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Comparison of particle lung doses from the fine and coarse fractions of urban PM-10 aerosols

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Title Comparison of particle lung doses from the fine and coarse fractions of urban PM-10 aerosols
 
Creator VENKATARAMAN, C
KAO, AS
 
Subject size distributions
deposition calculations
respiratory-tract
air-pollution
airways
models
mortality
 
Description The U.S. Environmental Protection Agency (EPA) recently revised the national ambient air quality standards to include a new PM-2.5 particulate standard. We examine the contributions of fine (PM-2.5) and coarse (PM-2.5 to -10) fraction of typical urban aerosols to particle doses in different lung airways resulting from 24-h exposure to the standard concentration of 150 mu g m(-3). The aerosol is assumed to have a bimodal lognormal mass distribution with mass median diameters of 0.2 and 5 mu m, and geometric standard deviation of 1.7 and 57% of the mass in the fine (PM-2.5) mode. The daily mass dose from exposure to 150 mu g m(-3) of PM-10 in the nasopharyngeal (NPL) region is 20-51 mu g day(-1) (7.5% of inhaled fines) and 377-687 mu g day(-1) (30% of inhaled coarse), respectively, of fine and coarse mass filtered in the nose. Similar daily mass doses from fine and coarse fractions, respectively, to the tracheobronchial (TBL) region are 28-38 (1.5%) and 40-52 (4%) mu g day(-1) and to the pulmonary (PUL) region are 18-194 (6%) and 32-55 mu g day(-1) (2%). The daily number dose in the NPL region is 5-15 x 10(8) (0.06% of inhaled fines) and 5-10 x 10(6) day(-1) (13% of inhaled coarse) respectively, of fine and coarse particles. Similar number doses to the TBL region are 2.2-3.1 x 10(10) (2%) and 7.1-11.1 x 10(5) (2%) day(-1) and to the PUL region are 1.6-16.7 x 10(10) (9%) and 2.9-17.0 x 10(5) (3%) day(-1). The daily surface mass dose (mu g cm(-2) day(-1)) from coarse fraction particles is large in generations 3-5. The daily number dose (particles day(-1)) and surface number dose (particles cm(-2) day(-1)) are higher from the fine than the coarse fraction, by about 10(3) to 10(5) times in all lung airways. Fine fraction particles result in 10,000 times greater particle number dose per macrophage than coarse fraction particles. Particle number doses do not follow trends in mass doses, are much larger from fine than coarse fraction, and must be considered in assessing PM health effects. For the assumed fine fraction ratio of 0.57, the estimated increase in protection from the new PM-2.5 standards is a 25% and 47% lower dose, respectively, at the 24-h and annual standard in comparison with the respective PM-10 standards. The mass fraction in the fine mode depends upon the local sources, will vary with different extents of control of various source types, and will influence the choice of control strategy to meet the revised standard.
 
Publisher TAYLOR & FRANCIS INC
 
Date 2011-08-30T16:39:08Z
2011-12-26T12:59:03Z
2011-12-27T05:49:56Z
2011-08-30T16:39:08Z
2011-12-26T12:59:03Z
2011-12-27T05:49:56Z
1999
 
Type Article
 
Identifier INHALATION TOXICOLOGY, 11(2), 151-169
0895-8378
http://dx.doi.org/10.1080/089583799197221
http://dspace.library.iitb.ac.in/xmlui/handle/10054/12394
http://hdl.handle.net/10054/12394
 
Language en