Indoor air quality has become an urgent concern in recent times, as we spend a considerable amount of time inside our home. Advances in measurement technologies have revealed that small, otherwise invisible ultrafine particles (UFPs) pose a significant threat to indoor air quality. While there are outdoor sources of this particulate air pollutants, the most common source lies indoor. The UFPs emitted by small home appliances equipped with electric heating coils and brushed DC motors can reach to the users as they are deployed close to the users without any preventive shield.
In a new study published from Pusan National University (PNU), a group of researchers led by Professor Changhyuk Kim (Ph.D.), characterize the UFPs emitted by some small electric home appliances using heating coils and brushed DC motors and assess the health hazards of the inhaled UFPs. "Understanding the source of the pollutants help to develop preventive measures and policies for keeping healthy indoor air quality," mentioned Dr. Kim, while talking about the motivation behind the study. This paper was made available online on September 11, 2025 and was published in Volume 498 of the Journal of Hazardous Materials on October 15, 2025.
The assessment was done for three different types of small electric home appliances– hairdryers, air fryers, and toasters. Hairdryers with brushless motors were compared for the study to identify the UFP emission from the brushed motors in the gadgets. The amounts of UFPs emitted by each device were measured, and the chemical compositions and morphologies of heavy metals within the particles were analyzed. The team also used a simulation model to understand how the ultrafine particles affect our respiratory tracts that are most susceptible.
The study showed that most of these appliances emit large quantities of UFPs and the amount of emission often varied based on the operating temperatures. Devices equipped with brushed DC motors and heating coils released up to 10–100 times higher total particle number concentrations compared to brushless types. The heating coils in small electric home appliances frequently contained heavy metals such as copper, iron, aluminum, silver, and titanium. "These associated heavy metals increase the risk of cytotoxicity and inflammation when the particles enter the human body," mentioned Dr. Kim.
The simulation model-based study showed that the UFPs are deposited predominantly in the alveolar region of the lungs. Because children have smaller airway diameters, higher deposition fractions, and greater deposition volume per body weight, they face a higher health risk than adults.
This research can help to reshape how we select home appliances for better indoor air quality, safety and product performance. The findings from this study can be applied to improve the design and regulation of small electric home appliances. Manufacturers can adopt brushless motors and optimized heating components to minimize UFP emissions from the products. Policies and guidelines regarding the manufacture of these gadgets can be made based on the findings of this study.
"Our study emphasizes the need for emission-aware electric appliance design and age-specific indoor air quality guidelines. In the long term, reducing UFP emissions from everyday devices will contribute to healthier indoor environments and lower chronic exposure risks, particularly for young children, than current status. Moreover, this framework can be extended to other consumer products, guiding future innovations toward human health protection," concluded Dr. Kim.
