Comparison between male and female subjective estimates of thermal effects and sensations

Sex differences in thermal sensitivity and perception: Implications for behavioral and autonomic thermoregulation

Temperature sensitive receptors in the skin and deep body enable the detection of the external and internal environment, including the perception of thermal stimuli. Changes in heat balance require autonomic (e.g., sweating) and behavioral (e.g., seeking shade) thermoeffector initiation to maintain thermal homeostasis. Sex differences in body morphology can largely, but not entirely, account for divergent responses in thermoeffector and perceptual responses to environmental stress between men and women. Thus, it has been suggested that innate differences in thermosensation may exist between men and women. Our goal in this review is to summarize the existing literature that investigates localized and whole-body cold and heat exposure pertaining to sex differences in thermal sensitivity and perception, and the interplay between autonomic and behavioral thermoeffector responses. Overall, it appears that local differences in thermal sensitivity and perception are minimized, yet still apparent, when morphological characteristics are well-controlled. Sex differences in the early vasomotor response to environmental stress and subsequent changes in blood flow likely contribute to the heightened thermal awareness observed in women. However, the contribution of thermoreceptors to observed sex differences in thermal perception and thermoeffector function is unclear, as human studies investigating these questions have not been performed.

Thermoregulation and thermal sensation during whole-body water immersion at different water temperatures in healthy individuals: A scoping review

BACKGROUND

Severe thermal discomfort may increase risk of drowning due to hypothermia or hyperthermia from prolonged exposure to noxious water temperatures. The importance of using a behavioral thermoregulation model with thermal sensation may predict the thermal load that the human body receives when exposed to various immersive water conditions. However, there is no thermal sensation "gold standard" model specific for water immersion. This scoping review aims to present a comprehensive overview regarding human physiological and behavioral thermoregulation during whole-body water immersion and explore the feasibility for an accepted defined sensation scale for cold and hot water immersion.

METHODS

A standard literary search was performed on PubMed, Google Scholar, and SCOPUS. The words "Water Immersion," "Thermoregulation," "Cardiovascular responses" were used either as independent searched terms and MeSH terms (Medical Subject Headings) or in combination with other text words. The inclusion criteria for clinical trials terms to thermoregulatory measurements (core or skin temperature), whole-body immersion, 18-60 years old and healthy individuals. The prementioned data were analyzed narratively to achieve the overall study objective.

RESULTS

Twenty-three published articles fulfilled the review inclusion/exclusion criteria (with nine measured behavioral responses). Our outcomes illustrated a homogenous thermal sensation in a variety of water temperatures ranges, that was strongly associated with thermal balance, and observed different thermoregulatory responses. This scoping review highlights the impact of water immersion duration on human thermoneutral zone, thermal comfort zone, and thermal sensation.

CONCLUSION

Our findings enlighten the significance of thermal sensation as a health indicator for establishing a behavioral thermal model applicable for water immersion. This scoping review provides insight for the needed development of subjective thermal model of thermal sensation in relation to human thermal physiology specific to immersive water temperature ranges within and outside the thermal neutral and comfort zone.

Thermal perception and lung function: a panel study in young adults with exercise under high outdoor temperature

It has been observed that high temperature exposure is associated with a reduction in lung function and some possible biological mechanisms have been suggested. However, it is unclear if thermal perception plays a role in the association. From September 3rd to 15th, 2018, in Guangzhou, China, we repeatedly measured daily thermal perception and lung function among 126 participants with outdoor military training. We performed a linear mixed model and stratified analyses by the origin of students, gender, and the training period to evaluate the effects of thermal perception on lung function. A total of 399 measurements were collected. Per vote increase in thermal sensation vote towards the "hot" direction was associated with a - 0.04 L (95% CI: - 0.08 to - 0.01) decrease in forced vital capacity (FVC), and - 0.04 L (95% CI: - 0.08 to - 0.01) decrease in forced expiratory volume in 1 s (FEV₁). Per grade increase towards the "very uncomfortable" direction for thermal comfort vote was associated with an increased percentage of forced expiratory volume in 1 s (FEV₁%) by 1.52% (95% CI: 0.18 to 2.86). For thermal preference, with preferred cooler vote increased by one level, FVC and FEV₁ decreased by - 0.05 L/s (95% CI: - 0.08 to - 0.02) and - 0.05L/s (95% CI: - 0.08 to - 0.02), respectively. The effects of thermal perception on lung function were stronger among non-local and in the first week of training. Our study suggests that in the same high-temperature environment, thermal perception is associated with lung function, even in healthy adults.

