Exhaled acetone dependency on inhalation Exhaled concentration of inert gases simply depends on the inhaled concentration. Especially in steady state it is obvious that exhaled concentration needs to be equal to the inhaled concentration. In the case of volatile organic compounds (VOCs) that take part in the metabolism the relationship becomes more complicated. The exhaled concentration then also depends on metabolic production and metabolization rates. We consider the concentration in steady state. We already know that exhaled concentration is a linear function of inhaled concentration, fully described by two numbers - slope and intercept. Based on a PBPK model we derive the corresponding functions and discuss the influence of physiological parameter on these numbers. We also intend to estimate these parameter based on recorded measurements.