Humid Heat Research Articles

Ultrasound Measurements of Subcutaneous Fat Thickness Are Robust Against Hydration Changes.

Ultrasound is an appealing tool to assess body composition, combining the portability of a field method with the accuracy of a laboratory method. However, unlike other body composition methods, the effect of hydration status on validity is unknown. This study evaluated the impact of acute hydration changes on ultrasound measurements of subcutaneous fat thickness and estimates of body fat percentage. In a crossover design, 11 adults (27.1 ± 10.5years) completed dehydration and hyperhydration trials to alter body mass by approximately ±2%. Dehydration was achieved via humid heat (40 °C, 60% relative humidity) with exercise, whereas hyperhydration was via ingestion of lightly salted water. Ultrasound measurements were taken at 11 body sites before and after each treatment. Participants lost 1.56 ± 0.58kg (-2.0 ± 0.6%) during the dehydration trial and gained 0.90 ± 0.21kg (1.2 ± 0.2%) during the hyperhydration trial even after urination. The sum of fat thicknesses as measured by ultrasound differed by <0.90mm across trials (p = .588), and ultrasound estimates of body fat percentage differed by <0.5% body fat. Ultrasound measures of subcutaneous adipose tissue were unaffected by acute changes in hydration status by extents beyond which are rare and overtly self-correcting, suggesting that this method provides reliable and robust body composition results even when subjects are not euhydrated.

In vitro growth response of Patchouli (Pogostemon cablin) cultured in medium containing Methylobacterium spp. filtrate

Mass seeds production through micropropagation can support modern agriculture, but this technique is expensive and largely determined by a medium formulation. The addition of synthetic Plant Growth Regulator (PGR) has a residual effect, meanwhile natural PGRs is more secure but expensive. In vitro testing of PGR activity obtained from bacteria was the first step to substituted synthetic PGRs to become nature PGR. Research to observe PGR activity obtained from four strains of Methylobacterium spp that had been analyzed of the capability of PGRs synthesis was done on in vitro patchouli cultured. There are three activities: 1) The sterilized technique of filtrate using filtration techniques, humid heat, and a combination of both; 2) Testing of Methylobacterium spp. from that production of cytokinins and compared its activity with commercial PGRs (BA and zeatin); and 3) auxin (NAA and IAA). The research showed that strain TD-J2 filtrate added to medium was similar to BA activities, and TD-J7 was similar to zeatin. Auxin activity derived from strain TD-J10 showed the capacity to induces root formation. The research result indicates that synthesis PGR derived from Methylobacterium spp. has similar activity with commercial PGRs.

Rising Planetary Boundary Layer Height over the Sahara Desert and Arabian Peninsula in a Warming Climate

AbstractTurbulent mixing in the planetary boundary layer (PBL) governs the vertical exchange of heat, moisture, momentum, trace gases, and aerosols in the surface–atmosphere interface. The PBL height (PBLH) represents the maximum height of the free atmosphere that is directly influenced by Earth’s surface. This study uses a multidata synthesis approach from an ensemble of multiple global datasets of radiosonde observations, reanalysis products, and climate model simulations to examine the spatial patterns of long-term PBLH trends over land between 60°S and 60°N for the period 1979–2019. By considering both the sign and statistical significance of trends, we identify large-scale regions where the change signal is robust and consistent to increase our confidence in the obtained results. Despite differences in the magnitude and sign of PBLH trends over many areas, all datasets reveal a consensus on increasing PBLH over the enormous and very dry Sahara Desert and Arabian Peninsula (SDAP) and declining PBLH in India. At the global scale, the changes in PBLH are significantly correlated positively with the changes in surface heating and negatively with the changes in surface moisture, consistent with theory and previous findings in the literature. The rising PBLH is in good agreement with increasing sensible heat and surface temperature and decreasing relative humidity over the SDAP associated with desert amplification, while the declining PBLH resonates well with increasing relative humidity and latent heat and decreasing sensible heat and surface warming in India. The PBLH changes agree with radiosonde soundings over the SDAP but cannot be validated over India due to lack of good-quality radiosonde observations.

Looking ahead of 2021 Tokyo Summer Olympic Games: How Does Humid Heat Affect Endurance Performance? Insight into physiological mechanism and heat-related illness prevention strategies.

