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Estimating the lung deposition of particulate polycyclic aromatic hydrocarbons associated with multimodal urban aerosols

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Title Estimating the lung deposition of particulate polycyclic aromatic hydrocarbons associated with multimodal urban aerosols
 
Creator VENKATARAMAN, C
RAYMOND, J
 
Subject size distributions
air-pollution
atmospheric aerosols
respiratory-tract
elemental carbon
mortality
models
california
particles
airways
 
Description Recent epidemiological evidence of associations between increased mortality and ambient particle concentrations suggests that ultrafine particles (smaller than 1 mu m diameter) and their constituents are potentially significant contributors because of their enhanced toxicity and their potential for greater lung penetration. Measurements of size distributions of potentially carcinogenic polycyclic aromatic hydrocarbons (PAH) in urban aerosols show their predominance in ultrafine and fine modes centered about 70 and 700 nm. In this article we present estimates of the regional lung deposition of PAH associated with a typical multimodal urban aerosol and examine the effect of varying size distribution characteristics on lung deposition. Size-dependent deposition fractions, from a deterministic calculation using deposition probabilities in a lung anatomical model, have been combined with the fraction of aerosol or PAH mass present in each particle size range and integrated over the entire size range to obtain the fraction of pollutant mass deposited in each lung region and the total lung. For typical urban aerosols the fraction of aerosol mass deposited ranges from 0.48 to 0.56 in the total lung, with 0.20 to 0.26 in the pulmonary lung and 0.28 to 0.30 in the tracheobronchial lung. For associated PAH the fractional mass deposited ranges from 0.27 to 0.32 in the total lung with a large fraction (0.23-0.28) in the pulmonary lung and 0.04 to 0.05 in the tracheobronchial lung. The fraction deposited is relatively invariant with varying size distribution characteristics like mass median diameter and mass fraction in each mode, making it possible to generalize the results to most locations. Exposure in a polluted urban air basin like the Los Angeles basin, with average PM-TO concentrations from 47 to 87 mu g m(-3) and particulate PAH concentrations from 0.1 to 3 ng m(-3), would result in average daily exposures to PM-10 and PAH, respectively, of 402 mu g h m(-3) and of 9.0 ng h m(-3). Resulting average daily doses, calculated from the lung deposition estimates, are 294 mu g day(-1) and 3.3 ng day(-1), respectively, of aerosol and PAH mass deposited in the total lung with 142 mu g day(-1) and 2.9 ng day(-1), respectively, in the pulmonary lung and compare with doses from sidestream environmental tobacco smoke (ETS) exposure in smoking areas. While it is difficult to interpret the toxicological implications of this dose, these calculations indicate high pulmonary deposition and the risk of delivery of carcinogenic PAH in ambient aerosols directly to the long interstitium. This reiterates the need for detailed study of ultrafine atmospheric aerosols and their toxic constituents in various microenvironments in which population exposures occur.
 
Publisher TAYLOR & FRANCIS INC
 
Date 2011-08-30T17:12:52Z
2011-12-26T12:59:04Z
2011-12-27T05:49:57Z
2011-08-30T17:12:52Z
2011-12-26T12:59:04Z
2011-12-27T05:49:57Z
1998
 
Type Article
 
Identifier INHALATION TOXICOLOGY, 10(3), 183-204
0895-8378
http://dspace.library.iitb.ac.in/xmlui/handle/10054/12403
http://hdl.handle.net/10054/12403
 
Language en