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ANALYSIS OF TOTAL RESPIRATORY DEPOSITION OF INHALED ULTRAFINE PARTICLES IN ADULT SUBJECTS AT VARIOUS BREATHING PATTERNS
Citation:
Kim, C. S. AND P. Jaques. ANALYSIS OF TOTAL RESPIRATORY DEPOSITION OF INHALED ULTRAFINE PARTICLES IN ADULT SUBJECTS AT VARIOUS BREATHING PATTERNS. AEROSOL SCIENCE AND TECHNOLOGY. American Association for Aerosol Research, MT. LAUREL, NJ, 38:525-540, (2004).
Impact/Purpose:
To measure total respiratory tract deposition fraction (TDF) of inert ultrafine aerosols to assess a potential health risk to exposure to these particles.
Description:
Ultrafine particles are ubiquitous in the ambient air and their unique physicochemical characteristics may pose a potential health hazard. Accurate lung dose information is essential to assess a potential health risk to exposure to these particles. In the present study, we measured total respiratory tract deposition fraction (TDF) of inert ultrafine aerosols (NMD = 0.04, 0.06, 0.08, and 0.10 m and g 1.3) in a group of young healthy adults (11 males and 11 females). Six different breathing patterns were used: three different tidal volumes (Vt = 500, 750 and 1000 ml) and two different flow rates for each Vt. The mean respiratory time (Tm) ranged from 2 to 4 s. It was found that TDF increased with a decrease in particle size, thereby an increase in diffusion coefficient (D), and with an increase in Tm and Vt. For Vt = 500 ml, TDF ranged from 0.33 to 0.53 at Tm = 3.33 s and from 0.25 to 0.44 at Tm = 2 s for the range of NMD = 0.04 - 0.1 m. For Vt = 1000 ml, TDF ranged from 0.40 to 0.66 at Tm = 4 s and decreased to the range of 0.29 - 0.54 at a smaller Tm of 2 s. TDF was slightly greater in female vs. male subjects for only small ultrafine particles ( ie., NMD = 0.04 m) at the same breathing pattern. When TDF values were plotted against a composite parameter, (DTm)0.5Vt0.75, all data were consolidated by a single curve ( 2 = 0.94). The results show that TDF of ultrafine particles can be reliably estimated by unique empirical formula and this provides a convenient means of assessing respiratory dose of ultrafine particles.