Evaluation of a high flow rate electrostatic precipitator (ESP) as a particulate matter (PM) collector for toxicity studies

Abstract

In this study, we investigated the performance of an electrostatic precipitator (ESP) operating at high flow rates (i.e., 50–100 lpm) as a fine particulate matter (PM2.5) collector for toxicological studies. The ESP optimum configuration (i.e., flow rate of 75 lpm and applied voltage of +12 kV) was determined based on maximum particle collection efficiencies and minimum ozone emissions associated with the instrument using different laboratory-generated aerosols. This configuration resulted in particle collection efficiencies above 80% for almost all particles in the size range of 0.015–2.5 μm while the ozone concentration was 17 ppb. The ESP was then deployed to our sampling site in central Los Angeles to evaluate its performance using ambient particles under the optimum configuration. Chemical composition and oxidative potential of PM2.5 samples collected on the foils placed inside the ESP tube were compared with those collected concurrently on filters and aerosol slurries using the versatile aerosol concentration enrichment system (VACES) operating in parallel. Our results demonstrated that the ESP was more efficient in preserving labile inorganic ions and total organic carbon (TOC) compared to filters. PM samples collected on ESP substrates also showed higher intrinsic oxidative potential compared to the filters, which might be the result of better preservation of redox active semi-volatile organic compounds on the ESP substrates. However, the TOC concentrations and intrinsic oxidative potential of PM samples collected on ESP substrates were somewhat lower than the aerosol slurries collected by the VACES, probably due to deficiency of water-insoluble compounds in extracted PM samples from ESP substrates. In conclusion, while particle collection for toxicological purposes by the ESP is somewhat inferior to a direct aerosol-into-liquid collection, the ESP performs equally well, if not better, than conventional filter samplers and can be utilized as a simple and adequately efficient PM collector for toxicological studies.