The elephant in the room are, as always, nitrous oxides (NOx).
Whenever you burn something in a nitrogen atmosphere, NOx are created. They contribute to acid rain and the formation of smog, and are a trigger for asthma.
Whenever you burn something in a nitrogen atmosphere, NOx are created. They contribute to acid rain and the formation of smog, and are a trigger for asthma.
Yes, it's an environmental concern for other reasons, but focusing on greenhouse considerations is fairly reasonable.