The present invention provides an air-intake device for delivering a substance to the nasal cavity of a subject which comprises:a container for containing the substance; a nosepiece and a mouthpiece extending from the device, for placement in proximity to the nose and mouth of the subject, respectively;a valve mechanically connectable to the container, with an active configuration and an inactive configuration; and,a trigger mechanism to reconfigure the valve from the active configuration to the inactive configuration, and vice versa.