A nasal distribution device for a nasal airway of a subject includes: a mouthpiece (119; 219; 319; 419; 519; 619; 919) through which the subject in use breathes to cause closure of the oropharyngeal veil of the subject; a nasal mouthpiece (117; 217; 317; 417; 517; 617; 917) to fit a mouthpiece of a subject, the nasal mouthpiece (117; 217; 317; 417; 517; 617; 917) including a mouthpiece (149 ; 249; 349; 459; 549; 649; 949) through which the substance is in use distributed to the nasal airway; and an element of the body (121; 223; 321; 421; 521; 621; 921) that receives a substance supply unit (120; 220; 320; 420; 520; 620; 920), in which the element of the body (121; 223; 321; 421; 521; 621; 921) includes an inlet (325; 525; 625; 925) that is in fluid communication with the nozzle (119; 219; 319; 419; 519; 619; 919 ) and an outlet (327; 527; 627; 927) that is in fluid communication with the nasal nozzle (117; 217; 317; 417; 517, 617, 917); characterized by: a manually operable substance supply unit (120; 220; 320; 420; 520; 620; 920) to distribute the substance through the nozzle (149; 249; 349; 459; 549; 649; 949) , of the nasal nozzle (117; 217; 317; 417; 517; 617; 917), where the substance distribution unit (120; 220; 320; 420; 520; 620; 620; 920) is composed of a part of the body (355; 655; 955) which is movable from a first, resting position to a second, activated position of manual activation of the substance distribution unit (120; 220; 320; 420; 520; 620; 920), and the entrance (325; 525; 625; 925) to the body element (121; 223; 321; 421; 521; 621; 921) is open when the body part (355; 655; 955) of the distribution unit of substance (120; 220; 320; 420; 520; 620; 920) moves to the drive position, therefore providing an air flow through the nasal nozzle (117; 217; 317; 417; 517; 617; 917) simultaneously with the manual activation of the substance distribution unit (120; 220; 320; 420; 520; 620; 920).Un dispositivo de distribución nasal para una vía aérea nasal