An electrically-powered device intended to measure nitric oxide (NO), also known as nitrogen monoxide, in exhaled air to facilitate diagnosis and management of asthma. Measurements are used to calculate fractional exhaled nitric oxide (FeNO) at different levels of the respiratory tract (e.g., bronchial, alveolar, nasal). It typically consists of a software-controlled, electronic unit and an attached tube for collection of expired air. It may also provide spirometry measurements.