Table 5-1. Compartments of the Respiratory Tract Model

DOE-HDBK-1184-2004

particle dissolution model; and

dosimetric model.

The respiratory tract is divided into the thoracic and extra-thoracic (ET) regions,

which are divided further into compartments that are used in the deposition and

clearance models. These compartments are listed in Table 5-1. Comparing the

regions of the ICRP 66 and ICRP 30 respiratory tract models, the ET region

corresponds to the nasal passage (NP) region, the BB and bb regions correspond

to the trachea and bronchial tree (TB) region, and the AI region corresponds to the

pulmonary parenchyma (P) region.

The deposition model describes quantitatively where inhaled particles will be

deposited in the different regions of the respiratory tract. The sites of initial particle

deposition are all the compartments listed above except for the thoracic and extra-

thoracic lymph nodes. Although it is possible to calculate deposition fractions from

first principles, in practice we usually obtain the fractions from published tables like

Table 5-2 below. These deposition fractions for occupational exposure were taken

from the ICRP-CD3.

Table 5-1. Compartments of the Respiratory Tract Model.

Extra-thoracic

ET1

Anterior nose

ET2

Posterior nose, larynx,

pharynx, mouth

ETseq

sequestered particles

LNet

extra-thoracic lymph nodes

Thoracic

BB - bronchial region

BB1 - fast clearing compartment

BB2 - slow clearing compartment

BBseq - sequestered particles

bb - bronchiolar region

bb1 - fast clearing compartment

bb2 - slow clearing compartment

bbseq - sequestered particles

AI - alveolar -interstitial region

AI1- fast clearing compartment

AI2 - moderate clearing compartment

AI3 - slow clearing compartment

LNth - thoracic lymph nodes

The ICRP Database of Dose Coefficients for Workers and Members of the General Public, Version 1.0 (Pergamon

Press: New York) 1998.