Development of airborne particulate matter reference materials for chemical measurements and long-term monitoring of environmental changes
Airborne particulate matter (PM) has drawn significant attention due to its detrimental effects on the environment and human health. Exposure to PM is associated with adverse health outcomes, including respiratory and cardiovascular diseases, and has recently been implicated in neurodegenerative diseases. The toxicity of PM is influenced not only by its size but also by the hazardous chemicals it contains. Understanding the composition of these chemicals can provide insights into the origins and growth mechanisms of PM. Given the complexity of PM samples, accurate chemical measurement is challenging, necessitating the development of certified reference materials (CRMs) for method validation and quality control. The Korea Research Institute of Standards and Science (KRISS) has developed urban PM CRMs, collected from intake air filters in the Greater Seoul area, South Korea, to facilitate the precise analysis of chemicals in PM. Here, we outline the analytical approaches used for characterizing elements, polycyclic aromatic hydrocarbons (PAHs), water-soluble ions, total carbon, and isotope ratio deltas of carbon, nitrogen, sulfur, and lead in the CRM, as well as microbiomes. Additionally, it covers the homogeneity and stability assessments conducted. The development of the other PM CRMs, including those from subway stations, on-road environments, and filter-type PM CRMs, along with their characterized measurands, will also be discussed. The PM CRMs developed here are expected to enhance the quality of chemical analysis in PM samples, contributing to reliable assessments of PM-mediated toxicity, source identification, and other fundamental researches, providing essential resources for the ongoing monitoring of environmental changes. Considering the diversity of hazardous substances in various PMs, future analytical challenges related to emerging contaminants including micro/nano-plastics will be also explored.