The combination of high humidity and ambient temperature of the 2021 Tokyo Summer Olympic Game will undoubtfully result in greater physiological strains and thereby downregulates the endurance performance of athletes. Although many research studies have highlighted that the thermoregulatory strain is greater when the environment is hot and humid, no review articles have addressed the thermoregulatory and performance differences between dry and humid heat and such lack of consensuses in this area will lead to increase the risk of heat-related injuries as well as suboptimal preparation. Furthermore, specific strategies to counteract this stressful environment has not been outlined in the current literature. Therefore, the purposes of this review are: 1) to provide a clear evidence that humid heat is more stressful than dry heat for both male and female athletes and therefore the preparation for the Tokyo Summer Olympic should be environmental specific instead of a one size fits all approach; 2) to highlight why female athletes may be facing a disadvantage when performing a prolonged endurance event under high humidity environment and 3) to highlight the potential interventional strategies to reduce thermal strain in hot-humid environment. The summaries of this review are: both male and female should be aware of the environmental condition in Tokyo as humid heat is more stressful than dry heat; Short-term heat acclimation may not elicit proper thermoregulatory adaptations in hot-humid environment; cold water immersion with proper hydration and some potential per-cooling modalities may be beneficial for both male and female athletes in hot-humid environment.

Sodium tungsten bronze (NaxWO3)-doped near-infrared-shielding bulk glasses for energy-saving applications

Tungsten bronze coatings and films have attracted global attention for their applications in near-infrared (NIR)-shielding windows. However, they are unstable in strong ultraviolet, humid heat, alkaline and/or oxidizing environments and are difficult to be coated on glass surfaces with complex shape. Here, we address these limitations by doping sodium tungsten bronze (NaxWO3) into bulk glasses using a simple glass melting method. X-ray diffraction, Raman spectroscopy, X-ray photoelectron spectroscopy, TEM and SEM-EDS characterization confirmed the presence of sodium tungsten bronze (NaxWO3) functional units inside the 34SiO2-38B2O3-28NaF glass matrix. Because the functional units are well protected by the glass matrix, the fabricated glasses are stable under hot, humid, oxidizing conditions, as well as under ambient conditions, with no change after 360 days. The NIR-shielding performance of these glasses can be adjusted to as high as 100 % by varying WOx concentration (2−8 mol%) and quenching temperature (1000−1400 °C). With a content of 6 mol% WOx and a quenching temperature of 1000 °C, the bulk glass shows 63 % transmission of visible light and only 11 % transmission of NIR light at 1100 nm. Thermal insulation experiments show that the NIR-shielding performance of the glasses are far superior to commercial soda lime window glass or indium-doped tin oxide (ITO) glass, and comparable to cesium tungsten bronze coated glass. The novel bulk glasses have higher stability, simpler processing, and can be easily made into complex shapes, making them excellent alternative materials for energy-saving glasses.

Perspectiva de la práctica clínica de fisioterapeutas colombianos en el manejo de la disfunción de la articulación sacroilíaca. Estudio descriptivo

Background and aimSacroiliac joint dysfunction (SIJD) is characterized by hypermobility or hypomobility of the joint and could be present in 13%–30% of people with low back pain of idiopathic origin. Therefore, it was important to analyse the physiotherapeutic clinical approach for patients diagnosed with SIJD in Bucaramanga (Colombia). MethodsAn observational descriptive cross-sectional study was conducted. The information was collected through a 31-question web survey, with face and content validation. Sociodemographic data, data on the training of the therapists and evaluation and intervention procedures used in the consultation were included. Results147 physiotherapists participated, 86.4% were women, 22.5% with postgraduate training. Seventy point four percent recognized SIJD as cause of low back pain and 43.5% stated that they did not use a specific test to diagnose SIJD. The most reported treatment modalities were therapeutic exercise, electrotherapy, humid heat, and massage. ConclusionsMost of the participants recognize SIJD as a cause of low back pain. Pain provocation tests were not used by most of the participants. Neither was the use of lumbopelvic stabilization exercises reported, required in SIJD rehabilitation. These findings show there is a need for training for the physiotherapists who participated in the study in the diagnosis and treatment of people with SIJD, to improve the recovery and quality of life of this population.

