## 2 Materials and Methods
### Experimental Design  
This study aimed to determine the effect of using breathable cooling wear and portable airflow cooling devices on PPE for virus handling on user comfort and physiological responses. The conditions of the research room, which were designed to replicate the tropical climate in Indonesia, included a temperature of 30 \(\pm\) 2 \({}^{\circ}\)C and a relative humidity of 50 \(\pm\) 10% [6]. The experimental protocol was designed with light workloads ranging from 40 to 50 W and medium workloads ranging from 50 to 100 W [24]. The experiment was conducted using a cross-sectional approach and within-subject design (repeated measures), with three tests with three different PPE ensembles. The participants were organized according to a randomized crossover design [11] and each participant underwent experiments at intervals of at least one week to mitigate the influence of adaptation and previous training. The experimental protocol included preparation and physical effort (1 h) that represented the activities of health workers at work. The experimental protocol was developed based on the experiments of [PERSON] et al. [25] and [PERSON] et al. [18] and consisted of physical activity with some adjustments, such as the type of activity and the duration of work. Before collecting the data, the participants rested (in the laboratory area), took a second break in the laboratory (20 min), wore complete PPE for 30 min, and then performed six activities for 9 min each, with a rotation time of 1 min (Figure 5). The walking speed on the treadmill was set to a low speed [26; 27]. Parameter measurements were taken during the transitions between activities in the experimental protocol. The experiment was conducted at the Laboratory of Work Systems Engineering and Ergonomics, Faculty of Industrial Technology, Institut Teknologi Bandung, between 9:00 a.m. and 4:00 p.m. The measured impacts consisted of discomfort parameters, as indicated by a categorical scale with seven points for thermal discomfort sensation (3: very comfortable,  
Figure 5: Experimental procedure. 2: comfortable, 1: somewhat comfortable, 0: neutral, \(-1\): slightly uncomfortable, \(-2\): uncomfortable, and \(-3\): very uncomfortable), and seven points for wetness discomfort sensation (3: very dry, 2: dry, 1: somewhat dry, 0: neutral, \(-1\): slightly wet, \(-2\): wet, and \(-3\): very wet) [28; 29]. The physiological parameters included core body temperature (temperature at the ear canal) and skin temperature (at 4 points, i.e., neck, right scapula, left hand, and right calf). Skin temperature (Tsk) was calculated using the following formula: \((Tsk)=0.28~{}T~{}neck+0.28~{}T~{}right~{}sequula+0.16~{}T~{}left~{}hand+0.28~{} trig~{}calf\)). These temperatures were measured using a Beurer FT65 Digital thermometer (Beurer, Ulm, Germany) [30]. Oxygen consumption and heart rate were measured using a VO2 Master Pro type 1.4.0 (VO2 Master, Vernon, BC, Canada). Blood pressure was measured using an Omron digital hem 8712 brand sphygmomanometer (Omron Corporation, Kyoto, Japan). Sweat intensity was determined based on body mass loss which was measured before and after the experiment using an Omron brand scale, Karada Scan Body Composition Monitor HBF-375 (Omron, Kyoto, Japan), and sweat on clothing was measured using a Henherr Electronic Balance BL H2 (Henherr, Taiwan). The temperature and humidity of the microclimate room were measured on the right chest using a thermohygrometer, specifically the SATO model SK-L200 TH (Sato Keiryoki Mfg. Co., Ltd., Tokyo, Japan). The instruments used for measurement are described in Table 3.