### Challenges in Wearable Technology for Firefighters  
To date, despite the well-known cardiac risk faced by on-duty firefighters, especially during emergency activities, and its societal importance, there are no available ECG field data recordings during firefighting activities. This is due to external constraints imposed by environmental conditions and/or the effect of personal protective equipment, such as the temperature, radiation, and moisture. Radiation can cause sensor errors, while moisture can decrease the sensor lifespan and restrict long-term monitoring. ECG sensors face significant challenges due to the influence of noise from both the surrounding environment and the human body (e.g., interference from physical movement and breathing), complicating accurate analysis, especially in dynamic conditions. Previous studies have been conducted to explore the integration of ECG-enabled smart textiles into firefighters' gear [3]. A representative effort was the Vital Responder project, which aimed to optimize firefighting efforts and minimize fire damage by developing the VitalJacket, a discreet device capable of monitoring firefighters' cardiovascular status through a one-lead clinical ECG without restricting movement [4]. However, adapting wearable technologies to challenging environments like forest fires presents challenges, resulting in poor-quality ECG signal acquisition due to damaged electrodes, hardware issues, and incorrect time annotations of the data. Another challenge is complying with international safety regulations for textiles in high-heat conditions, as seen in this study. For example, an initial version of the VitalJacket contained over 20% elastane, which ensures good electrode compression against the skin but is heat-sensitive and could potentially cause burns. This is why garments composed of 2% elastane or more are not allowed by European regulations for use in fire contexts due to the associated risk of harming the wearer's skin [5]. Modern firefighting clothes are made from high-tech fire-resistant or thermal-resistant fibers, offering durability and excellent mechanical and abrasive characteristics. Aramid, a popular material in fire-protective clothes and military uniforms, is known for its heat resistance, mobility retention, and lightweight, breathable, and thermally insulating properties ([[https://www.tchaintech.com/CDETAIL/case-firefighter-aramid-fabric](https://www.tchaintech.com/CDETAIL/case-firefighter-aramid-fabric)]([https://www.tchaintech.com/CDETAIL/case-firefighter-aramid-fabric](https://www.tchaintech.com/CDETAIL/case-firefighter-aramid-fabric)) (accessed on 20 November 2024)). A smart undergarment for firefighters is highly valuable for its ability to integrate sensors directly into the fabric to monitor vital signs, stress levels, and physical activity. The integration of sensors into the undergarment also allows for the measurement of physiological signals directly on the firefighter's body, providing precise real-time information to monitor health and safety during firefighting operations [6]. However, a t-shirt undergarment is not suitable for efficient ECG collection during firefighting tasks due to its flexibility and lightness. Additionally, the use of dry electrodes, rather than hydrogel ones, to prevent skin irritation introduces more noise into the ECG signal. Consequently, the increased difficulty in achieving electrode adherence to the skin exacerbates the issue of electrode contact loss [3; 5]. A sports vest could provide a tight fit without conditioning firefighters. The EquiVital project ([[https://equivital.com](https://equivital.com)]([https://equivital.com](https://equivital.com)) (accessed on 20 November 2024)) offers a similar idea but has drawbacks like lycra electrodes oxidating over time. Another challenge in implementing a smart undergarment is the movement of the skin across the electrodes, which introduces noise into the ECG signal [2], and electrode folding and stretching due to firefighters' movements.