Peripheral	Airways and lung tissue beyond the subsegmental airways
Central	The central airways up to and including the subsegmental airways
xs, xsl	The subscript s indicates the value x changes with subject, and the subscript sl indicates that the value x changes with both subject and lobe
	The specific deposition in the periphery of a lobe, the subject average specific deposition, and the non-dimensional ratio of
	The specific ventilation of a lobe, the average specific ventilation of a subject, and the non-dimensional ratio of
	The escape fractions of aerosol passing location x in inhalation of the aerosol due to impaction, sedimentation, and diffusion
	The fraction of aerosol passing location x during inhalation of the aerosol that is not exhaled, that fraction for a given lobe, for a given subject, and the non-dimensional ratio of
	The retention factor of aerosol passing the carina along a pathway leading to a specific lobe, or to the entire lung
Cx, Csl, Ccarina,s	The concentration of the aerosol in air at: location x in the airway tree, entering into the periphery of a given lobe, passing the carina of a given subject
Dx, Vx	The cumulative aerosol that deposits past location x in the airway tree during inhalation, and the cumulative volume of air that passes that location during inhalation
Bk	The branching factor of airway k. Describes the change of concentration between the terminus of the parent airway and the airway entrance during inhalation if the aerosol
Ek	The escape fraction of airway k. Describes the change of concentration along an airway k during inhalation of the aerosol
	The net branching factor of a given lobe, the average for a subject, the ratio of , and this value estimated with complete retention
	The net escape fraction of a given lobe, the average for a subject, the ratio of and this value estimated with complete retention
	Factors of that independently effect and
tN,s	The nebulization time for a given subject
D0,s, DE,s, DT,s, DP,s, DC,s	The total aerosol arriving at the carina, the exhaled fraction, the total deposited, the peripheral deposition, and the central deposition of a given subject (with a subscript sl, it is of a given lobe)
	The total average rate and volume of gas passing the carina of a given subject during inhalation
VL,s	The subject lung volume
	The set of airways feeding a given lobe
S	The set of all lobes of all subjects
	The specific inflation of a lobe, the subject average specific ventilation, and the non-dimension ratio of the
MLV,TLC	The mean lung volume during tidal breathing, and total lung capacity
	The total change in gas volume from the MLV to TLC HRCT image
Ksl	A factor that accounts for segmentation differences and the change in blood volume between the MLV to TLC HRCT images
	The fraction of subjects ventilation reaching a given lobe
ds, vs, ts	The distance a particle would sediment, the settling velocity, and the settling time
QN	The inhalation flow rate
	The degree of expansion of a lobe (the gas volume/the non-gas volume)
	The gas and non-gas (tissue and blood) volumes estimated for a given lobe in the MLV image. A subscript of TLC indicates that this was taken from the TLC image, and a subscript of s (or T) indicates that is volume of the entire lung
fN	The breathing frequency of a given subject during inhalation
FEV1	Forced expiratory volume in 1 second after a deep inhalation
FVC	Forced vital capacity