Too much humidity promotes bacterial growth. You're placing your animal in a damp warm condition. That's asking for the lungs to act like a giant petri dish.
There are different types or RI.
1) Bacterial
2) Fungal
3) Viral
If it's viral, there is no treatment.
Bacterial RI will need a culture to determine what kind of bacterial is affecting the lungs and which antibiotic can be used to treat it. Certain antibiotics are bacteria specific and will only affect that kind of bacteria. Most of the time Baytril does nothing these days except for damaging your snake's scales. Baytril tends to leave permanent burns and tissue necrosis.
If RI is caught early, there are chances the snake can recover on it's own w/ a bump in temps. But normally snakes will need medical treatment.
I would be weary citing Melissa Kaplan. She is well known for giving poor reptile advice.
Edit: Inarikins beat me the Kaplan thing.
And whoops x2 about posting on an old thread. Didn't realize it.