Differentiated emissions and secondary organic aerosol formation potential of organic vapor from industrial coatings in China

Organic vapors emitted during solvent use are important precursors of secondary organic aerosols (SOAs). Industrial coatings are a major class of solvents that emit volatile and intermediate volatile organic compounds (VOCs and IVOCs, respectively). However, the emission factors and source profiles of VOCs and IVOCs from industrial coatings remain unclear. In this study, representative solvent- and water-based industrial paints were evaporated, sampled and tested using online and offline instruments. The VOC and IVOC emission factors for solvent-based paints are 129–254 and 25–80 g/kg, while for water-based paint are 13 and 32 g/kg, respectively. In solvent-based paints, the VOCs are mainly aromatics, while the IVOCs are composed of long-chain alkanes, alkenes, carbonyls and halocarbons. The VOCs and IVOCs in water-based paint are mostly oxygenates, such as ethanol, acetone, ethylene glycol, and Texanol. During the evaporation of solvent-based paints, the fraction of IVOCs increases along with those of alkenes and aldehydes, while the proportion of aromatics decreases. For water-based paint, the fraction of IVOCs slightly decreases with evaporation. The SOA formation potentials of solvent-based paints are 8.6–28.0 g/kg, much higher than that of water-based paint (0.65 g/kg); thus, substituting solvent-based paints with water-based paints may significantly decrease SOA formation. Organic vapor emissions from industrial coatings are air toxics, and volatile organic compounds (VOCs) and intermediate volatile organic compounds (IVOCs) are vital components, threatening human health and the environment. However, the VOCs and IVOCs emission characteristics of industrial coatings and their possible contributions to secondary organic aerosol (SOA) are not well understood. This study established an evaporation, sampling and testing system, and characterized VOCs and IVOCs emissions and SOA formation potential of typical industrial paints. The findings are helpful to accurately assess the environmental impacts of industrial paints and highlight the urgency to replace solvent-based paints with water-based paints.