The guy who wastes too much oxygen

Oxygen, thank God, is still free here (for now...), but it still needs to be taken care of. Forests are being cut down, and there are more and more people on the planet. These cows... spoil the atmosphere with their "gases". They are responsible for 18% of all greenhouse gases in the world! Oh, those cows... And then there's this guy! He can breathe for 10 people, no less! You need to know when to stop...