Testing the metals hypothesis in Spokane, Washington.

Abstract

A 7-year, time-series, epidemiologic study is ongoing in Spokane, Washington, to examine the associations between ambient particulate constituents or sources and health outcomes such as emergency department (ED) visits for asthma or respiratory problems. One of the hypotheses being tested is that particulate toxic metals are associated with these health outcomes. Spokane is a desirable city in which to conduct this study because of its relatively high concentrations of particulate matter, low concentrations of potentially confounding air pollutants, variability of particulate sources, and presence of several potential particulate metals sources. Daily fine-and coarse-fraction particulate samples are analyzed for metals via energy-dispersive X-ray fluorescence (EDXRF) and instrumental neutron activation analysis. Particulate sources are determined using receptor modeling, including chemical mass balancing and positive matrix factorization coupled with partial source contribution function analysis. Principal component analysis has also been used to examine the influence of sources on the daily variability of the chemical composition of particulate samples. Based upon initial analyses using the EDXRF elemental analyses, statistically significant associations were observed between ED visits for asthma and increased combustion products, air stagnation, and fine particulate Zn. Although there is a significant soil particulate component, increased crustal particulate levels were not found to be associated with ED visits for asthma. Further research will clarify whether there is an association between specific health outcomes and either coarse or fine particulate metal species. Spokane is a semiarid, western city with a medium-sized urban population of approximately 200,000, and over 400,000 who live in the Spokane Valley. The area experiences periodic violations of the air quality standards for particulate matter with a mass median aerodynamic diameter less than 10 µm (PM 10 ) and is currently classified as a nonattainment area for PM 10 . There are several particulate "seasons" that lead to greatly differing particulate chemical characteristics and concentrations (10). In the winter, the Spokane Valley is prone to inversions, and in addition to vehicular exhaust, residential wood burning contributes significantly to particulate pollution. In the fall, prescribed agricultural burning of myriad acres of bluegrass seed and wheat stubble fields takes place. In the late summer, during hot, dry periods, Spokane experiences high PM 10 because of re-entrainment of dust from unpaved roads and parking lots, and during windy periods, windblown dust storms may occur (11). In contrast to many urban areas in the Eastern United States, the sulfur dioxide (SO 2 ) concentration, the fraction of secondary PM mass (including both sulfates and nitrates), and the level of particulate acidity are relatively low in Spokane PM (12). Major point sources of particulate pollution include a municipal waste incinerator and an aluminum smelter and...

Fine Particulate Matter Source Apportionment for the Chemical Speciation Trends Network Site at Birmingham, Alabama, Using Positive Matrix Factorization

“…This problem has been recently addressed with mixed success in numerous applications to study urban air quality and human exposure issues. 13,22,45,[53][54][55][56][57][58][59][60] Three fundamental assumptions underlie all the receptor models: (1) PM compounds are present in different proportions in different source emissions; (2) these proportions remain relatively constant for each source type over the evaluated measurement period; and (3) changes in these proportions between source and receptor, i.e., the chemical transformation during atmospheric transport and dispersion of emissions, are negligible or can be approximated. Here, we employed EPA version 1.1 of the PMF receptor model, solving the multilinear regressions using constrained, weighted, least-squares.…”

PM source apportionment and health effects: 1. Intercomparison of source apportionment results

“…Initially, a program called PMF2 utilizes a unique algorithm (Paatero, 1997) for solving the factor analytic task. PMF2 has been used in a number of recent factor analytic studies (Anttila et al, 1995;Huang et al, 1999;Polissar et al, 1996Polissar et al, , 1998Polissar et al, , 1999Polissar et al, , 2001Prendes et al, 1999;Xie et al, 1999a;Lee et al, 1999Lee et al, , 2002Lee et al, , 2003Paterson et al, 1999;Chueinta et al, 2000;Ramadan et al, 2000;Anderson et al, 2001Anderson et al, , 2002Claiborn et al, 2002;Miller et al, 2002;Qin et al, 2002;Begum et al, 2004;Buzcu et al, 2003;Gao et al, 2003;Kim et al, 2003aKim et al, , b, 2004Larsen and Baker, 2003;Maykut et al, 2003;Qin and Oduyemi, 2003;Hien et al, 2004;Kim and Hopke, 2004a Subsequently, an alternative approach that provides a flexible modeling system, the multilinear engine (ME), has been developed for solving the various PMF factor analysis least-squares problems (Paatero, 1999). ME has already been applied to a number of environmental problems (Xie et al, 1999b;Paatero and Hopke, 2002;Hopke et al, 2003;Kim et al, 2003c;Paatero et al, 2003;Ramadan et al, 2003;Chueinta et al, 2004).…”

p38 and EGF receptor kinase-mediated activation of the phosphatidylinositol 3-kinase/Akt pathway is required for Zn2+-induced cyclooxygenase-2 expression

“…On the other hand, zinc is also a common airborne metallic contaminant that derives from combustion, tire wear, and industrial processes that may contribute to the adverse health effects of ambient pollution (1,2,9,10,17 (31,(51)(52)(53)(54)(55), the regulation of COX-2 expression by these activities in Zn 2ϩ -treated cells has not been characterized. This study characterizes the association of these intracellular signaling pathways with Zn 2ϩ -induced COX-2 expression in human bronchial epithelial cells and their cross talk during this event.…”