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As air fryers become a staple in modern kitchens, scientists have begun examining how they affect the air inside our homes.
A new study from the University of Birmingham suggests that air fryers can reduce pollution released during cooking, even when the food is very high in fat. Compared with common frying techniques, the researchers found that air frying produces far fewer airborne particles.
The work, published in the American Chemical Society journal ES&T Air, is among the first to identify the full mix of pollutants emitted during air frying. This matters because surveys suggest air fryers have rapidly become an essential appliance in many UK kitchens. Across a range of foods, the team measured lower emissions of volatile organic compounds (VOCs) and ultrafine particles than are typically seen with pan-frying or deep-fat frying.
The study builds on earlier findings from the same research group, which showed that air frying chicken breasts released significantly fewer VOCs. This time, the researchers focused on whether the fat content of food changes what ends up in the air. Both VOCs and ultrafine particles have been linked to health concerns, but indoor sources such as cooking have received far less attention than outdoor pollution.
Measuring emissions from different foods
To monitor cooking emissions in detail, the University of Birmingham team ran experiments inside purpose-built air quality chambers designed to detect small changes in VOCs and other airborne particles. They used a commercially available 4.7-litre air fryer and cooked batches of frozen fried foods, fresh low-fat foods and fresh high-fat foods so that results could be compared under standardised conditions.
Even within the air fryer, certain foods stood out. Frozen onion rings, likely because of their pre-fried oil coating, along with smoked and unsmoked bacon, both of which contain processed fat and whose thin shape causes the fat to fry almost instantly, produced the highest levels of cooking-related emissions in the tests.
But the biggest differences emerged when the same high-fat foods were cooked using a different method. Deep-fat frying produced VOC levels 10 to 100 times higher. The researchers say this is consistent with their earlier work in a research kitchen, where cooking lean chicken breasts in oil using various methods produced similarly elevated pollutant levels compared with air frying.
Health implications and expert insights
Professor Christian Pfrang of the University of Birmingham, the study's lead author, said: "This study is the latest to demonstrate the potential benefits of using air fryers for cooking on indoor air quality. While our previous study looked at only one type of food, lean chicken, we wanted to look at a wider range of foodstuffs, including those with a higher fat content, to see specifically how they compare when cooked in an air fryer."
Ruoyi Tang, first author and a final-year PhD student at the University of Birmingham who carried out the experiments, said: "The results confirmed that although high-fat foods produce more emissions in the air fryer, they still only produce a fraction of what we see with cooking methods such as pan-frying or deep-fat frying. Using a dedicated air quality chamber for this latest study allowed us to take a more detailed look at the emissions produced by air frying as well, helping us focus purely on cooking's contribution to air pollutants."
Prolonged use without deep cleaning causes background emissions
The team also found that air fryers began emitting VOCs and ultrafine particles during an "empty tray test" designed to detect residual emissions.
Tests carried out on an air fryer that had been used more than 70 times revealed 23% higher cooking-related VOC emissions, and more than double the number of ultrafine particles emitted. The team attributes this to residue building up in areas of the air fryer that could not be reached for cleaning.
The cooking-related ultrafine particles measured in these tests, including background emissions from an older appliance, were still far lower than those produced by other cooking methods.
The study also provides a detailed breakdown of the types of VOCs emitted during cooking, which have been linked to health concerns. Ketones, aldehydes and alkenes generated by hot oils and food browning were detected across all the foods cooked, but total VOC levels remained several times lower than the recommended limits set out in UK government building regulations.
Professor Pfrang said: "Our study shows that repeated use of air fryers without the ability to clean hard-to-reach cooking surfaces can undo some of the indoor air quality benefits. While the effects don't produce emissions that should worry families, this finding underlines the need for air fryer designs that allow for deep cleaning to keep emissions low over the long term."
He added: "Air quality in the home and other indoor environments is increasingly being recognised as an important factor, and our body of research will give households a better understanding of how kitchen activities affect the air we breathe in our homes."
Source: SciTechDaily