Which of the following gases is non-poisonous?

Oxygen (O2) is considered a non-poisonous gas that is essential for life. It's a vital component of the air we breathe and is necessary for the process of respiration in humans and many other organisms. In the context of mining and rescue operations, oxygen is crucial as it supports combustion and is necessary for the survival of those involved in rescue efforts.

While carbon monoxide (CO), hydrogen sulfide (H2S), and ammonia (NH3) can all be hazardous to health—carbon monoxide is a toxic gas that can cause serious health issues, hydrogen sulfide is highly toxic and can be lethal even at low concentrations, and ammonia is irritating and can cause damage to respiratory organs—oxygen is safe under normal atmospheric conditions. In emergency situations, ensuring a supply of breathable oxygen is a key factor in protecting the safety and health of miners.