Chemical and stable isotopic characteristics of PM_2.5 emitted from Chinese cooking

This study investigated the characteristics of air pollutants generated from preparing Chinese cuisine and analyzed the isotopic compositions of carbon and nitrogen in particulate matter with a diameter <2.5 μm (PM_2.5) to source apportionment study. The CO and CO₂ concentrations and temperatures were measured using suitable instruments in real time during cooking, including stir-fry, fry, deep-fry, hot-pot, and mixed cooking, and periods with non-cooking. Personal environmental monitoring instruments were used to collect PM_2.5 for carbon and nitrogen elements and isotopes analysis. Our data indicated that the concentrations of CO and CO₂ and the temperature were higher during periods of cooking, especially for the fry and stir-fry methods, than during periods with non-cooking. The concentrations of PM_2.5, total carbon, and total nitrogen were also higher during cooking; the maximum concentrations were measured during fry. The values of δ¹³C were considerably lower during the periods of cooking (mean: -28.15‰) than during non-cooking (-27.18‰). The average values of δ¹⁵N were 8.63‰ and 11.74‰ during deep-fry and hot-pot cooking, respectively. The δ¹³C values can be used to distinguish between cooking and other non-cooking sources and further assess the effect of different cooking activities on PM_2.5. The δ¹⁵N only can be used to investigate the effect of deep-fry on PM_2.5. Moreover, the δ¹³C signature suggested that fry emits higher products of incomplete combustion than do other cooking activities. These findings can assist in pollution source identification of PM_2.5, emission control, and the study of combustion characteristics.