The present invention relates to a Wet Electrostatic Precipitator Air (WEPA) Purifier and purification method capable of stand-alone operation as the principal air purification system, particularly in military applications. This system is intended to supply small military units within a temporary structure clean, threat-free fresh air for periods up to 12 months without maintenance. The WEPA Purifier is configured to remove and sterilize biological threat particles from an airflow, and further remove and sequester radioactive particulates, thus allowing them to be safely removed at normal maintenance periods. The WEPA Purifier includes a wet electrostatic precipitator filtration element in which particles are charged and collected by a capturing solution flowing over an attracting electrode collection plate. The water is returned by gravity to a reservoir where it is disinfected and captured particles retained in a small, low maintenance, regenerative liquid filter.