Spatiotemporal Evolution, Secondary Transformation and Control of Cooking Oil Fumes in Open-Plan Kitchens

Cooking oil fumes (COFs) are a major source of spatially heterogeneous indoor air pollution in open-plan kitchens. Proton transfer reaction time-of-flight mass spectrometry (PTR-TOF-MS) was used to monitor COFs, focusing on six typical pollutants: benzene, toluene, butadiene, acrolein, acetaldehyde, and formic acid, measured at six spatially distributed points. Near the stove, thermally driven convection led to vertical stratification: volatile aromatics accumulated in the upper zone, while heavier alcohols and carbonyls settled lower. Partial least-squares-discriminant analysis (PLS-DA) confirmed distinct COF compositions at ceiling level, while lower zones across the kitchen and living area shared similarities due to horizontal advection. All six compounds showed substantial concentration losses during migration, indicating nonuniform exposure risk from kitchen to living room. Formic acid exhibited slow secondary formation, leading to its delayed presence in the living area. Cross-correlation analysis identified toluene and butadiene as likely precursors of formic acid via gas-phase oxidation through secondary transformation (peak lag = -1; r = 0.593 and 0.578). Natural ventilation significantly reduced near-source acrolein by up to 95%, highlighting the role of window opening as an effective mitigation strategy.