Dihydromyricetin attenuates heat stress-induced apoptosis in dairy cow mammary epithelial cells through suppressing mitochondrial dysfunction

It is well known that the dairy cow production is very sensitive to environmental factors, including high temperature, high humidity and radiant heat sources. High temperature-induced heat stress is the main environmental factor that causes oxidative stress and apoptosis, which affects the development of mammary glands in dairy cows. Dihydromyricetin (DMY) is a nature flavonoid compound extracted from Ampelopsis grossedentata; it has been shown to have various pharmacological functions, such as anti-inflammation, antitumor and liver protection. The present study aims to evaluate the protective effect of DMY on heat stress-induced dairy cow mammary epithelial cells (DCMECs) apoptosis and explore the potential mechanisms. The results show that heat stress triggers heat shock response and reduces cell viability in DCMECs; pretreatment of DCMECs with DMY (25 μM) for 12 h significantly alleviates the negative effects of heat stress on cells. DMY can provide cytoprotective effects by suppressing heat stress-caused mitochondrial membrane depolarization and mitochondrial dysfunction, Bax and Caspase 3 activity, and modulation of oxidative enzymes, thereby preventing ROS production and apoptosis in DCMECs. Importantly, DMY treatment could attenuate heat stress-induced mitochondrial fragmentation through mediating the expression of mitochondrial fission and fusion-related genes, including Dynamin related protein 1 (Drp1), Mitochondrial fission 1 protein (Fis1), and Mitofusin1, 2 (Mfn1, 2). Above all, our findings demonstrate that DMY could protect DCMECs against heat stress-induced injury through preventing oxidative stress, the imbalance of mitochondrial fission and fusion, which provides useful evidence that DMY can be a promising therapeutic drug for protecting heat stress-induced mammary glands injury and mastitis.

Evaluation of extreme temperature in multi-RCM simulations over CORDEX-East Asia phase II domain

In this study, the extreme temperature in high-resolution hindcast simulations conducted by three reanalysis-driven regional climate models (WRF, RegCM4 and CCLM) is evaluated during the period of 1989–2009. We select 10 extreme temperature indices recommended by the Expert Team on Climate Change Detection and Indices to compare the simulations with the CN05.1 dataset. In addition, apparent temperature (AT) combining relative humidity and air temperature is applied to define the humid heat wave indices. The results show that the regional climate models (RCMs) can skillfully reproduce the spatial distribution and the probability density function of daily maximum temperature (Tmax) and minimum temperature (Tmin) in spite of some biases in certain ranges and regions. For the intensity indices (TXx, TNn, TXn, TNx), the RCMs demonstrate very high spatial correlations with the observation, but they have difficulties in reproducing the interannual variations of these indices. CCLM best simulates the interannual variabilities of the percentile-based indices, while WRF shows better skill in reproducing their spatial patterns (TX10p, TX90p). In regard to the duration indices, RegCM4 outperforms WRF and CCLM in simulating the consecutive cold events (CSDI), while WRF performs best for the continuous hot days (WSDI). The humid heat wave, which is characterized by both high temperature and humidity, is skillfully reproduced by the RCMs as well. The overestimation of the magnitude and intensity of humid heat waves in WRF can be attributed to the favorable large-scale circulation and water vapor condition.

Mathematical modeling of heat and mass transfer processes of air masses in premises with an ice arena

BACKGROUND: The ventilation and air conditioning systems for ice arenas should not only provide a comfortable environment for the people indoors and on the ice but also protect the ice surface from moisture condensation. The use of finite element methods in designing the ventilation systems will make it possible to determine the temperature and humidity conditions in the entire volume of the ventilated room at the calculation stage and, if necessary, to correct the ventilation parameters at minimal costs at the design stage.&#x0D; AIM: To describe the methods of numerical simulation of heat and mass transfer in a room taking into account the humidity and radiant heat exchange for the case of a small training arena.&#x0D; MATERIALS AND METHODS: ANSYS CFX software was used for modeling, using the finite volume method for calculations. The object of the study was a digital twin of a small training ice arena, making it possible to take into account the thermal-physical processes occurring in the room. Analysis was performed for the steady-state (stationary) heat and mass transfer condition. The modeling results were evaluated by considering air temperature and humidity contours in the most characteristic secant planes. Given that the direct determination of air humidity was not possible using the software package, a description of a method for the determination of humidity by empirical equations was provided.&#x0D; RESULTS: It was numerically established that the air targets are met in the ice arena under the given parameters of operation of the ventilation system, with no moisture condensation on the surface of the ice, and comfortable conditions maintained in the areas where people are present.&#x0D; CONCLUSION: The modeling of the heat and mass exchange processes in the ice arena room makes it possible to avoid ice damage from moisture condensation as well as ensure the comfort of people present on the ice and in the bleachers.

Spatiotemporal variations on infrared temperature as a thermal comfort indicator for cattle under agroforestry systems.

