A nasal filter (1) comprising a frame (2) with a right and a left frame portion (2a, 2b) dimensioned for placement inside a left and right nostril, respective, and optionally connected via a U-shaped bridge (4). Each frame portion (2a, 2b) comprises an anterior support section (6a) towards the front of the nose and a posterior support section (6b) towards the back of the nose, the support sections supporting a filter element (3). Resilient means (8′,9′) connect the anterior support section (6a) with the posterior support section (6b) for flexible change of distance between the anterior support section (6a) and the posterior support section (6b).