposition will be developed. The sub population that may be at increased risk in terms of higher initial lung deposition from the pollutant PM can be identified. Results of this research can be extended to the applications of gas transporting process within the human lower airways.
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Biofluids and Heat Transfer Laboratory
Mechanical Engineering and Applied Mechanics
University of Rhode Island