678e89c5___CTBTO_Preparatory_Commission__Health_hazards
[Radionuclide] Xenon (Xe) [Half-life*] 6.7 hours [Health hazards] 
Inhalation in excessive concentrations can result in dizziness, nausea, vomiting, loss of consciousness, and death. At low oxygen concentrations, unconsciousness and death may occur in seconds without warning.
General overview of the effects of nuclear testing: CTBTO Preparatory Commission
Health hazards