Urban Outdoor?Indoor PM_2.5 Concentrations and Personal Exposure in the Deep South. Part II. Inorganic Chemistry

Abstract

This paper reports the results of an exploratory inorganic chemical characterization of PM_{2 . 5}. The particle samples exemplify the personal exposure of nine healthy, nonsmoking individuals living and working in the metropolitan area of Birmingham, Alabama, in comparison with stationary outdoor and indoor sampling at their homes. The samples were taken by filtration in two seasons, summer and winter of 1997?1998. The chemical analyses were performed on water soluble extracts for sulfate, nitrate, ammonium, chloride, and potassium and x-ray fluorescence spectroscopy for elements of atomic number > 13. The results indicate that a sulfate mixture, calculated to be either ammonium sulfate or letovicite, dominated the mass concentration of all samples. Small contributions also derived from nitrate as ammonium nitrate, chloride, aluminum silicates, and metals such as iron, copper, and zinc. Potentially toxic elements such as chromium, nickel, arsenic, and selenium were present only at the ng/m3 level or less. Most of the unaccounted for mass fraction is hypothesized to be carbonaceous material. Correlation was found between sulfate concentration data from outdoor, indoor, and personal samples. Sulfate concentrations also correlated with outdoor PM_{2 . 5} gravimetric mass concentrations. However, minor or trace contaminant concentrations were not correlated with outdoor mass concentrations. Indoor sulfate levels can be explained by infiltration of outdoor particles into the buildings, while evidence was found for sources of PM_{2 . 5} particles indoors in four of eight residences in summer and two of eight in winter.