No evidence electric charge increases inhaled ultrafine particle deposition in human lungs

<b>Background</b>: Inhalation of aerosol particles from the environmental air, (natural and industrial sources) results in the deposition of potentially hazardous particulate substances in the human respiratory tract. Recent evidence has shown an increase in adult and childhood leukaemia risk near high-voltage power lines (HVPL). This may be explained by ultrafine particles of air pollution becoming electrostatically charged through contact with corona ions emitted by the power lines. <b>Aim</b>: We investigated the hypothesis that particles with excess charge have a higher probability of human lung deposition than 9charge-neutralised9 particles. <b>Methods</b>: We developed and characterized an ultrafine particle generation and delivery system in order to investigate the lung deposition of positively (CP) and neutrally charged (CN) 100nm particles in eight healthy adult subjects. The primary outcome measure was penetration index (PI), a measure of aerosol lung deposition and penetration relative to an inert gas (Krypton). The particle number deposition efficiency (DFp) was also measured. <b>Results:</b> PI and DFp were identical for both charged and uncharged particles (Table). This indicates that the mechanism of electrostatically-enhanced deposition did not have a measurable effect on particle lung deposition in adults and our results are contrary to the corona ion hypothesis. <b>Conclusion:</b> Corona ions from HVPL may not be a key determinant influencing adult and childhood hemato-oncological risk.