asphyxiant

Many residents were trapped on higher floors as it spread, and the inquiry found all the victims were dead or unconscious by the time the flames reached them due to "inhalation of asphyxiant gases", primarily carbon monoxide.

Phosgene, more deadly than chlorine, was also an asphyxiant—it too caused death by suffocation.

They also express concerns about the safety of storing large amounts of carbon dioxide, an asphyxiant, in a densely populated community.

Pipelines for CO2 transport the gas at high pressure and at a high enough concentration to make it an asphyxiant.

High concentrations of carbon dioxide, if it leaks out of pipelines or storage wells, can be an asphyxiant to people and wildlife.