A-Fe <sub>2</sub>O <sub>3</sub> Nanoparticles Release During Cooking Using Cast Iron Wok in a Commercial Restaurant

Fine particulate matter (PM2.5: aerodynamic diameter of particle less than 2.5 µm) emission from cooking has been widely associated with indoor air quality (IAQ) and human health effects. However, specific physicochemical characteristics of a single PM2.5 regarding its potential toxicity have rarely been reported. This study reports measurements of PM2.5 emission from deep frying with a cast wok and charcoal grilling, along with emission characteristics of hematite (α-Fe2O3) nanoparticle and hazardous air pollutants (HAPs). Deep-frying with a cast iron wok shows six-fold higher PM2.5 emission rate (3.3 × 1011 particles s-1) than charcoal grilling. The PM2.5 of deep frying comprised a considerable amount of α-Fe2O3 (5.7% of PM2.5 total mass), a toxic nanoparticle that triggers higher toxicity than other iron oxide species. A total of 6 carcinogenic HAPs were detected, among which formaldehyde, acrolein, and acetaldehyde were found to be exceed the inhalation reference concentration (RfC) for both cooking methods. These findings can contribute to future evaluation of single PM2.5 and HAPs emission from cooking to better support in terms of toxicity assessment.