A respirator leak detection system and method for increasing the sensitivity and accuracy of leak detection through the fit seal of a respirator. A charged particle separator is used to separate charged particles that pass therethrough and to draw charged particles away from an aerosol flow into a clean gas flow. The separator may also be configured as an aerosol concentrator that takes in a major aerosol flow and outputs a minor flow of higher particle concentration. Neutral particles having no charge, which may have passed through the filtering medium respirator and which are not indicative of fit seal leaks are not entrained in the output flow for subsequent detection, thus increasing the accuracy of the filter leak detection system.