A breath analyzer is described with at least one chemical sensor sensitive to the concentration of a component in a sample of exhaled breath including a compensator for compensating for the effect of variations in the amount of exhaled breath between the user and the sensor location with the chemical sensor being integrated into a portable electronic device, particularly with the sensor being located in an air duct with an opening to the exterior of the housing of the analyzer with the total area of the opening being sufficiently small to restrict effectively mass transport between the exterior and the sensor and/or wherein the compensation includes the compensation for different responses of sensors.