Characteristics of PM_2.5 emitted from different cooking activities in China

PM_2.5 samples were collected from five different cooking activities, namely, meat roasting, cafeteria frying, fish roasting, snack-street boiling, and cafeteria boiling in Ya'an, China. Their chemical compositions were investigated. The PM_2.5 concentrations in the cooking samples were 2.5-9.6 times higher than those in the corresponding backgrounds. Meat roasting produced the highest amount of PM_2.5. In general, charbroilings emitted more PM_2.5 than the other cooking activities because of the characteristics of cooking method and fuel type. High organic carbon (OC) contents (>53% of PM_2.5) and OC/EC ratios (>54) in meat roasting and cafeteria frying samples suggest that oils and high-fat raw materials significantly affect the PM_2.5 and OC emissions. However, the cooking activity was proved to be a minor source for elemental carbon (EC) with its low contents in all of the samples. High ion compositions in PM_2.5 and WSOC/OC ratios in the snack-street boiling and cafeteria boiling samples represent that water-based cooking emitted more water-soluble species. Considering that high OC/EC ratios were measured in the oil-based cooking samples and most secondary organic aerosols (SOAs) are water soluble, it is more reasonable to estimate SOA with WSOC/OC ratio in populated urban areas. We found that the formation of SOA is significant when the WSOC/OC ratio is larger than 0.40. Principal component analysis (PCA) with the quantified metals identified four contributors to the samples, including coal combustion and non-licensed business activities, soil dust, charcoal burning, and stainless steel utensils, and explained 73% of the total variance. The high emissions of PM_2.5 and toxic components from the cooking activities suggest that food safety control and environmental standard establishment should be strengthened in small and medium-sized cities in China.