With the expanding use of thermal assessment techniques in beef cattle, infrared thermography has become a promising tool for assessing the environment for animal thermal comfort. Goals of this study were: (1) to evaluate cattle thermal comfort in agroforestry systems with different shade availability (2) to verify the spatiotemporal variations of infrared temperature inside agroforestry systems, and; (3) to test infrared thermography as a potential tool to assess animal thermal comfort indices in agroforestry systems. A trial was carried out between June 2015 and February 2016, covering Central-Brazil's dry winter and rainy summer seasons, respectively. The experimental area of Embrapa Beef Cattle is located in Campo Grande (Mato Grosso do Sul), coordinates 20°24'53″ S, 54°42'26″ W and 558m altitude. The 12ha plot has two agroforestry systems varying shade availability. Traditional Black Globe Temperature and Humidity Index, Heat Load Index and Radiation Thermal Load were determined, from measurements using digital thermo-hygrometers, with datalogger. Surface temperature and humidity of tree canopies and pasture were determined using an infrared thermographic camera. Results show spatiotemporal variations in infrared temperature. This means that the environment inside agroforestry systems is not homogeneously comfortable for cattle, and the system with the lowest shade availability has the greatest heat accumulation area. Weak to strong associations were identified between infrared variables and thermal comfort indices (0.08=r≤0.75). Positive relationships were also obtained and equally well explained by the Black Globe Temperature and Humidity Index and Heat Load Index (0.55=R2≤0.94). We conclude that infrared thermography can be used as a tool to assess thermal comfort indices in agroforestry systems and to determine onset of animal thermal stress from environment and heat body accumulation.

Intensified Humid Heat Events Under Global Warming

AbstractBased on the Coupled Model Intercomparison Project Phase 5 multimodel simulations, this paper investigates the future changes in extreme wet‐bulb temperatures (TWs) and extreme dry‐bulb temperatures (Ts) globally under both low‐emission and high‐emission scenarios (Representative Concentration Pathways of 4.5 [RCP4.5] and 8.5 [RCP8.5]). Under a warming climate, T and TW exhibit a higher absolute increase in their mean values over the mid–high latitudes while they show higher relative increases in their mean values and variability over tropics. Humid and dry heat events which consist of consecutive extreme TWs and Ts show higher occurrences over tropics, governed by the joint increases in mean values and variability of TW and T therein. Humid heat events show intensifications to dry heat events with higher frequency, duration, and intensity, driven by the lower variability of TW than T. In the mid–high latitudes, heat events will start earlier and last longer in warm season under RCP8.5 than RCP4.5, motivating the need for global warming mitigation.

Heat and Humidity for Bioburden Reduction of N95 Filtering Facepiece Respirators.

Introduction: The coronavirus disease 2019 (COVID-19) pandemic has caused a global shortage of single-use N95 filtering facepiece respirators (FFRs). A combination of heat and humidity is a promising method for N95 FFR decontamination in crisis-capacity conditions; however, an understanding of its effect on viral inactivation and N95 respirator function is crucial to achieving effective decontamination. Objective: We reviewed the scientific literature on heat-based methods for decontamination of N95 FFRs contaminated with severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) and viral analogues. We identified key parameters for SARS-CoV-2 bioburden reduction while preserving N95 fit and filtration, as well as methods that are likely ineffective. Key Findings: Viral inactivation by humid heat is highly sensitive to temperature, humidity, duration of exposure, and the local microenvironment (e.g., dried saliva). A process that achieves temperatures of 70-85°C and relative humidity >50% for at least 30 min is likely to inactivate SARS-CoV-2 (>3-log reduction) on N95 respirators while maintaining fit and filtration efficiency for three to five cycles. Dry heat is significantly less effective. Microwave-generated steam is another promising approach, although less studied, whereas 121°C autoclave treatments may damage some N95 FFRs. Humid heat will not inactivate all microorganisms, so reprocessed N95 respirators should be reused only by the original user. Conclusions: Effective bioburden reduction on N95 FFRs during the COVID-19 pandemic requires inactivation of SARS-CoV-2 and preservation of N95 fit and filtration. The literature suggests that humid heat protocols can achieve effective bioburden reduction. Proper industrial hygiene, biosafety controls, and clear protocols are required to reduce the risks of N95 reprocessing and reuse.

Impact of elevated core temperature on cognition in hot environments within a military context.

