Which environmental conditions are necessary for alveoli and lungs to work well?

The alveoli need to be moist. Cold air is relatively dry air and breathing through the nose supposedly adds moisture. That is one of the theories why Neanderthals are thought to have had large noses.

You could expand on the logic of the nose breathing helping by increasing humidity. There could be more sinuses and more moisture added as air is breathed in. It probably also helps by warming the air.

The alveoli need to be moist. Cold air is relatively dry air and breathing through the nose supposedly adds moisture. That is one of the theories why Neanderthals are thought to have had large noses.