Analytical Methods for Physicochemical Characterization and Toxicity Assessment of Atmospheric Particulate Matter: A Review

Abstract

Particle-bound pollutants are a critical risk factor for human respiratory/cardiovascular conditions. A comprehensive analysis of the physicochemical characteristics of PM is often challenging since it requires combining different practical methods with a good understanding the of characterization outputs. The present review aims to (1) provide a comprehensive assessment of the underlying mechanisms of PM cytotoxicity and the related biological response; (2) evaluate the selected methods for PM characterization in terms of outputs, technical aspects, challenges, and sample preparation; (3) present effective means of studying PM physicochemical toxicity and composition; and (4) provide recommendations for enhancing the human health risk assessment. The cellular response to potentially toxic elements in PM is complex to understand as exposure includes systemic inflammation, increased ROS accumulation, and oxidative stress. A comprehensive toxicity assessment requires blending morphological features and chemical composition data. For the morphological/chemical characterization, we recommend first using SEM-EDS as a practical method for the single-particle analysis. Then, the bulk chemistry of PM can be further studied using either a dry analysis (e.g., XRF) or wet analysis techniques (e.g., ICP and IC). Finally, when used on a need basis, the reviewed complementary laboratory methods may further add valuable information to the characterization. The accuracy of the human health risk assessment may be improved using bioaccessible/soluble fractions of the contaminants instead of the total contaminant concentration. Having an integrated understanding of the covered analytical methods along with the health risk assessment guidelines would contribute to research on atmospheric chemistry, molecular biology, and public health while helping researchers better characterize human exposure to PM and the associated adverse health effects.

The Burden of Air Pollution: A Perspective on Global Health Inequalities

“…In practice, measuring the relevant parameters and quantifying their health effects is a difficult task, as many additional external factors strongly influence human morbidity and mortality [49]. Identifying and correcting for the influence of confounding factors remains a challenging task, although scientific advances are continually providing new information on the toxicity of trace elements in ambient PM [50,51]. It is expected that in the future, multi-element analysis will be required for PM determination, allowing the use of models to identify and partition sources [52,53].…”

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“…But the high cost of ICP systems limits their use and atomic adsorption spectroscopy may be suggested. 148…”

“…The most widely employed type of XRF is an energy‐dispersive (ED)‐XRF, followed by (wavelength dispersive) WD‐XRF and Synchrotron radiation induced (SR)‐XRF. SR‐XRF is evidently more sensitive than other traditional XRF techniques enabling a trace elemental analysis 148 …”

“…XPS analysis is conducted under a high vacuum condition therefore the presence of volatile organic compound will be evaporated. Though XPS has some disadvantages such as, it involves the sophisticated spectral deconvolution, charge compensation, and access to databases containing reference spectra of analyzed elements 148 …”

“…Whereas ICP‐OES is more robust and is used for the analysis of soil, solid waste, groundwater, and wastewater. But the high cost of ICP systems limits their use and atomic adsorption spectroscopy may be suggested 148 …”