There us no such thing as carbon dioxide poisoning. Carbon dioxide is
normally produced as a by-product of metabolism and is largely eliminated
through the lungs by breathing. Its level in healthy people is the chief
determinant of repiratory rate. An acutely high level indicates respiratory
failure. A chronically high level suggests severe chronic lung disease.
Neither are caused by the nebuliser.

Are you thinking of carbon monoxide poisoning ? This is from faulty heaters
and poor ventilation and also has nothing to do with a nebuliser.