AAAR 34th Annual Conference
October 12 - October 16, 2015
Hyatt Regency
Minneapolis, Minnesota, USA
Abstract View
Unified Predictive Model for Particle Deposition in the Respiratory Tract
CHONG KIM, Shu-Chieh Hu, USEPA
Abstract Number: 531 Working Group: Health Related Aerosols
Abstract Particulate matter in the air is known for causing adverse health effects and one of the key factors for such effects is the deposition dose in the lung. Particle deposition in the lung is determined primarily by particle size and breathing pattern (tidal volume and breathing frequency, or flow rate/respiratory period) besides lung morphology. In the past, lung deposition data was analyzed without a full consideration of breathing pattern and as a result, deposition data showed a wide scatter at a given particle size and derived empirical relationships were under subject to large uncertainties. In the present study we compiled in vivo experimental data for both ultrafine and micron sized particles in normal adults and analyzed the data to derive a single expression for each of total and regional deposition as a function of both particle size and breathing patterns. Deposition was expressed by combination of two composite parameters; X1= (DTm)^p.Vt^q for ultrafine particles and X2= dp^m.Q^n.Vt^s for micron particles. Here, D is diffusion coefficient, Tm is mean respiratory time, Vt is tidal volume, dp is particle diameter, Q is mean respiratory flow rate. We found that total deposition fraction (TDF) can be expressed by a single function in the form of TDF = 1-1/(1+aX1 + bX2). Extrathoracic (ET) and tracheobronchial (TB) deposition can also be expressed with similar functions. Alveolar deposition then is obtained by AL = TDF-(ET+TB). Therefore, both total and regional deposition values can be estimated for a wide range of exposure conditions using four simple empirical equations. This is particularly useful when or where mathematical models are not available or inaccessible. This is an abstract of a proposed presentation and does not necessarily reflect EPA policy.