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.

Quantitative Investigation of Body Part Selection for Data-Driven Personal Overall Thermal Preference Prediction

Personal thermal preference information can help to create a building environment that satisfies all staff, instead of an environment that only satisfies most people, to enhance personal thermal comfort. Research has shown that thermal preference can be predicted using parameters that are based on various local body parts, but the selected body parts are often different. Using too many body parts for the measurements leads to high costs, while using too few body parts results in large errors. In this study, 19 adult subjects (8 females and 11 males) were recruited, their overall and local thermal preferences were surveyed, and the skin temperature of seven body parts were measured. A machine learning algorithm, random forest, was employed to analyse the contributions of different body parts. Three criteria (the best combination, fewest combination, and common combinations) were employed to select body parts to use to establish thermal preference models for individuals and groups. The results show that the prediction power of these combinations reached 0.91 ± 0.07 (accuracy), 0.75 ± 0.16 (Cohen’s kappa), and 0.87 ± 0.09 (AUC) when using 2–8 body parts. The common combinations are recommended for their balance of their prediction power and the number of local body parts involved. This study offers a reference for efficient and economic measurements for thermal comfort research in building environments.

Effects of body geometry, body composition, cardio-pulmonary capacity, and fitness on young men's thermal preference

This paper investigated principal parameters affecting individual differences of thermal preference. 36 male college students were selected from three thermal preference groups by a questionnaire, including 10 of cool preference (Gcp), 17 of neutral preference (Gnp), and 9 of warm preference (Gwp). Subsequently, their thermal preferences were further examined by a human trial in a climate chamber. Once significant differences were found between groups, subjects' 57 parameters, including body geometry, body composition, cardio-pulmonary capacity, and physical fitness, were measured. Compared to Gwp, Gcp had higher weight (80.0 vs. 64.2 kg), body mass index (BMI) (26 vs. 20.8 kg·m^-2 ), body surface area (BSA) (1.94 vs. 1.78 m² ), waist-to-hip ratio (WHR) (87.29% vs. 80.23%), body circumferences (except for forearm circumference), skinfold thickness of all the local parts, volume of expired air (VE) (50.97 vs. 40.81 L/min), and body fat rate (BFR) (24.44% vs. 14.07%), but had a lower specific surface area (SSA) (0.02477 vs. 0.02791 m² /kg), resting metabolic rate (RMR) per kilogram (1.21 vs. 1.47 W/kg), diastolic blood pressure (DBP) (65.30 vs. 74.69 mmHg), and percentages of muscle (71.17% vs. 80.95%), total water (55.35% vs. 63.14%), skeletal muscle (42.47% vs. 47.94%), protein (14.90% vs. 16.94%), inorganic salt (5.29% vs. 5.86%), and bone mineral (0.044% vs. 0.048%). Among these parameters, body fat and SSA played a dominant role (accounting for 85.76%) in explaining individual differences in thermal preference.

Regular and temporary occupants' perceptions of satisfaction in tertiary education buildings

There is little knowledge about occupants' satisfaction when diverse end users coexist in the same building. This paper presents the results of a survey administered to 1013 occupants in 43 academic buildings in Spain, with the aim to reveal the perception of the indoor environmental quality and workplace ergonomics of both lecturers and students. The results revealed that light adequacy, cleanliness and acoustics in classrooms are perceived differently by lecturers and students. Results also revealed no gender differences in satisfaction with all aspects of comfort in classrooms. However, in offices, air quality, thermal sensation in winter and adequacy of space were perceived differently by male and female. The findings will be of interest for tertiary building maintenance, design teams and ergonomists to enhance comfort in both groups of end users. Practitioner Summary: There are no reported studies on how groups of occupants (regular and temporary) perceive comfort in relevant aspects such as acoustics, lighting, space adequacy, cleanliness, and ergonomics. The survey results with 1013 occupants revealed that regular users tend to be less satisfied than temporary users in rooms where they cohabit. Abbreviations: POE: post-occupancy evaluation; HVAC: heating, ventilation and air conditioning; AQ: air quality; IEQ: indoor environmental quality; TS: thermal sensation.

