A diffuser includes an air inlet for receiving an airflow from a hair dryer, a grille having a plurality of air outlets for emitting at least part of the airflow from the diffuser, a baffle having an outwardly tapering wall which defines a diffusing air chamber through which the airflow passes between the air inlet and the air outlets, and an external wall which surrounds the wall of the baffle to define a second air chamber therebetween. The second air chamber has a plurality of ports in fluid communication with the ambient atmosphere.