There is no oxygen in space, the only foreign substance your likely to come across are gamma rays from the sun, or foreign planets. If in bare space, the side of your body pointing towards the sun...
o2 or oxygen
They breath in oxygen and breath out carbon dioxide, like a human through it's lungs
Breathe in air ,mainly Nitrogen80% and 20% Oxygen Breathe out Carbon dioxide and Nitrogen
carbon dioxide is released into the air.