Vertically-resolved indoor measurements of air pollution during Chinese cooking

Chinese cooking features several unique processes, e.g., stir-frying and pan-frying, which represent important sources of household air pollution. However, factors affecting household air pollution and the vertical variations of indoor pollutants during Chinese cooking are less clear. Here, using low-cost sensors with high time resolutions, we measured concentrations of five gas species and particulate matter (PM) in three different sizes at multiple heights in a kitchen during eighteen different Chinese cooking events. We found indoor gas species were elevated by 21%-106% during cooking, compared to the background, and PMs were elevated by 44%-159%. Vertically, the pollutants concentrations were highly variable during cooking periods. Gas species generally showed a monotonic increase with height, while PMs changed more diversely depending on the cooking activity's intensity. Intense cooking, e.g., stir-frying, pan-frying, or cooking on high heat, tended to shoot PMs to the upper layers, while moderate ones left PMs within the breathing zone. Individuals with different heights would be subject to different levels of household air pollution exposure during cooking. The high vertical variability challenges the current indoor standard that presumes a uniform pollution level within the breathing zone and thus has important implications for public health and policy making.