Factors Affecting Occupants’ Satisfaction in Governmental Buildings: The Case of the Kingdom of Bahrain

Satisfaction is a very important factor in improving productivity and performance in the work environment. This study aims to investigate the levels of occupants’ satisfaction with the indoor environmental quality (IEQ) in the governmental buildings in the Kingdom of Bahrain and to investigate the impact of occupants’ demographics and building attributes (non-IEQ factors) on these levels. For these purposes, the study used a questionnaire that has 17 indoor environmental quality (IEQ) factors in addition to a group of non-IEQ factors. The questionnaire was distributed by hand or using email to 279 employees in the Bahraini governmental sector. The findings of the study revealed that occupants in the Bahraini governmental buildings are not strongly satisfied with IEQ factors, especially with sound privacy, followed by visual privacy and amount of space, and then noise levels. The findings also showed that for most IEQ factors, men are more satisfied than women are, those who work in enclosed private offices are more satisfied than those who work in open-plan offices, and those who have central air-conditioning at their workplace are more than those who have a wall-mounted air conditioner. The impact of age, nature of work, duration of working in the current building and at the current workstation, weekly working hours, and proximity to the window were also investigated. Accordingly, a group of recommendations was suggested aiming to improve the levels of occupants’ satisfaction.

Differences between sexes in thermoregulatory responses and exercise time during endurance exercise in a hot environment following pre-cooling with ice slurry ingestion

This study aimed to examine differences between sexes in thermoregulatory responses and exercise time after ice slurry ingestion in a hot environment. Twenty-four healthy adults (male n = 12, body weight (BW) = 65.8 ± 10.3; female n = 12, BW = 58.2 ± 10.0) ingested 7.5 g/kg of either ice slurry at -1 °C (ICE) or control water at 20 °C (CON) before cycling at 55%VO₂ max in a hot environment (controlled at 38 °C, 40% relative humidity). Rectal (Tre) and skin (Tsk) temperature, heart rate, sweat rate, respiratory gases, ratings of thermal sensation (TS), thermal comfort (TC), and rating of perceived exertion (RPE) were measured. Ice slurry did not improve exercise time in both sexes despite Tre was significantly lower in ICE than CON in both sexes. Tre, Tsk, HR, sweat rate and TS did not differ between sexes. TC and RPE in ICE were significantly higher during exercise in males than in females. In conclusion, there were no sex differences in the effects of pre-cooling with ice slurry ingestion; however, pre-cooling with ice slurry may be more effective in mitigating ratings of TC and RPE in females than males.

Assessment of Indoor Air Quality and Users Perception of a Renovated Office Building in Manchester

Building renovations can adversely affect building occupants through the release of biological contaminants, gases and particulates. In this study, the research aim was to monitor the air quality of a renovated building and assess the impact of sick building syndrome (SBS) on the occupants. Post occupancy monitoring of the building was carried out after two months occupancy for the following environmental parameters: airborne microflora using an air sampler (SAS super 180) and a hand-held monitoring device (Graywolf advance sense IQ-610) to measure total volatile organic compounds (TVOC), CO₂, CO and temperature and relative humidity in each office environment. In addition, an online (Qualtrics) structured questionnaire was used to assess occupants’ perceptions of the indoor environment. Results of the airborne flora showed 833 cfu/m³ recovered on a Malt Extract Agar (MEA) plate in the morning and 1213 cfu/m³ in the afternoon. A similar result was noticed on a Plate Count Agar (PCA) plate during the morning period (731 cfu/m³) and afternoon (1358 cfu/m³). Results of TVOC monitored over one week showed that the first two days of monitoring had a high reading that peaked at 10,837 ppb and that the CO₂ concentration during that period was 1163 ppm. Online questionnaire analysis indicates that a majority of the staff who took part in the survey experienced some form of health abnormality, including headache, shortness of breath, itchy eyes/ears, loss of concentration and so on, especially in the first few weeks of returning to the office. The results from the study indicate that a large proportion (41%) of the respondents experienced thermal discomfort as a result of varying room temperature during their working hours. A high number of female participants experienced some form of SBS as compared to their male counterparts. The study findings show a direct relationship between high airborne mold counts, TVOC and adverse staff health perception of the building. The study raised a number of opportunities for estate managers to improve building performance based on occupants’ preferences.

