Table 7.

Respiratory tract dosimetry model parameters for acetaldehyde, acrolein, and diacetyl and model predictions for human bronchiolar concentrations.

Property	Acetaldehyde	Acrolein	Diacetyl
Diffusivity in air (cm2/s)	0.128	0.105	0.091
Diffusivity in water (cm2/s)	1.35E-05	1.22E-05	4.30E-06
Tissue:air partition coefficient	140	88	572
First order constant, Kp (1/s)	0.0357	0.05	0.005
Saturable pathway constant, Km (ug/L)	1320	0.5	861
Saturable pathway rate constant, Vmax (ug/m3/s)	<1.0E-08	6.1E-07	0.964
Water solubility (g/L)	1000	212	200
Modeled concentration (ppm) in human bronchiolar epithelium with light exercise and mouth-only breathing at 1 ppm inhaled air concentration	74	0.0077	0.0077

Dosimetry model by Gloede and colleagues [35] for a mouth-breathing human under light exercise. Parameters for acrolein and acetaldehyde reported by Asgharian and colleagues [49] and for diacetyl as reported by Gloede and colleagues [35].