Evaluation of air purifiers' effectiveness for removing radioactive aerosols indoors

Air purifiers with different purification principles and airflow rates were tested under controlled, yet realistic, indoor conditions in an office environment. A stable aerosol atmosphere was generated using a NaCl solution aerosol with a dominant particle size of approximately 100 nm and a total concentration of ∼1.0 × 10⁵ particles·cm^-3, serving as a surrogate for radioactive aerosols. Aerosol size distributions and total particle concentrations were continuously monitored using scanning mobility particle sizers with a time resolution of 3 min. Each experiment was conducted over a 30-min interval to ensure comparability and statistical robustness. Purification efficiency was assessed based on relative and total decreases in aerosol concentration. The tested air purifiers achieved substantial reductions in particle concentrations, with the highest efficiencies observed in devices equipped with HEPA filtration. At the same time, electrostatic systems exhibited slower but measurable reductions over extended operation. Although the study does not directly quantify the reduction in radioactive dose, the results demonstrate that portable air purifiers can effectively remove aerosol particles within size ranges that dominate indoor radioactive aerosol activity. These findings support the role of air purifiers as auxiliary tools for reducing potential inhalation exposure to particle-bound radioactive aerosols in indoor environments.