TRPM2 and warmth sensation

The abilities to detect warmth and heat are critical for the survival of all animals, both in order to be able to identify suitable thermal environments for the many different activities essential for life and to avoid damage caused by extremes of temperature. Several ion channels belonging to the TRP family are activated by non-noxious warmth or by heat and are therefore plausible candidates for thermal detectors, but identifying those that actually regulate warmth and heat detection in intact animals has proven problematic. TRPM2 has recently emerged as a likely candidate for the detector of non-noxious warmth, as it is expressed in sensory neurons, and mice show deficits in the detection of warmth when TRPM2 is genetically deleted. TRPM2 is a chanzyme, containing a thermally activated TRP ion channel domain attached to a C-terminal motif, derived from a mitochondrial ADP ribose pyrophosphatase, that confers on the channel sensitivity to ADP ribose and reactive oxygen species such as hydrogen peroxide. Several open questions remain. Male mammals prefer cooler environments than female, but the molecular basis of this sex difference is unknown. TRPM2 plays a role in regulating body temperature, but are other warmth-detecting mechanisms also involved? TRPM2 is expressed in autonomic neurons, but does it confer a sensory function in addition to the well-known motor functions of autonomic neurons? TRPM2 is thought to play important roles in the immune system, in pain and in insulin secretion, but the mechanisms are unclear. TRPM2 has to date received less attention than many other members of the TRP family but is rapidly assuming importance both in normal physiology and as a key target in disease pathology.

Gender differences in public office workers' satisfaction, subjective symptoms and musculoskeletal complaints in workplace and office environments

This study investigates differences between male and female public office workers' satisfaction levels, sick building syndrome (SBS) symptoms and musculoskeletal disorder (MSD) complaints in workplace and office environments. Questionnaire surveys were performed in 30 offices from 15 public institutions. Male and female workers of the same age were coupled and selected from each office, gathering a total of 120 male and 120 female subjects. The results show that differences exist between genders in noise and lighting satisfaction levels, SBS-related symptoms (eye, nose, skin) and MSD complaints of hand/wrist/finger, while there is no difference in overall satisfaction level of office environments. The study also suggests that office design for public office workers should take into account gender differences in preventing MSDs and also SBS. The findings of this study are expected to serve as basic data for designing effective public office environments.

A field study on thermal comfort in an Italian hospital considering differences in gender and age

The hospital is a thermal environment where comfort must be calibrated by taking into account two different groups of people, that is, patients and medical staff. The study involves 30 patients and 19 medical staff with a view to verifying if Predicted Mean Vote (PMV) index can accurately predict thermal sensations of both groups also taking into account any potential effects of age and gender. The methodology adopted is based on the comparison between PMV values (calculated according to ISO 7730 after having collected environmental data and estimated personal parameters) and perceptual judgments (Actual Mean Vote, AMV), expressed by the subjects interviewed. Different statistical analyses show that PMV model finds his best correlation with AMV values in a sample of male medical staff under 65 years of age. It has been observed that gender and age are factors that must be taken into account in the assessment of thermal comfort in the hospital due to very weak correlation between AMV and PMV values.