PurposeCognition can be impaired during exercise in the heat, potentially contributing to military casualties. To our knowledge, the independent role of elevated core temperature during exercise has not been determined. The aim of the current study was to evaluate effects of elevated core temperature on cognition during physically encumbering, heated exercise, and to determine whether the perceptual cooling effects of menthol preserves cognition.MethodsEight participants complete three trials in randomised order: one normothermic (CON) and two with elevated (38.5°C) core temperature, induced by prior immersion in neutral versus hot water The CON trial and one hot trial (HOT) used a water mouth-rinse following each cognitive task of the trial, (HOT) while the other used a menthol mouth-rinse (MENT). Participants walked in humid heat (33°C, 75% relative humidity) in military clothing, completing a cognitive battery of reaction time, perceptual processing, working memory, executive function, cognitive flexibility, vigilance, and declarative memory.ResultsNo differences in cognitive performance were observed between any conditions. Near-infrared spectroscopy showed greater oxygenated haemoglobin tissue content in HOT and MENT compared to CON (ΔO2Hb-deO2Hb: 2.3 ± 4.5 µM, p < .024), and lower deoxygenated haemoglobin in MENT than in CON or HOT (p = .017), suggesting higher brain metabolism during the more stressful conditions.ConclusionModerately elevated core (38.5°C) and skin temperature does not appear to impair cognitive performance during exercise despite mildly elevated cerebral metabolism. The effects of menthol remain undetermined due to the lack of heat-mediated cognitive impairment.

Estimation of heat exchanges in Boer crossbred goats maintained in a climate chamber.

Exposure of goats to high air temperatures can induce physiological and behavioral adjustments, increasing the dissipation of excess body heat in the latent form, and intensification of the use of these thermoregulatory tools can result in physiological and productive damage to animals. With this, the objective of the research was to quantify the levels of thermal stress and the sensible and latent heat losses of Boer crossbred goats submitted to different air temperatures, in a climatic chamber. Six male crossbred goats of the Boer breed, with an average weight of 25.06±4.43kg and mean age of six months, were grouped using a completely randomized design, with three treatments (air temperatures of the 26, 30 and 34°C, respectively) and six replicates (animals) with 68% relative humidity. The temperature and relative humidity of the air were collected to calculate the temperature and humidity index (THI) and heat exchanges. Were collected the physiological responses rectal temperature (RT) and surface (ST) and respiratory rate (RF), with these data were estimated the heat exchanges by radiation (L), convection (Cr), total sensitive (Gs), latent of the respiratory tract (Er), cutaneous (Ec), total latent (Et) and total heat exchange (Wt). It was found that the THI values were classified as thermal comfort, moderate stress and very stressful, respectively, in the three conditions evaluated. With the increase in AT, the animals significantly increased (P<0.05) the RT, ST and RF, and consequently reduced sensitive heat exchanges, from 38 to 8%, and increased latent heat exchanges, from 62 to 92%, when compared air temperatures of 26 and 34°C, respectively. Physiological responses showed a significant negative (P<0.05) correlation with sensitive heat exchanges and a positive correlation with latent heat exchanges. In very stressful thermal conditions, the animals lost almost all of the excess metabolic heat by latent means (skin and respiratory tract).

Prospects of application of electrotechnological methods in silkworm growing

This article shows the possibilities of increasing the resistance of the silkworm to various diseases, the amount of silkworm production using an air aeration device when growing the silkworm. High humidity and strong gas heat in the wormhole have a negative impact on the life of the worms. It causes additional diseases. Therefore, depending on the outside air temperature every two hours, it is necessary to open the doors and windows and ventilate for 15-30 minutes.

Research on the influence of humid heat environment on the mechanical properties of multilayer composite structure

For resin-based composite materials, the hot and humid environment has a very obvious impact on its performance. Moisture can penetrate into the composite material through diffusion and capillary action, which causes the resin matrix with plasticization, swelling and hydrolysis, and swelling and infiltration of liquid will lead to micro-stress inside the material. Thus, the polymer macromolecular chain will stretche or even break, and it can lead to the weakening of the interface properties of the resin and the fiber, which in turn leads to fluctuations in the mechanical properties of the composite material. In this paper, we carried out damp and heat tests on multilayer composite structures to study the effects of different temperature and humidity environments on the physical and chemical properties and mechanical properties of composite materials. The law of moisture absorption characteristics of composite materials is clarified, and the moisture absorption in the initial stage of moisture absorption is proportional to the moisture absorption time t1/2. With time increasing, the moisture absorption gradually tends to balance, and the higher are the damp and heat conditions, the greater the moisture absorption of the composite material will be. The moisture absorption is between 0.13% and 0.78% with different damp and heat environments. The chemical structure of the composite material itself has not changed significantly, and the damp-heat effect will induce the destruction of the fiber-matrix interface and the expansion of cracks along the pores, which weakens the bonding strength of the interface. As a result, the moisture makes the transverse performance and shear performance of the composite material greatly reducing, but has little effect on the longitudinal performance.

