Molecular-level oxidation mechanisms and secondary pollution impact of volatile chemical products (VCPs)

Volatile organic compounds (VOCs) play a central role in atmospheric oxidation chemistry and the formation of secondary air pollution. Through complex oxidation processes, VOCs generate secondary products with reduced volatility and enhanced toxicity, contributing to secondary organic aerosol (SOA) formation and chemical health risks. In recent years, increasingly stringent regulations on fossil fuel combustion from transportation and industry have substantially altered the composition of anthropogenic VOC emissions in urban atmospheres across the European Union. As traditional sources decline, volatile chemical products (VCPs)—including personal care products, coatings, rubber materials, adhesives, and pesticides—have emerged as a dominant and rapidly growing source of urban VOC emissions.
Despite their importance, VCPs have long been underrepresented in emission inventories, leading to significant uncertainties in current air quality models and an incomplete understanding of their atmospheric oxidation chemistry. In particular, the oxidation mechanisms and kinetics of high-emission VCP species remain poorly constrained, limiting robust assessment of their contributions to secondary pollution and chemical risk.
In recent studies, we investigate the molecular-level oxidation chemistry and environmental impacts of representative high-emission VCPs relevant to urban environments, such as (A) volatile methyl siloxanes (Fu, Z., et al., Environ. Sci. Technol., 2020, 54, 7136-7145), (B) organophosphate esters (Fu, Z., et al., Environ. Sci. Technol., 2022, 56, 6944-6955), (C) linalool (Fu, Z., et al., Environ. Health, 2024, 2, 486-498), and (D) limonene (Fu, Z., et al., Environ. Sci. Technol., 2024, 58, 19762-19773). Focusing on compounds from personal care, coating, and rubber-related products, we combine quantum chemical calculations, detailed kinetic and chemical mechanism modeling, and environmental chamber experiments. This integrated approach aims to (1) elucidate previously unexplored autoxidation and radical-driven reaction pathways, (2) quantify the formation potential of SOA precursors, and (3) assess the yields of toxic secondary oxidation products.
The results will improve mechanistic understanding of VCP atmospheric oxidation, reduce uncertainties in SOA and toxicity predictions, and support the refinement of chemical transport models. Ultimately, these works contribute to improved air quality assessment and chemical risk evaluation, aligning with EU priorities on clean air, chemical safety, and sustainable innovation.