Performance of electrostatic dust collectors (EDCs) for endotoxin assessment in homes: Effect of mailing, placement, heating, and electrostatic charge

ABSTRACT

Electrostatic Dust Collectors (EDCs) are in use for passive sampling of bioaerosols, but particular aspects of their performance have not yet been evaluated. This study investigated the effect of mailing EDCs on endotoxin loading and the effect of EDC deployment in front of, and away from, heated ventilation on endotoxin sampling. Endotoxin sampling efficiency of heated and unheated EDC cloths was also evaluated. Cross-country express mailing of dust-spiked EDCs yielded no significant changes in endotoxin concentrations compared to dust-only samples for both high-spiked EDCs (p = 0.30) and low-spiked EDCs (p = 0.36). EDCs were also deployed in 20 identical apartments with one EDC placed in front of the univent heater in each apartment and contemporaneous EDC placed on the built-in bookshelf in each apartment. The endotoxin concentrations were significantly different (p = 0.049) indicating that the placement of EDC does impact endotoxin sampling. Heated and unheated EDCs were deployed for 7 days in pairs in farm homes. There was a significant difference between endotoxin concentrations (p = 0.027) indicating that heating EDCs may diminish their electrostatic capabilities and impact endotoxin sampling. The last study investigated the electrostatic charge of 12 heated and 12 unheated EDC cloths. There was a significant difference in charge (p = 0.009) which suggests that heating EDC cloths may make them less effective for sampling. In conclusion, EDCs can be mailed to and from deployment sites, EDC placement in relationship to ventilation is crucial, and heating EDCs reduces their electrostatic charge which may diminish their endotoxin sampling capabilities.

KEYWORDS:

• Endotoxin
• exposure assessment
• house dust
• passive sampling

Acknowledgments

The authors thank the occupants of the studied farm homes and the apartments for their cooperation and hospitality. Nick Verna provided assistance by express mailing the EDCs back to the University of Iowa from North Carolina. The authors would like to acknowledge use of the University of Iowa Central Microscopy Research Facility. The authors would also like to thank the University of Iowa Physics Department for providing the apparatus for electrostatic charge measurements and Sarah S. Perry for reviewing the statistical analyses.

Funding

This work was supported by the University of Iowa, Environmental Health Sciences Research Center [NIH P30 ES005605]. The Hitachi S-4800 SEM was acquired by the University of Iowa Central Microscopy Research Facility through an NIH Shared Instrumentation Grant [1 S10 RR022498-01].