Concentrations and solubility of metals from indoor and personal exposure PM2.5 samples

An assessment of trace metal quantification capabilities for indoor (123±53 μg; mean±standard deviation of particle mass) and personal exposure (PE) (32±12 μg) PM2.5 samples from Baltimore, MD was undertaken as part of an EPA study investigating health effects associated with particulate matter. This study included determination of total PM2.5 metal concentrations by energy dispersive X-ray fluorescence and instrumental neutron activation analysis, as well as method development to quantify amounts of water and acid-extractable metals from PM2.5 using inductively coupled plasma-mass spectrometry (ICP-MS). Analytical uncertainties, filter blank contributions, and sample preparation were all found to significantly impact quantification limits. The ICP-MS leaching procedure resulted in partial extraction of metals from the PM2.5. Most of the extractable components of the metals were in a water-soluble form suggesting a high potential for bioavailability of elements from respiratory exposure to PM2.5. A comparison of PM2.5 trace metal concentrations from indoor air samples collected from a central indoor site versus concurrently collected PE samples indicates that resident activities result in exposure to higher concentrations of soluble trace metals.