Main effects and interactions of multiple key factors related to thermal perception.

The real indoor environment involves the comprehensive interaction of multiple factors, and human subjective responses to different factors are influenced by various aspects such as physics, physiology, and psychology. The relative significance of various factors influencing different types of human subjective thermal perception, as well as the extent of their interactions, remains somewhat unclear. This investigation, leveraging the "Chinese Thermal Comfort Dataset," analyzed the integrated impact of basic thermal perception factors-temperature, humidity, air speed, as well as clothing insulation and metabolic rate-on subjective thermal perception. The findings underscored the definitive role of air temperature as the primary determinant of thermal sensation, with the impact of other factors generally remaining below 15 % of temperature. Nonetheless, the sensitivity of thermal sensation to temperature is significantly affected by other factors, demonstrating a significant interaction between temperature and different factors in influencing temperature sensation. Additionally, it was observed that significant differences (p < 0.001) in thermal comfort levels existed even at the same thermal sensation. For instance, in the state of thermal neutrality, occupants with relatively higher clothing insulation reported higher thermal comfort level (d = 0.40, p < 0.001) during the cooling season but lower thermal comfort level (d = 0.54, P < 0.001) during the heating season. Consequently, it can be deduced that when comprehensively considering the impact of multiple factors, evaluating the environment solely based on thermal sensation or thermal neutrality may prove insufficient.

Gender differences in thermal sensation and skin temperature sensitivity under local cooling.

Local cooling has proven to be an alternative to traditional comfort air conditioning to ensure users' thermal comfort while conserving energy. Few studies have investigated the gender differences in the applicable cooling temperatures and the applicable cooling locations and the differences in the sensitivity of skin temperature to thermal sensation under local cooling. Based on the design of orthogonal experiment, nine chamber experiments were conducted through different combinations of ambient temperature, cooling temperature, and cooling location. The subjective questionnaires and objective measurements were obtained in each experimental case. The results showed that the ambient temperature and the cooling location significantly affect the human overall thermal sensation of both genders under local cooling, while cooling temperature and cooling location significantly affect the local thermal sensation. For female, a neutral thermal sensation can be achieved by cooling the back at 24-26 °C when the ambient temperature is 31 °C. Back cooling at 22-26 °C is effective for male when the ambient temperature is 28 °C and 31 °C, and sole cooling with a higher cooling temperature is more acceptable at 34 °C. Moreover, female skin temperature is more sensitive to thermal sensation than that of males under local cooling. The upper arm skin temperature is most sensitive to thermal sensations for female, while the forearm skin temperature is most sensitive for male.

Characteristics of PM2.5 emissions from six types of commercial cooking in Chinese cities and their health effects.

Commercial kitchens may pose significant health risks to workers because they generate large quantities of fine particulate matter (PM2.5). In our study, the concentrations and emission rates of PM2.5 in cooking environments were measured for six types of commercial kitchens that used electricity and natural gas (including traditional Chinese kitchens, western kitchens, teppanyaki kitchens, fried chicken kitchens, barbecue kitchens, and hotpot cooking area). Furthermore, a preliminary health risk assessment of the chefs was undertaken using the annual PM2.5 inhalation and PM2.5 deposition rates into the upper airways and tracheobronchial and alveolar regions of the human body. Results showed that cooking in the teppanyaki kitchen generated the highest amount of PM2.5, with a mean emission rate of 7.7 mg/min and a mean mass concentration of 850.4 ± 533.4 µg/m³ in the breathing zone. Therefore, teppanyaki kitchens pose highest PM2.5 exposure risks to chefs, with the highest rate of PM2.5 deposition in the upper airways (6.38 × 105 µg/year), followed by Chinese kitchens. The PM2.5 concentrations and emission rates of each kitchen varied greatly with the dishes cooked. The mean PM2.5 concentration was the highest during Chinese stir-frying, with the peak concentration reaching more than 20,000 µg/m3, followed by pan-frying, deep-frying, stewing, and boiling. A rise in PM2.5 concentration was also observed during the start of stir-frying and in the middle to late stages of pan-frying and grilling meat. The results obtained in our study may contribute in understanding the characteristics of PM2.5 emissions from various types of commercial kitchens and their health effects.