2.3.1 The maximum specific optical density of
smoke (Ds max) shall be obtained for each test in accordance
with paragraph 9 of appendix 1 to this part.
2.3.2 When making toxicity measurements, the sampling
of fumes shall be made during the testing of the second and the third
specimen at each test condition, from the geometrical centre of the
chamber at the time when the maximum specific optical density of smoke
is reached. The concentration of each toxic gas shall be determined
as parts per million (ppm) in the chamber volume.