Chemicals entering the lungs in the venous blood stream can be
transferred to lung air and be exhaled. This transport term is opposite
of the inhalation and absorption process and works to remove
chemicals from the blood stream. It works well for removing
chemicals with a sufficiently high vapor pressure that are not accumulated in tissues such as body fat (Eq. (4)). The latter is
expressed by the accumulation ratio (KTA), which reflects the affinity
of substances for different body compartments, including neutral and
polar lipids, protein fractions and water.