α−Fe2O3 nanoparticles and hazardous air pollutants release during cooking using cast iron wok in a commercial Chinese restaurant

Long-term exposure to fine particles (PM 2.5 ), ultrafine particles (UFPs), and volatile organic compounds (VOCs) emissions from cooking has been linked to adverse human health effects. Here, we measured the real-time number size distribution of particles emitted when cooking two served food in Chinese restaurants and estimated the emission rate of UFPs and PM 2.5 . Experiments were conducted under a control hood, and both online measurement and offline analysis of PM 2.5 were carried out. The measured emission rates of PM 2.5 generated from deep-frying and grilling were 0.68 ± 0.11 mg/min and 1.58 ± 0.25 mg/min, respectively. Moreover, the UFPs emission rate of deep-frying (4.3 × 10 9 #/min) is three times higher than that of grilling (1.4 × 10 9 #/min). Additionally, the PM 2.5 emission of deep-frying was comprised of a considerable amount of α−Fe 2 O 3 (5.7% of PM 2.5 total mass), which is more toxic than other iron oxide species. A total of six carcinogenic HAPs were detected, among which formaldehyde, acrolein, and acetaldehyde were found to exceed the inhalation reference concentration (RfC) for both cooking methods. These findings can contribute to future evaluation of single particle and HAPs emission from cooking to better support toxicity assessment. • UFPs emission rate from deep-frying shows three times higher than that of charcoal grilling. • The emitted particles from deep-frying contribute higher deposited surface area at alveolar region. • αFe 2 O 3 - a toxic nanoparticle was leaked from cast iron wok-based cooking. • Concentration of four carcinogenic HAPs exceeded the inhalation reference concentration (US EPA).