Heat stress is a significant challenge in dairy farming systems. Dairy cows under heat stress will encounter impaired welfare leading to production losses. As the frequency and magnitude of heat ...stress events increase in the coming decades, a focus on heat stress reduction studies becomes important. Modelling and on-farm experiments have been used to assess the effects of heat stress on livestock over the last few decades. Mitigation solutions including optimal shed structure, ventilation, feeding regimes, farm management and genetic selection have all been explored. However, under different farm conditions, the heat tolerance and coping ability of dairy cows can vary significantly. Until now, the results from different mathematical models have provided a variety of heat stress thresholds for on-farm use. In practice, it is still costly to determine an accurate heat stress level in order to identify the mitigation requirements. This review summarises previous studies on the effects of heat stress on intensively reared dairy cows and different mitigation approaches. We have undertaken a comparative analysis of thermal indices, animal responses, and mitigation approaches. Recommendations are then given for developing a framework to enhance the measurement, assessment and mitigation of heat stress. Robust monitoring systems, big data analyses and artificial intelligence algorithms are needed for the future development of dynamic, self-calibrating model-based systems, which could provide real-time assessment and minimisation of heat stress.
•Devices for monitoring heat stress on cattle are assessed including IOT functions.•Complexity and inconsistency limit the usage of published thermal comfort index.•Fans plus misters are still the most cost effective heat stress mitigation approach.•Conceptual model for developing a globalised framework is proposed.
We identified physiological and thermal responses to different activity levels on a campus during summertime in Xi'an, a humid subtropical city in China. Physiological responses and thermal comfort ...of 54 healthy college students while undertaking different physical activities (light, moderate and vigorous intensities) in six campus open spaces were investigated using meteorological measures, longitudinal questionnaire surveys and physiological parameters. Physiological Equivalent Temperature (PET) and Universal Thermal Climate Index (UTCI) were chosen as the thermal indices, while blood pressure (BP), heart rate (HR) and skin temperature (ST) were selected as physiological evaluation measures. Results demonstrated that: 1) Types and proportions of thermal symptoms were positively related to outdoor spatial characteristics and physical activity levels. The proportion of thermal discomfort increased 33, 50 and 83% as activity intensities increased from light through moderate to vigorous. 2) BP and HR reflected human activity levels. HR clearly represented metabolic trends. 3) ST accurately represented physiological responses among spaces across activity levels. However, mean skin temperature (MST) was poorly related to thermal sensation vote (TSV). 4) As activity intensity ranged from light through moderate to vigorous, neutral UTCI declined by 27.6 °C, 25.6 °C, 22.0 °C, and neutral PET declined by 26.1 °C, 22.1 °C, 11.9 °C. 5) Outdoor spaces shaded by trees or pavilions were more comfortable for outdoor activities than these with low or middle SVF during summer.
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•We studied human physiological and thermal responses on a campus in Xi'an, China.•Thermal discomfort ratio increased from 33 to 83% as intensities ranged from light to vigorous.•MST at moderate and vigorous intensities decreased about 0.25–0.5 °C compared to light intensity.•As activity intensities ranged from light to vigorous, neutral PET decreased from 26.1 to 11.9 °C.•Neutral UTCI decreased from 27.6 to 22.0 °C as intensities ranged from light to vigorous.
Outdoor spaces play important roles in daily lives, and the use of these spaces is determined largely by outdoor thermal comfort. Few studies have been conducted on outdoor thermal comfort in ...northern China. Using microclimatic monitoring and subject interviews at a park in Tianjin, China, this investigation studied outdoor thermal comfort under different climate conditions. Although outdoor thermal environment varied greatly with air temperature from −5.0 to 34.5 °C, 83.3% of respondents consider it “acceptable”. Preferences in solar radiation, wind speed, and relative humidity were related to air temperature. The higher the air temperature was, the higher the wind speed and the lower the solar radiation and relative humidity desired by the occupants, and vice versa. The data were also used to evaluate three indices. The Universal Thermal Climate Index (UTCI) satisfactorily predicted outdoor thermal comfort, while the Predicted Mean Vote (PMV) overestimated it. The neutral physiological equivalent temperature (PET) range found in this study was 11–24 °C, which was lower than the ranges in Europe and Taiwan. Our study indicated that residents of Tianjin were more adapted to cold environment.
