Verb
outgas (third-person singular simple present outgases or outgasses, present participle outgassing, simple past and past participle outgassed)
To release gaseous substances into the air, especially of a polymer material as it is aged or heated.
So above 550 °C, calcium carbonate begins to outgas CO 2 into air. Source: Internet
When such oxygen sinks became saturated, free oxygen began to outgas from the oceans 3–2.7 billion years ago, reaching 10% of its present level around 1.7 billion years ago. Source: Internet