Full-volatility characterization of ROC emissions from industrial coatings reveals a mass-hazard decoupling driven by emerging toxicants.

Industrial volatile chemical products (VCPs), particularly those used in industrial coating applications, have emerged as major sources of reactive organic carbon (ROC) emissions with implications for atmospheric chemistry and human health. However, coating-related ROC emissions remain poorly constrained, limiting assessment of their environmental and health impacts. Here, we characterized full-volatility ROC emissions from representative industrial coating processes across gas and particle phases and estimated China's national ROC emissions from downstream coating processes at approximately 5.31 Tg yr⁻¹ in 2019. Volatile organic compounds (VOCs) dominated the characterized ROC mass in the high-volatility range, with aromatics (35.6%) and cyclic alkanes (20.4%) as major hydrocarbon groups, whereas oxygenated and functionalized organics increased at lower volatility ranges. However, emission mass alone did not reflect health relevance. Species prioritized by quantitative lifetime cancer risk (LCR) and hazard index (HI) assessment represented approximately 22.6% of the characterized ROC mass but dominated the calculated risk indicators. The top two cancer-risk contributors, 1,2-dichloroethane and trichloroethylene, accounted for 96.3% of the summed LCR while representing only 5.07% of the characterized ROC mass. In addition, a recurrently detected emerging-pollutant subset, including polycyclic aromatic hydrocarbons (PAHs), phthalates, phenolic antioxidants, and cyclic siloxanes, represented only ∼0.22% of the characterized ROC mass but was prioritized by complementary toxicity screening. These findings indicate a pronounced mismatch between emission mass and health hazard in coating-related ROC emissions, suggesting that conventional mass-based VOC metrics may underestimate health-relevant risks. A hazard-prioritized, tiered management framework is therefore proposed to support risk-oriented mitigation and more comprehensive full-volatility ROC regulation.