•We investigated outdoor thermal comfort in cold climate region in northern China.•Thermal sensation and overall comfort varied with the season.•The UTCI satisfactorily predicted thermal comfort, while the PMV overestimated it.•Neutral PET range in Tianjin is 11–24 °C.
The precise analysis of the usage of thermal indices to evaluate and create an acceptable space is a research hotspot as thermal comfort increasingly comes to be the center of attention. The accurate ...measurement and calculation of the metabolic rate should be a top priority in research because it is the most important component of thermal indexmodels. This study includes a literature survey of the relevant fields to properly comprehend the present developments and flaws in calculating the metabolic rate. The ultimate objective is to apply the growth of human metabolic science to logical urban development. First, the interaction between the thermal environment and thermal comfort was analyzed, and then, the influence of the human metabolic rate on thermal comfort was discussed. The results show that the dynamic change of metabolic rate is the key human factor that directly affects the thermal regulation, and indirectly affects the evaluation accuracy of the thermal evaluation index standard. Through an inductive analysis of metabolic rate measurement methods that are widely used in various environments, this study identifies several issues with the current utilization of portable metabolic monitoring instruments in dynamic thermal comfort research, highlighting their limitations in addressing accuracy, portability, economy, and other relevant aspects. An essential future effort in this study path will be the continued research and development of a more portable, more affordable, more direct, and more efficient customized metabolic rate monitoring equipment. In addition, the fact that metabolic rate is represented as a constant or its impact on thermal comfort as a single factor in existing thermal index models also frequently results in incorrect findings in outdoor research. The fundamental condition for enhancing thermal comfort index forecast accuracy is accurate and continuous tracking of metabolic rate.
The thermal index (TI) has been used as a relative indicator of thermal risk during diagnostic ultrasound examinations for many years. It is useful in providing feedback to the clinician or ...sonographer, allowing assessment of relative, potential risks to the patient of an adverse effect due to a thermal mechanism. Recently, several shortcomings of the TI formulations in quantifying the risk to the patient have been identified by members of the basic scientific community, and possible improvements to address these shortcomings have been proposed. For this reason, the Output Standards Subcommittee of the American Institute of Ultrasound in Medicine convened a subcommittee to review the strengths of the TI formulations as well as their weaknesses and proposed improvements. This article summarizes the findings of this subcommittee. After a careful review of the literature and an assessment of the cost of updating the TI formulations while maximizing the quality of patient care, the Output Standards Subcommittee makes the following recommendations: (1) some inconsistencies in the current TI formulations should be resolved, and the break point distance should be redefined to take focusing into consideration; (2) an entirely new indicator of thermal risk that incorporates the time dependence not be implemented at this time but be included in continuing efforts toward standards or consensus documents; (3) the exponential dependence of risk on temperature not be incorporated into a new definition of the TI formulations at this time but be included in continuing efforts toward standards or consensus documents; (4) the TI formulations not be altered to include nonlinear propagation at this time but be included in continuing efforts toward standards or consensus documents; and (5) a new indicator for risk from thermal mechanisms should be developed, distinct from the traditional TI formulations, for new imaging modalities such as acoustic radiation force impulse imaging, which have more complicated pulsing sequences than traditional imaging.
During the SARS-CoV-2 (COVID-19) pandemic, most citizens were cooperative towards the face-masking policy; however, undeniably, face masking has increased complaints of thermal discomfort to varying ...degrees and resulted in potential health hazards during summer. Thus, a thermal comfort survey was conducted under tree-shaded areas generally preferred by pedestrians to explore the thermal response of face-masked pedestrians. Thirty-two subjects, with and without masks, participated in walking experiments, and their thermal parameters and physiological indicators were recorded; moreover, the subjects were asked to fill in subjective questionnaires. The results showed that although tree shades significantly reduced the average radiant temperature, dampness in the mask may cause some discomfort symptoms, among which intense sweating (54.55%) and tachycardia (42.18%) accounted for the largest proportion. Based on thermal indices, it could be concluded that face-masking does not significantly affect the thermal comfort of subjects walking in shaded areas. Notably, a 30-min walk in tree-shaded areas with face masking does not adversely affect human health or quality of life. Thus, the present assessment of the thermal safety of humans in shaded environments provides reference data for determining thermal comfort levels during outdoor walking with face masking.
