From El Pais

Scientists are investigating why this well-known chasm has suddenly run out of oxygen

http://elpais.com/elpais/2017/01/02/inenglish/1483355787_076581.html

They seem to be muddling the effects of high carbon dioxide and low oxygen  levels  up. Rapid breathing is a symptom produced by high CO2 levels. However clearly the oxygen is being depleted as well but normally a low oxygen level just causes you to gradually black out without even realising you are being affected. I suspect this is  more the journalists reporting the situation rather than the scientists involved in the investigation.