Pan frying a chicken breast produces 150 times more particulate matter than air frying it, according to new research from the University of Birmingham.
The study, which directly compared cooking methods in a controlled kitchen, establishes the appliance as the cleanest option for indoor air quality.
Using custom air quality chambers for sensitive measurements, the team compared emissions from a commercially available air fryer to traditional methods like shallow and deep-fat frying.
They found that air frying produced far fewer volatile organic compounds (VOCs) and ultra-fine particles than other frying techniques. Even high-fat foods like smoked bacon, which produced the highest emissions in the air fryer, generated 10 to 100 times fewer VOCs when air-fried compared to being cooked in a deep fat fryer.
When cooking a chicken breast using five methods, the peak concentrations of particulate matter micrograms per cubic metre of air were as follows:
- Air frying: 0.6
- Boiling: 0.7
- Deep frying: 7.7
- Stir-frying : 26.7
- Pan frying: 92.9
The pattern was identical for VOCs. Measured in parts per billion (ppb), air frying emitted just 20 ppb, versus 260 ppb for pan frying and 230 ppb for deep frying.
Lead author Professor Christian Pfrang from the School of Geography, Earth and Environmental Sciences, said: ‘Our study shows that air frying produces a tiny fraction of the indoor air pollution emitted by other cooking methods like pan and deep frying.
‘There are a number of factors that will affect the levels of pollution from cooking alongside the method used, including the amount of oil used and the temperature of the stove. What we can say with certainty, however, is that improving the ventilation in kitchens by opening windows or using extractor fans, will help to disperse polluting particles and reduce personal exposure.
‘Particles will remain in the air for quite some time after you have finished cooking, so continuing to ventilate, or keeping extractor fans turned on for a period of time, will really help to avoid the build-up of this indoor pollution.’
However, the research uncovered a significant caveat: poor cleaning habits can lead to background pollution. Tests on an air fryer used more than 70 times without a deep clean revealed it emitted 23% more VOCs and over twice the ultra-fine particles during empty ‘idle’ tests, compared to a clean machine. The team attributed this to a build-up of residues in hard-to-reach components.
Professor Pfrang added, ‘Our study shows that repeated use of air fryers without being able to clean the more inaccessible cooking surfaces can negate some of the benefits for indoor air quality.’
Despite this, even the emissions from a heavily used air fryer remained substantially lower than those from conventional frying. The study also identified the specific VOCs released, such as ketones and aldehydes from heated oils, but noted that total levels were well below UK indoor air quality limits.
The full research can be read here.
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