## 1 Introduction  
Diseases caused by acute viral infections can cause severe epidemics or pandemics that affect millions of people over time. Past outbreaks include the H\({}_{1}\)N\({}_{1}\) virus (Spanish flu) in 1918, the H\({}_{2}\)N\({}_{2}\) influenza virus in 1957, the H\({}_{3}\)N\({}_{2}\) influenza virus in 1968, the Hantaviruses, the swine flu (H\({}_{1}\)N\({}_{1}\)) in 1997, The Ebola virus in 1976 and 1995-1996, the Nipah virus in 1998, and COVID-19 in 2020 [1]. Anticipation steps need to be prepared, considering the possibility of a similar occurrence in the future [2]. Health workers must wear personal protective equipment (PPE) to reduce the risk of contacting or transmitting diseases caused by highly contagious viruses, such as COVID-19 [3, 4]. The PPE ensemble must provide encapsulation to isolate health workers from patients, ensuring that it has about twice the evaporation resistance compared to standard medical scrubs [3]. PPE materials are made of materials that do not absorb water, are not water permeable, and are not air permeable, so they cannot transfer heat and sweat from the body to the environment ([PERSON] et al., taken from [5]). Tropical climates are characterized by environmental conditions with warm to hot temperatures throughout the year and high air humidity [6]. Work activities using PPE in a hot and humid environment will significantly increase body heat [7], which harms health and reduces worker productivity [3]. Working in a hot and humid work environment also has the potential to decrease efficiency, increase accidents [8, 9, 10, 11], and cause usersto become irritable, restless, and have difficulty concentrating [7; 8]. The body's reaction to reduce heat by increasing blood circulation on the surface of the human body causes reduced blood supply to the brain, resulting in decreased concentration [12]. The use of PPE in hot environments causes side effects in the form of thermal discomfort and the emergence of excessive physiological responses [13]. Symptoms of discomfort include increased body temperature, profuse sweating, sweat-soaked clothing, difficulty breathing, anxiety, headache, weakness, fatigue, disruption of movement, and difficulty changing clothes [8; 14; 15]. The cause of discomfort can be attributed to activities while using PPE in a work environment with a temperature of 30 \({}^{\circ}\)C, resulting in a microclimate temperature close to 34 \({}^{\circ}\)C and with relative humidity reaching 100% [13]. Several studies have attempted to improve the thermal discomfort experienced by individuals wearing PPE ensembles for COVID-19 treatment. Research by [PERSON] et al. [16] conducted in several major cities in China shows that efforts are needed to reduce the occurrence of heatstroke when wearing impermeable PPE. Recommendations include shifting schedules every 2 h for indoor workers, limiting outdoor workers' PPE usage to less than 2 h, advising workers who work for 8 h to use a personal cooling system with a cooling power \(\geq\) 194.8 W/m\({}^{2}\), or ensuring that workers in the testing booth have access to air conditioners set to 25.0 \({}^{\circ}\)C, with a RH of 50-65% and a wind speed of 2.5 m/s. Although this research is very interesting, some adjustments are needed because the climate in China is sub-tropical, whereas the climate in Indonesia is tropical. The high air humidity in the microclimate between the body and clothing has been addressed using a superabsorbent composite layer on the PPE fabric [17]. The superabsorbent composite layer successfully reduces microclimate humidity; however, it causes the PPE fabric to become thick, which inhibits heat transfer to the environment. Cooling wear, in the form of phase change material (PCM) cooled vests, has been used to reduce the risk of thermal strain [18; 19; 20]. However, in both research studies, the thick material is a barrier to transferring heat and sweat vapor from the body to the environment.