Ambient Heating for Heat Stress

Overseen By Taysom Wallace, MS

Age: 18+

Sex: Any

Trial Phase: Academic

Sponsor: University of Texas Southwestern Medical Center

Must not be taking: Beta blockers, Calcium channel blockers

Disqualifiers: Heart disease, Cancer, Diabetes, others

No Placebo Group All trial participants will receive the active study treatment (no placebo)

Compensation: Varies

Number of Visits: 1

What You Need to Know Before You Apply

What is the purpose of this trial?

This trial aims to understand how skin temperatures respond to heat with and without cooling methods like fans or sweat. Researchers use various tools to measure temperature, comparing readings from the skin surface and just below it. The study involves ambient heating (also known as environmental or room temperature heating) to create heat stress conditions. Individuals with no significant health problems and a normal heart test might be suitable participants. As an unphased study, this trial offers a unique opportunity to contribute to scientific understanding of temperature regulation and cooling methods.

Will I have to stop taking my current medications?

Yes, if you are taking medications that affect how your body handles heat, like certain heart medications, you would need to stop taking them to participate in this trial.

What prior data suggests that ambient heating is safe for skin temperature studies?

Research shows that hot environments can seriously affect health. Heat stress can lead to problems like heat exhaustion and heat stroke, and it can worsen conditions such as heart disease and diabetes.

People working in hot places sometimes suffer injuries or even death. Studies indicate that most heat-related deaths occur in the first few days of working in the heat, before the body acclimates. People need time to adjust to high temperatures.

While heat can be dangerous, managing exposure carefully and gradually can lower the risks. Always watch for signs of heat-related illness, such as dizziness or nausea, and take steps to cool down if needed. ^{1 2 3 4 5}

Why are researchers excited about this trial?

Researchers are excited about the Ambient Heating for Heat Stress trial because it explores innovative ways to manage body temperature in stressful heat conditions. Unlike conventional methods that often rely on external cooling devices, this trial investigates the use of ambient heating to better understand how the body regulates temperature. The study compares different methods of measuring skin temperature, such as skin surface thermistors and intradermal needles, to provide more accurate and responsive data. By improving our understanding of heat stress management, this trial could lead to more effective strategies to prevent heat-related illnesses.

What evidence suggests that ambient heating is effective for managing heat stress?

Research has shown that heat stress poses a serious health risk, linked to increased mortality and worsening conditions like heart disease and diabetes. This trial will explore ambient heating, a method that adjusts the surrounding temperature to help the body manage heat stress more effectively. By modifying the ambient temperature, this approach may enhance the body's natural cooling ability without medication. Studies have found that effectively managing heat stress can lower health risks, especially in hot weather. This method focuses on helping the body regulate its temperature, potentially reducing the dangers of extreme heat. Participants in this trial will be assigned to different treatment arms to evaluate the effectiveness of various temperature monitoring techniques, such as the Skin Temperature Thermistor on the skin surface, the Intradermal Skin Temperature Needle on the skin surface, and the Intradermal Skin Temperature Needle in the intradermal skin layer. ^{1 4 6 7 8}

Who Is on the Research Team?

Craig Crandall, Ph.D.

Principal Investigator

UT Southwestern Medical Center

Are You a Good Fit for This Trial?

This trial is for healthy individuals without significant medical issues, as determined by a detailed medical history and physical exam. Participants must have a normal resting electrocardiogram. It's not suitable for those with underlying health problems that could affect their response to heat stress.

Inclusion Criteria

Free of any significant underlying medical problems based upon a detailed medical history and physical exam

Normal resting electrocardiogram

Exclusion Criteria

I am a current smoker or have smoked regularly in the last 3 years.

Individuals who are pregnant, planning to become pregnant, or breastfeeding

I have a chronic condition like heart disease, diabetes, or high blood pressure that needs regular treatment.