The Effect of 2 Humidifier Temperature Settings on Inspired Gas Temperatures and the Physiological Parameters of Preterm Infants Receiving Mechanical Ventilation Therapy.

The use of heated and humidified gas during mechanical ventilation is routine care in neonatal intensive care units. Giving gas at inadequate heat and humidity levels can affect neonatal morbidity and mortality. To compare the effects of 2 humidifier temperature settings on the temperature and humidity of the inspired gas and the physiologic parameters in preterm newborns receiving mechanical ventilation. The research was conducted in a single-group quasi-experimental design. Proximal temperature was measured using a humidity heat transmitter. The humidifier temperature was set at 38°C (temperature I) and then at 39°C (temperature II). The mean proximal temperatures were significantly lower than the values set in the humidifier (33.8 ± 1.20°C at temperature I, and 34.06 ± 1.30°C at temperature II, P < .001). However, the difference between the 2 proximal temperatures was not significant (P = .162). The incubator temperature was found to be effective on the proximal gas temperature (P < .05). It was found that only preterm infants in the temperature II group had a higher mean heart rate (P < .05). Incubator temperatures may have an effect on inspired gas temperature in preterm infants who are mechanically ventilated and caregivers should be aware of these potentially negative effects. Future studies should focus on how to measure the temperature and humidity of gas reaching infants in order to prevent heat and humidity losses.

Moist heat stress extremes in India enhanced by irrigation

Intensive irrigation in India has been demonstrated to decrease surface temperature, but the influence of irrigation on humidity and extreme moist heat stress is not well understood. Here we analysed a combination of in situ and satellite-based datasets and conducted meteorological model simulations to show that irrigation modulates extreme moist heat. We found that intensive irrigation in the region cools the land surface by 1 °C and the air by 0.5 °C. However, the decreased sensible heat flux due to irrigation reduces the planetary boundary layer height, which increases low-level moist enthalpy. Thus, irrigation increases the specific and relative humidity, which raises the moist heat stress metrics. Intense irrigation over the region results in increased moist heat stress in India, Pakistan, and parts of Afghanistan—affecting about 37–46 million people in South Asia—despite a cooler land surface. We suggest that heat stress projections in India and other regions dominated by semi-arid and monsoon climates that do not include the role of irrigation overestimate the benefits of irrigation on dry heat stress and underestimate the risks. Intensive irrigation in India cools the land surface, but increases the moist heat stress in South Asia, according to an analysis of observational datasets and meteorological models.

NICU Collaboration During the COVID-19 Worldwide Pandemic: A Memory of Gratitude.

NICU Collaboration During the COVID-19 Worldwide Pandemic: A Memory of Gratitude.

Oil protects bacteria from humid heat in thermal processing

High-fat low-moisture foods are often implicated in outbreaks of Salmonellosis. Research has suggested that the fat content in peanut butter may play an important role in protecting Salmonella from thermal inactivation. Our recent studies indicate that the water activity (aw) of oil reduces sharply with increasing temperature, which causes desiccation to the bacteria and consequently enhances their thermal resistance. Therefore, a humid heating environment may help accelerate the thermal inactivation rate of bacteria inside oil. In this research, we selected Enterococcus faecium NRRL B-2354 (E. faecium) as a surrogate of Salmonella to study how the bacterium inside oil responds to thermal treatments under different relative humidities (RHs). Specially, we determined the decimal reduction time (D-value) of E. faecium in peanut oil which was exposed to different RHs (0–100%) at 80 °C. The data revealed that the D80 of E. faecium in 0.51 mm oil layers reduced exponentially from 6335.8 to 9.6 min with increasing RH (0–61%), then stayed constant (7.7 ± 1.5 min) at higher RH levels (61–100%). Further experiments with reduced sample thicknesses (0.26 & 0.10 mm) revealed significantly lower D80 values in thinner oil layers than in thicker oil layers at those high RH levels (61%–100%). The results of this study indicate that the water vapor equilibration was not reached in oil in short-time high-RH thermal treatments. This study suggests that oil protects bacteria from thermal inactivation not only through desiccation of bacterial cells but also by serving as a moisture barrier to hinder environmental water vapor from rehydrating the bacteria during short-time high-RH thermal processing.