To ensure better deposit of drugs in nasal cavity other than lung, nasal products such as nasal sprays generate particles with aerodynamic diameters mostly between 20-200μm. However, nasal sprays generate some (often <5%) particles <10μm, these tiny particles can penetrate the lower respiratory tract or lung. It is therefore important to quantify this fine particle dose (FPD) generated by nasal sprays. Cascade impactors (NGI, ACI) are used to capture 0-10μm particles. The combination of cascade impactor with nasal spray expansion chamber is used to measure fine particle doses of drugs in nasal sprays and nasal aerosols.