Droplet surface exposure measurement of a large splashing oil fume in the kitchen with a fluorescent 3D microscopic passive testing method

Abstract Cooking is a major source of indoor particulate matter, surpassing smoking. Large splashing oil fumes produced by water-oil interactions while cooking have received increasing attention for their common and significant hazards. However, the pollution of large splashing droplets is rather difficult to quantitatively measure with the current techniques. In this study, a fluorescent 3D microscopic passive testing method that is accurate and reliable for large spaces and broad-spectrum droplets is developed by combining fluorescence tracer, passive sampling, microscopic vision and droplet 3D reconstruction technologies. The measurement error for submicron droplets is approximately 22.6%. Because large droplet pollution is not unique to the kitchen, our innovative test method is worthy of reference in many fields, such as cleaning and painting workshops. We tested the surface exposure of a large splashing oil fume of 1–500 μm with this method. The results showed that the particle size of splashing oil droplets presents a bimodal distribution, which matches the two generation mechanisms that have been observed. The surface exposure mass concentration of all droplets of 1–500 μm on the surface at a distance of 0.75 m from the emission source edge is reduced to 3.6% of 0.25 m. Droplets (10–100 μm) are the main pollutants, which have continuous indirect hazards and require more attention.