# Multi-Sensor Photoelectric Fire Alarm Device Implementation for Early Fire Detection in Campsites
## 1 Introduction  
The devastating consequences of fires, including loss of life and property, inflict significant economic burdens worldwide, with annual damages reaching approximately 1% of the global gross domestic product (GDP) and claiming thousands of lives [1]. As leisure activities such as camping and glamping gain popularity, a worrying trend has emerged: a rise in fire incidents at camping sites. Data from the National Fire Data System corroborates this observation, revealing a 73% surge in camping participation from 3.01 million in 2017 to approximately 5.23 million in 2021. This increase in camping activities was correlated with a notable increase in fire incidents at campsites, from 43 to 71 over a three-year period in South Korea, as shown in Figure 1[2]. Figure 1: Recent three-year fire incident statistics in campsites. The risk of fire outbreaks is particularly high in small and confined environments, such as camping sites. The predominant use of highly flammable materials, such as nylon and polyester, in tent construction exacerbates the rapid spread of fire, making extinguishment and evacuation more challenging, as shown in Figure 2. A fire that spreads radially and involves flaming typically follows a growth pattern proportional to the square of time and is referred to as a t-squared (t2) fire. These fires are categorized by their growth speed--ultra-fast, fast, medium, and slow--based on the time required for the fire to reach a heat release rate (HRR) of 1000 kW (1 MW). [PERSON] [3] reported that fires in a nylon tent classified as a t2 fire growth pattern spread extremely quickly, with the HRR potentially reaching 1 MW in just 20-42 s. This underscores the importance of even marginal reductions in fire detection time, which can provide vital moments for evacuation before flashover--the point at which a fire becomes uncontrollable. In the fire captured in Figure 2, the incident started at approximately 2:10:02, and the tent was fully engulfed by 2:14. Applying these observations to this study, a fire alarm system capable of detecting a fire within 2 min and 48 s could enable timely evacuation, preventing severe injuries by alerting occupants before the flames reach the tent entrance. The proposed fire alarm system significantly enhances early fire detection, thereby reducing the risk of damage and injury. This is particularly vital in camping environments where tents can be completely consumed by fire within 5 min of ignition. The critical \"golden time\" for survival in such fires is the period before flashover, which typically occurs within approximately 5 min. Therefore, early detection is imperative to ensure survival and minimize injury. Furthermore, incidents involving casualties due to toxic gas inhalation in confined spaces, such as tents, have been documented. For instance, in March 2015, a tragic incident at a glamping site on Ganghwa Island, South Korea, resulted in five fatalities [4]. More recently, on 11 November 2023, five campers in South Korea tragically died from carbon monoxide poisoning caused by a brazier inside their tent [5]. Fire-related accidents at campsites are not exclusive to South Korea [6]. This underscores the urgent need for the development and deployment of effective fire detection and alarm systems tailored for camping environments. Figure 2: CCTV footage of campsite fires [7]. Fire detection systems are crucial for providing early warning systems and implementing prevention strategies by identifying critical indicators of fire, such as smoke, flames, and abnormal temperature increases. In a 2022 study, [PERSON] [8] highlighted various sensors used in contemporary fire alarm systems, including heat, gas, flame, multi-composite, graphene oxide (GO) [9], and smoke sensors, as depicted in Figure 3.  
Furthermore, [PERSON] [10] demonstrated a significant correlation between the likelihood of fire occurrence and humidity and temperature.