Hydrogen peroxide, especially in concentrations higher than those typically found in household solutions (which are typically 3%), can be highly irritating to the respiratory tract.
Nebulizing hydrogen peroxide can lead to inflammation of the airways, causing coughing, throat irritation, and potentially more severe respiratory distress.
Inhalation of vapors, mists, or aerosols from concentrated solutions of hydrogen peroxide can cause significant morbidity.
No odor threshold was located for hydrogen peroxide (the OSHA PEL is 1 ppm).