Questions/comments to EVS1542-502 (CN) Toxicity always has to be assessed as a combination of substance and dose, i.e. realistic concentration and time of exposure to potentially harmful substance. Exposure requirements are only required if it can be shown that there is a realistic risk of exposure (time and concentration) of vehicle occupants above hazardous levels in the event of a field incident. What scenarios have been identified where there is a realistic risk of harmful exposure? What strategies to minimize risk of exposure of vehicle occupants have been considered, e.g. dedicated gas evacuation channels, strategies to remove toxic species from vented gases, etc.? The effects of exposure can be mitigated by effective antidotes to hazardous substances, e.g. calcium gluconate for HF exposure. How does identification of effective antidotes affect the assessment of risk to vehicle occupants? Comments Gas detection and toxicity assessments have to be made in a realistic environment since the conditions of test has a significant impact on the outcome of the test, both in terms of the chemical species that can form and their relative concentrations