Electrostatic precipitation is a well-known technology to reduce public exposure to radon daughters. A custom electrostatic precipitator (ESP) prototype has been designed and built to study the effectiveness of such a removal technique in specific workplaces having low-to-zero air exchange rates with external environments. An appropriate mathematical model has been set up in order to simulate the behavior of environmental and nuclear data throughout the ESP operation, to optimize the design for the prototype to be built, to estimate its effectiveness in terms of effective dose reduction. Reference detectors have been used to measure both the radon concentration and the potential alpha energy concentration of its decay products. After a full calibration procedure, two main experiments have been performed in a room satisfying the requirements of very low ventilation rate and high radon concentration. The effective dose rate after an ESP continuous working period of either 3 h or 5 h turned out to be 50% lower than the value measured before ESP switching ON. The main contribution to dose reduction was found to be given by the first 2 hours of operation.