•The subjects wear face masks to simulate to explore the thermal response of face-masked pedestrians.•The differences of thermal sensation between wear masks and without masks while walking are determined.•The human body, while walking, was less sensitive to wetness than hotness.•Tsk could predict the thermal sensation of the human body while walking.
Camping has increasingly gained popularity as an outdoor leisure activity in China. This study investigated four spatial contexts within waterfront campsites in hot and humid regions, utilizing ...physical measurements and questionnaire surveys. Physiological equivalent temperature (PET) was employed to assess outdoor thermal comfort. Additionally, thermal index simulations were conducted using the ENVI-met model, establishing a linear relationship between simulated results and actual measurements. Results indicated: (1) Air temperature was the meteorological factor that significantly influenced campers' thermal sensations. (2) Campers in spaces with lower sky view factor (SVF) exhibited better adaptability to the thermal environment. (3) The thermal index simulated by ENVI-met overestimated participants' thermal sensations, leading to a proposed algorithm for refining the thermal index model. (4) Campers preferred low-intensity activities in low SVF spaces and moderate-to-high-intensity activities in high SVF spaces. The recommended campsite design involved a U-shaped planting arrangement and tall broadleaf tree species based on camper preferences. These findings assisted urban designers and planners in understanding and predicting campers' thermal comfort and adaptive behaviors in hot and humid regions, facilitating improvements in campsite design.
Today, the use of sensors and imaging techniques, which are used to obtain information about plants and soil in smart irrigation systems, is rapidly becoming widespread. This study aimed to ...investigate the usability of leaf turgor pressure and thermal images from plant-based monitoring techniques to detect water stress and the irrigation time of pepper (Capsicum annuum L. cv. "California Wonder") and to determine their relationship with physiological traits in Canakkale/Türkiye in 2017 and 2018. The four irrigation treatments (100%, 75%, 50%, and 25%) were applied in the experiment. Leaf turgor pressure (Pp), thermal images and physiological measurements were carried out during the growing season. Soil moisture and Pp were monitored in real time by remote. Thermal and physiological measurements were made before each irrigation. As a result of the study, the average evapotranspiration (ETc) was 697 mm, and the yield value was 83.7 t ha−1 under non-stress conditions. Depending on the decrease in ETc, yield values also decreased significantly. Leaf water potential and stomatal conductivity values were statistically different in all irrigation treatments. The change in the activity of catalase (CAT) due to water stress was greater than that of superoxide dismutase (SOD). In this case, it can be said that other physiological traits are more successful than SOD in distinguishing water stress. According to the regression models, significant relationships were determined between both the indices calculated from the thermal images and Pp, yield, and physiological traits. The predictive ability of Pp values has been strengthened with the addition of meteorological properties to the model in general. The highest correlation (R2 =0.63) was between Pp + meteorological properties and CAT. All the regression models between physiological traits and indices calculated from thermal images were statistically significant. The highest R2 values were obtained in August. In this month, the highest correlations were between Crop Water Stress Index (CWSIp) and leaf water potential / stomatal conductivity (R2 =0.91), IGp and stomatal conductivity (R2 =0.80). The predictive power of CWSIp was higher than Stomatal Conductivity Index (IGp). The experiment illustrated that Pp and temperature data, which are plant-based monitoring methods, have the potential to detect water stress in peppers.
•The pepper plant is very sensitive to water stress.•Instant monitoring of both the soil and the plant is quite important.•Stomatal conductance and leaf water potential are effective indicators of water stress.•Physiological traits can be monitored in real time using Pp probe.•Yield and physiological properties can be accurately predicted from thermal indices.
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