Electrostatic precipitators (ESPs) are an attractive solution for removing airborne particles due to their low pressure drop, low energy consumption, and high filtration efficiency. Their main drawback, however, is ozone production, which has constrained their use in applications where people may be exposed to ozone. The aim of this work was to study the feasibility of using a small ESP for personal protection and as a supply-air filter in residential ventilation systems.

A miniature electrostatic precipitator was designed and constructed to evaluate its performance. The two-stage device consisted of a unipolar needle corona charger and a conventional parallel-plate collector. The objective was to determine whether efficient operation could be achieved with minimal ozone production and low power consumption. Filtration efficiency was measured using diethylhexyl sebacate (DEHS) test aerosol and an optical particle analyzer at an airflow rate of 95 L/min, corresponding to the flow rate used for testing P2/P3-class respirator filters. A target filtration efficiency of >94%, in accordance with the requirements for P2-grade filters, was achieved at a charger voltage of 6 kV and a charging current of 5.5 µA. At these operating conditions, the ozone concentration was 40 µg/m³, which is below the WHO guideline value of 100 µg/m³. Higher voltages further improved removal efficiency but at the cost of increased ozone production and power consumption.

To further reduce ozone concentration, an invention developed and patented by VTT researchers was evaluated. The approach employs collector plates coated with an ozone-reactive material...