Aerosol Particles in Lungs
Dynamical Modeling of Composition Transformation and Deposition of Aerosol Particles in the Respiratory Tracts and Lungs
Tech Area / Field
3 Approved without Funding
Karpov Institute of Physical Chemistry, Russia, Moscow
- Institute of Numerical Mathematics, Russia, Moscow\nVNIIEF, Russia, N. Novgorod reg., Sarov\nA.I. Burnazyan Federal Medical and Biophysical Center, Russia, Moscow
- Fraunhofer Institute Toxikologie und Aerosolforschung, Germany, Hannover\nUniversity of Helsinki / Lahti Research and Training Center, Finland, Lahti\nState University of New York University at Buffalo, USA, NY, Buffalo\nMSA AUER GmbH, Germany, Berlin
Project summaryThe Project assumes the theoretical and experimental modeling of all transformation and deposition stages of airborne particles in respiratory tracts and lungs.
Natural and anthropogenic aerosols are known to affect the human health mainly by hitting the internal parts of the lung tracts. The penetration of the aerosol particles in lungs is stipulated by a number of aerosol processes which, in turn, depend on the particle sizes and chemical content. These processes are:
- Transport of the aerosol particles inside the lung tracts,
- Growth of the particles (by condensation, coagulation) in the humid atmosphere of the respiratory lung tracts,
- Particle diffusion and inertial deposition on the walls of the lung tracts.
Within the Project the kinetics and dynamics of the condensation growth of aerosol particles will be studied. The most important point of this block is the study of the dependence of the condensation growth rate on the particle size and chemical content of the aerosol particles. The periodic changes of the growth condition modeling the breath are assumed to be included in the model. Different regimes of condensation (free molecular, transition and continuous ones) are supposed to be investigated theoretically and experimentally. To this end special aerosol generators are supposed to be created producing the liquid and solid aerosol particles of sizes within 10-1000 nm (spherical, nonspherical and aggregated particles). The experiments on particle growth are planned to be performed in a specially designed cell in which the humidity and temperature will change periodically within the interval -20 - +30 C. The experimental results will be compared with the predictions of the theoretical models sped ally formulated for the periodically varying external conditions. The data thus obtained will be used in the transport models.
Modeling of the aerosol transport through pipes of various diameters and shapes, including ramified tracts is assumed to perform within the Project. The external param-eters of the flow are planned to vary in the wide range (temperature from -20 to +30° C, the linear flow rate up to 1 m/s, flow oscillation frequency up to 1Hz, relative humidity from 0 % up to 100 %. The differential penetration ratio (number concentration of the inletting aerosol to that of outletting aerosol of a given size and content) is assumed to be measured and compared with the prediction of the theoretical models (see next Sections).
The deposition is the most important process defining the aerosol effect on human health. The rate of deposition depends on all above mentioned aerosol parameters (par-ticle size and composition distribution of aerosols), thermo-hydrodynamic regimes of flow and lung tracts wall conditions. Smaller aerosol particle deposition is defined by its diffusion to the walls in the humid atmosphere of the lung tracts. Bigger particles deposit owing to their inertia and this process thus depends on the channel shape. The complex of these processes is planned to study theoretically and experimentally. The experimental setup will include the aerosol generators connecting with the set of pipes modeling the lung tracts. Total and differential penetrations will be measured with the aerosol spectrometers specially designed for this work. Several substrates are assumed to settle along the pipes in order to measure the deposition rate at different parts of the channel. The results of measurements will be compared with the theoretical predictions based on numerical model of the particle motion inside the lung tracts, The numerical model assumed to be created within the Project is based upon the transport equations (thermo-hydroaerodynamic set of equations) taking into account the aerosol processes: their passive transport, diffusion, condensation, coagulation, the wetting of particles and their inertial deposition.
Input parameters of the model are:
Temperature, air pressure of the, flow rate, the frequency of breath, aerosol particle size and composition distribution and concentration.
Total and differential penetration, the distribution of the deposit over the channel length, particle size and composition distribution of the deposit in different parts of respiratory tracts and lungs.
The transport equations will be solved analytically and numerically and the deposition rate at the different parts of the channel be defined and compared with the experimental data.
The final output of the Project will be the computer codes for determination of the differential penetration of the aerosols passing the channels modeling the lung tracts and allowing the deposit distribution over the lung tracts to be restored. These programs will be used for recommendations in different cases (normal regime and accidents).