Investigation of gender difference in human response to temperature step changes

The purpose of this study was to examine gender difference in human response to temperature step changes. A total of three step-change conditions (S5: 32 °C-37 °C-32 °C, S11: 26 °C-37 °C-26 °C, and S15: 22 °C-37 °C-22 °C) were designed and a laboratory experiment with 12 males and 12 females was performed. Results of this study support our hypothesis that females differ from males in human response to sudden temperature changes from the perspectives of psychology, physiology and biomarkers. Females are more prone to show thermal dissatisfaction to cool environments while males are more likely to feel thermal discomfort in warm environments. It is logical that men have a stronger thermoregulation ability than women as male skin temperature change amplitude is smaller while the time to be stable for skin temperature is shorter than that of females after both up-steps and down-steps. In S15, males witnessed a more intensive decrease in RMSSD while females underwent a remarkable instant reduce in oral temperatures after the up-step. Marginal significance was observed in male IL-6 before and after the up-step in S15 while female IL-6 prominently increased after the down-step in S15.

Evaluation of thermal comfort in university classrooms through objective approach and subjective preference analysis

Assessing thermal comfort becomes more relevant when the aim is to maximise learning and productivity performances, as typically occurs in offices and schools. However, if, in the offices, the Fanger model well represents the thermal occupant response, then on the contrary, in schools, adaptive mechanisms significantly influence the occupants' thermal preference. In this study, an experimental approach was performed in the Polytechnic University of Bari, during the first days of March, in free running conditions. First, the results of questionnaires were compared according to the application of the Fanger model and the adaptive model; second, using a subjective scale, a complete analysis was performed on thermal preference in terms of acceptability, neutrality and preference, with particular focus on the influence of gender. The user possibility to control the indoor plant system produced a significant impact on the thermal sensation and the acceptability of the thermal environment. Gender was also demonstrated to greatly influence the thermal judgement of the thermal environment when an outdoor cold climate occurs.

Too hot to sleep? Sleep behaviour and surface body temperature of Wahlberg's Epauletted Fruit Bat

The significance of sleep and factors that affect it have been well documented, however, in light of global climate change the effect of temperature on sleep patterns has only recently gained attention. Unlike many mammals, bats (order: Chiroptera) are nocturnal and little is known about their sleep and the effects of ambient temperature (T_a) on their sleep. Consequently we investigated seasonal temperature effects on sleep behaviour and surface body temperature of free-ranging Wahlberg’s epauletted fruit bat, Epomophorus wahlbergi, at a tree roost. Sleep behaviours of E. wahlbergi were recorded, including: sleep duration and sleep incidences (i.e. one eye open and both eyes closed). Sleep differed significantly across all the individuals in terms of sleep duration and sleep incidences. Individuals generally spent more time awake than sleeping. The percentage of each day bats spent asleep was significantly higher during winter (27.6%), compared with summer (15.6%). In summer, 20.7% of the sleeping bats used one eye open sleep, and this is possibly the first evidence of one-eye-sleep in non-marine mammals. Sleep duration decreased with extreme heat as bats spent significantly more time trying to cool by licking their fur, spreading their wings and panting. Skin temperatures of E. wahlbergi were significantly higher when T_a was ≥35°C and no bats slept at these high temperatures. Consequently extremely hot days negatively impact roosting fruit bats, as they were forced to be awake to cool themselves. This has implications for these bats given predicted climate change scenarios.

Temperature rating prediction of Tibetan robe ensemble based on different wearing ways

Each piece of Western clothing has a unique temperature rating (TR); however, based on different wearing ways, one Tibetan robe ensemble can be used in various environments of the Tibetan plateau. To explain this environmental adaptation, thermal insulations and TR values of Tibetan robe ensembles in three typical wearing ways were measured by manikin testing and wearing trials, respectively. The TR prediction models for Tibetan robe ensembles were built in this research. The results showed that the thermal insulations of Tibetan robe ensembles changed from 0.26 clo to 0.91 clo; the corresponding TRs ranged from 9.90 °C to 16.86 °C because of different wearing ways. Not only the thermal insulation, but also the ways of wearing Tibetan robes was important to determining their TR values. The three TR models and a triangle area for each piece of Tibetan clothing explained its positive adaptation into the environment; this was different from the current TR models for Western clothing.

