Prediction of Individual Dynamic Thermal Sensation in Subway Commute Using Smart Face Mask.

Wearable sensors and machine learning algorithms are widely used for predicting an individual's thermal sensation. However, most of the studies are limited to controlled laboratory experiments with inconvenient wearable sensors without considering the dynamic behavior of ambient conditions. In this study, we focused on predicting individual dynamic thermal sensation based on physiological and psychological data. We designed a smart face mask that can measure skin temperature (SKT) and exhaled breath temperature (EBT) and is powered by a rechargeable battery. Real-time human experiments were performed in a subway cabin with twenty male students under natural conditions. The data were collected using a smartphone application, and we created features using the wavelet decomposition technique. The bagged tree algorithm was selected to train the individual model, which showed an overall accuracy and f-1 score of 98.14% and 96.33%, respectively. An individual's thermal sensation was significantly correlated with SKT, EBT, and associated features.

Experimental investigation of the effect of surgical masks on outdoor thermal comfort in Xiamen, China.

The COVID-19 pandemic has significantly changed people's lifestyles, and wearing surgical masks in outdoor public spaces has become commonplace. However, few studies have explored the impact of wearing masks on outdoor thermal comfort in different seasons. From May 2021 to February 2022, a series of longitudinal experiments were conducted in Xiamen, China to examine the effect of wearing surgical masks on outdoor thermal comfort. Forty-two participants took part in the experiments with and without masks. During the experiments, the thermal perceptions of the subjects and environmental thermal parameters were collected. Differences in outdoor thermal comfort between subjects wearing masks and those not wearing masks were determined in summer, autumn, and winter. Results showed that 1) the subjects wearing masks had lower neutral temperatures, and this difference was particularly pronounced in summer and exacerbated by walking; 2) in warm environments, masks reduced thermal comfort, and discomfort associated with masks was worse when walking than when sitting; 3) wearing masks significantly worsened facial comfort and increased chest discomfort, as summer turned to winter, the impact of masks on facial comfort decreased; 4) radiation and air temperature were the environmental parameters with the greatest impact on outdoor thermal sensation. Subjects who wore masks preferred lower temperatures, radiation, and humidity, and higher wind speeds.

Indoor thermal comfort in a rural dwelling in southwest China.

Recently, indoor thermal comfort has received more scholarly attention than ever due to the COVID-19 pandemic and global warming. However, most studies on indoor thermal comfort in China concentrated on urban buildings in the east and north. The indoor thermal comfort of rural dwellers in southwest China is insufficiently investigated. Hence, this study assesses residents' indoor thermal comfort in a rural dwelling in Linshui, obtains the thermal neutral temperature of the rural area, and analyzes the thermal adaptation behavior of rural dwellers. The results reveal that the thermal neutral temperature of rural dwellers is 29.33°C (operative temperature), higher than that presented in previous studies based on the same climate region. Indoor thermal conditions in rural dwellings are relatively harsh, but various thermal adaptation behavior of rural dwellers significantly improve their ability to withstand the harsh conditions. When people live in an environment with a (relatively) constant climate parameter (e.g., humidity), their perception of that parameter seems compromised. Most rural dwellers are unwilling to use cooling equipment with high energy consumption. Therefore, more passive cooling measures are recommended in the design and renovation of rural dwellings.

Investigation of the effects of face masks on thermal comfort in Guangzhou, China.

Wearing masks to study and work places has become a daily protective measure during the COVID-19 pandemic. In the summer of 2021, environmental parameters were monitored, and students in a university library in Guangzhou, China, were surveyed to analyze the possible symptoms of wearing masks for a long time, and to assess the sensitivity of various body parts to the environmental parameters. Concurrently, the preference of subjects wearing masks for various environmental parameters was also analyzed. Additionally, the relationship between thermal sensation and thermal index was analyzed to identify acceptable and comfortable temperature ranges. The expected duration of wearing masks was counted. Subjects wearing masks had greater requirements for environmental comfort, and reported increased thermal discomfort of the face and head, compared to those without masks. More than 70% of the subjects wearing masks reported that they experienced discomfort on their faces. Among the subjects who experienced discomfort, 62.7% reported that facial fever was the main symptom; while some reported symptoms of dyspnea (25.4%) and rapid heartbeat (9.1%). More than 75% of the subjects were expected to wear masks for 2.0 h or less. Evaluation of environmental thermal sensation, including overall, facial, and head thermal sensation, differed among subjects who wore and did not wear masks. The indexes of neutral Operative temperature/Standard Effective Temperature (T op /SET*) and preferred T op /SET* were lower among subjects with masks than among those without masks. The neutral T op /SET* deviation was 0.3 °C, and the preferred T op /SET* deviation was 0.5 °C. Additionally, the acceptable and comfortable temperature zones differed between the two cases. The subjects who wore masks preferred colder temperatures. These findings indicated that the environmental parameters should be adjusted to improve the thermal comfort of the human body while wearing masks in work or study places.