I don't think the ultrasonics should be a problem but humidifiers can increase the amount of mould and bacteria in the air. I don't have a humidifier although I do have an air purifier (Heaven Fresh XJ-3800 ) which cleans the air and traps dust.
Somewhere in another universe, dear brother, you got saved.
I was told by my avian vet that African greys do better with dry air. Since I live in the Pacific Northwest, where the air has a lot of humidity, I was concerned when Manfred got sick. She said the moist air could possibly be a concern with African Greys.