Thermal comfort and gender: a literature review

This review examines scientific literature on the effect of gender on indoor thermal comfort. Gender differences have been generally considered to be small and insignificant but this review shows that a growing number of studies have found significant differences in thermal comfort between the genders. Clearly more than half of the laboratory and field studies have found that females express more dissatisfaction than males in the same thermal environments. Very few studies have found males to be more dissatisfied than females. A meta-analysis shows that females are more likely than males to express thermal dissatisfaction (ratio: 1.74, 95% confidence interval: 1.61-1.89). However, most studies found no significant difference in neutral temperatures between the genders. Females are more sensitive than males to a deviation from an optimal temperature and express more dissatisfaction, especially in cooler conditions.

PRACTICAL IMPLICATIONS

We should no longer neglect the more rigorous requirements that females have for indoor thermal environments. Gender differences indicate that females have, on average, a greater need for individual temperature control and adaptive actions than males. The results of this review suggest that females should primarily be used as subjects when examining indoor thermal comfort requirements, as if females are satisfied it is highly probable that males are also satisfied.

Cognitive function in hot environments: a question of methodology

The physiological responses of thermal stress and its consequences on health have been well documented. However, the effect on cognitive function remains equivocal despite a substantial number of studies conducted in the area. Methodological discrepancies across different studies have made it difficult to conclude whether or not heat exposure per se has an adverse effect upon cognitive function and under what specific environmental and physiological conditions these alterations appear. This article gives an overview of the different confounding factors that have made it difficult to make conclusive interpretations. In addition, the current state of knowledge is presented and discussed with reference to the Global Workspace theory. Although previously presented conclusions are promising, much remains to be completed before understanding the mechanisms that could explain the relationship between heat exposure and cognitive function. Finally, recommendations are presented for further research in this area.

Effects of heating appliances with different energy efficiencies on associations among work environments, physiological responses, and subjective evaluation of workload

To clarify the association between heat stress, physiological responses and subjective workload evaluations in kitchens using an induction heating stove (IH stove) or gas stove. The study design was an experimental trial involving 12 young men. The trial measured ambient dry-bulb temperature, globe temperature, wet-bulb globe temperature (WBGT) and relative humidity; the subjects' weight, heart rate, blood pressure, oxygen uptake, amount of activity, body temperature, subjective awareness of heat and workload before and after mock cooking for 30 min. The IH stove insignificantly increased heat indicators in the work environment and workers showed lower oxygen uptake, skin temperature, subjective awareness of heat and workload after heat exposure. Both physiological load and subjective awareness of heat and workload were slight in kitchens using the IH stove, which provided a better work environment.

An investigation of heat stress effects on time-sharing performance

A study was conducted to investigate the effects of heat stress on time-sharing performance. Twelve participants performed three dual-task scenarios and a multiple-task scenario for 2 h in each of six climates. The climates were obtained by generating each of three wet bulb globe temperatures (WBGT; 22, 28 and 34 degrees C) with two relative humidity levels (30 and 70%). The dual tasks selected from the Criterion Task Set (CTS) were: (1) display monitoring with mathematical processing; (2) memory search with mathematical processing; and (3) unstable tracking with memory search. The multiple task scenario was generated using the SYNTASK software. The results indicated a significant heat stress effect on CTS display monitoring and unstable tracking performance and on the SYNTASK visual monitoring and auditory discrimination tasks. Additionally, at 34 degrees C WBGT, 70% relative humidity was more detrimental to performance than 30% relative humidity. Results were interpreted using the Maximal Adaptability Model and Shingledecker's information processing stage/resource framework. To describe the results in an orderly manner, the authors propose the concept of heat stress selectivity effects. In addition, the results were used to evaluate whether the most recent NIOSH recommended heat stress standard, which is based solely on physiological and medical criteria, protects time-sharing performance. It was concluded that the NIOSH criterion does offer protection up to 28 degrees C WBGT.