Asphyxiant Posted on 2nd November 201517th July 2021 by ThePD (The Project Definition) An Asphyxiant is a vapor or gas substance which can cause unconsciousness or death by suffocation (lack of oxygen). Click to share on Twitter (Opens in new window)Click to share on Facebook (Opens in new window)Click to share on LinkedIn (Opens in new window) Related Posted in Substance and tagged health, hydrocarbon, substance. ThePD (The Project Definition) ThePD has been developing the Preferred Project Definitions based on the actual project execution and operation experiences and knowledge with the Project Language, and sharing with you daily basis.