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.