Quantification of Volatile Organic Compounds (VOCs), Nitrogen Oxides (NO_x), and Ultrafine Particles (UFPs) Emitted by Domestic Air Fryers: A Chamber Study of Indoor Air Quality Impacts

Air frying has emerged as a popular low-oil cooking method, yet its impact on indoor air pollutant emissions remains insufficiently understood. In our study, emissions of volatile organic compounds (VOCs), nitrogen oxides (NO_x), and ultrafine particles (UFPs) were measured during the air frying of 12 different dishes within a ca. 0.15 m³ Perspex chamber. Pollutant emissions varied significantly depending on the food type, with rates in the ranges of 17.8-184.0 μg min^-1 for total cooking VOCs, 24.6-37.9 μg min^-1 for NO_x, and 0.1-17.4 × 10¹² # min^-1 for UFPs, primarily due to Maillard reactions and lipid thermal decomposition. While pollutant concentrations and ozone formation potentials were elevated within the chamber, scaling to the volume of a small kitchen indicated substantially lower levels compared to conventional frying methods. Notably, only high-fat foods produced UFP concentrations comparable to those of deep frying. No NO_x emissions were found during blank (empty appliance) runs, and NO_x was only detectable while cooking certain types of foods. However, residues accumulating within inaccessible areas of the air fryer following over 70 uses led to increases of 23% in VOC and 236% in UFP concentrations while not cooking food.