Abstract: Device (10) may be inserted in a nostril to filter and/or sample air inhaled or exhaled. Air inhaled through device (10) enters aperture (21) and exits through aperture (25). While passing through device (10) the airstream is deflected around deflector (16) and caused to encounter collector (19) extending inwardly from sidewall (18). A liquid or adhesive on collector (19) entraps particles, e.g. allergens, in the airstream, and can be subsequently removed for analysis. Alternatively collector (19) can be replaced by a reservoir for delivery of a pharmaceutical to a subject by inhalation.