Frying vs. boiling vs. stir-frying… Which is worst for air quality?

Fine dust and harmful gases generated during cooking degrade indoor air quality and can cause respiratory and cardiovascular diseases. A recently published study found that indoor air pollution levels vary depending on the cooking method. Considering indoor air quality, what is the best cooking method?

A research team of atmospheric sciences at the University of Birmingham in the UK analyzed changes in indoor air quality according to five cooking methods: boiling, frying, stir-frying, grilling, and air-frying in an experimental kitchen.

The research team cooked 120g of chicken breast a total of 90 times using each method: ▲baking 24 times, ▲stir-frying 20 times, ▲frying 16 times, ▲boiling 16 times, and ▲air-frying 14 times. After performing these methods, they measured the level of indoor air pollution using an optical aerosol spectrometer and a proton transfer reaction time-of-flight mass spectrometer. These two measurement methods detect volatile organic compounds (VOCs) and particulate matter (PM), which are representative indoor air pollutants. According to the UK Environment Protection Agency, particulate matter can affect the lungs and heart, increasing the risk of ▲heart attack ▲arrhythmia ▲coughing ▲worsening of asthma, etc. VOCs cause various health problems such as ▲throat irritation ▲headache ▲liver damage ▲heart damage ▲cancer.

The analysis found that air fryers produced the least indoor air pollution compared to the other four cooking methods.

The highest concentration of particulate matter by cooking method was as follows: ▲baking 92.9 ▲stir-frying 26.7 ▲frying 7.7 ▲boiling 0.7 ▲air frying 0.6. The concentration of volatile organic compounds was as follows: ▲baking 260 ppm ▲frying 230 ppb ▲stir-frying 110 ppb ▲boiling 30 ppb ▲air frying 20 ppb.

"Cooking food in an air fryer instead of frying or stir-frying can significantly reduce exposure to indoor pollutants," said Dr. Christian Frang, who led the study. Air fryers use high-speed fans inside the appliance to evenly distribute hot air, crisping food. They use significantly less oil than other cooking methods, resulting in less smoke being released into the air. Because they cook in a sealed container, they effectively prevent hot oil and smoke from escaping onto walls or into the atmosphere.