A previous deposition study with the tPAD, in six healthy adult subjects, demonstrated ~38% of the 7% HS aerosol emitted from the nasal cannula is deposited in the adult lungs, with no acute safety or tolerability issues (Parion Sciences Protocol PS-D100-102; Scott Donaldson, PI). This deposition efficiency matched that of the Pari LC Star used via the oral route, which was used as a standard of practice comparator. However, 7% HS nebulization by the tPAD resulted in a more peripheral deposition of the aerosol than the Pari LC Star comparator.