A method of assessing the suitability of a metered dose inhaler actuator A test canister equipped with a valve and containing a pressurized propellant is provided. One or more actuators manufactured for use in a metered dose inhaler is provided and tested, wherein each actuator is tested by coupling the canister to the actuator, positioning the actuator with respect to an electrostatic measurement device and firing the canister such that electrostatic charge from an aerosol emitted by the canister is measured by the electrostatic measurement device. The measured electrostatic charge is compared to a predetermined specification range to make a determination whether the measured electrostatic charge is within or outside the predetermined specification range and accordingly whether the actuator is or is not acceptable.