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

1-2 weeks

Heat Stress Exposure

Participants are exposed to ambient heat stress with and without evaporative and convective cooling methods. Skin surface and intradermal temperatures are monitored.

2 hours

1 visit (in-person)

Follow-up

Participants are monitored for any delayed thermoregulatory responses or adverse effects after the heat stress exposure.

1 week

What Are the Treatments Tested in This Trial?

Interventions

• Ambient Heating

Trial Overview The study aims to observe how skin surface and deeper skin temperatures react to being heated up in different conditions—with and without the help of sweat (evaporative cooling) and air movement (convective cooling).

How Is the Trial Designed?

Group I: Skin Temperature Thermistor on Skin Surface Active Control 4 Interventions

Group II: Intradermal Skin Temperature Needle on Skin Surface Active Control 4 Interventions

Group III: Intradermal Skin Temperature Needle in Intradermal Skin Layer Active Control 4 Interventions

Who Is Running the Clinical Trial?

University of Texas Southwestern Medical Center

Lead Sponsor

Trials

1,102

Recruited

1,077,000+

Published Research Related to This Trial

The Effective Heat Strain Index (EHSI) is a practical tool that allows for on-site evaluation of heat stress conditions by using a hand calculator that incorporates temperature measurements and estimates of metabolism and air movement.

The EHSI provides clear classifications of heat strain levels (no strain, low strain, high strain) and suggests time limits for safe exposure, helping to ensure safety in hot environments.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Effective heat strain index using pocket computer. Kamon, E., Ryan, C.[2008]

Indoor temperature showed little variation across different seasons and locations, while indoor relative humidity varied significantly, indicating that indoor conditions do not always reflect outdoor measurements.

The study suggests that outdoor measurements of specific humidity are more reliable indicators of indoor moisture content than outdoor temperature and relative humidity, which is important for understanding health effects related to weather.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Daily indoor-to-outdoor temperature and humidity relationships: a sample across seasons and diverse climatic regions. Nguyen, JL., Dockery, DW.[2018]

Thermal stress from extreme cold and heat can significantly impact health and productivity, with risks increasing in harsh environmental conditions and high workloads.

The body undergoes physiological changes to adapt to thermal stress, and understanding these adaptations is crucial for preventing heat and cold-related illnesses and implementing effective therapies.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Environmental thermal stress. Keim, SM., Guisto, JA., Sullivan, JB.[2008]

In a study of 179 workers in the Monsoonal North region of Australia, 79% reported chronic heat stress symptoms and 47% reported severe symptoms, indicating a high prevalence of heat-related health issues in labor-intensive jobs.

Exposure to air-conditioning significantly reduced the likelihood of both chronic and severe heat stress symptoms, suggesting that implementing cooling strategies could effectively mitigate the negative impacts of heat exposure on workers.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

The impact of perceived heat stress symptoms on work-related tasks and social factors: A cross-sectional survey of Australia's Monsoonal North. Carter, S., Field, E., Oppermann, E., et al.[2021]

The report develops a comprehensive theory on how the human body exchanges heat with the environment, focusing on factors like metabolic heat production during physical activity and the mechanisms of heat elimination through conduction, convection, evaporation, and radiation.

It also discusses various indices for measuring thermal comfort and stress, including the Fanger equations, which help assess wellbeing and discomfort related to temperature changes.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

[Heat exchange between human body and environment (theoretical bases of physiological measurement and evaluation)]. Pezzagno, G.[2008]

Understanding the physiological and psychological impacts of working in extreme conditions is crucial for preventing excessive strain, as factors like physical fitness, age, and sex influence an individual's maximal aerobic capacity.

The study highlights the importance of heat balance during work, emphasizing that metabolic heat production and heat exchange methods (radiation, convection, and evaporation) significantly affect physiological responses and mental performance under heat stress.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Ergonomics of heat and cold. Kamon, E.[2017]

The body's natural response to heat stress, such as increased blood flow to the skin and sweating, can lead to significant health risks, especially in vulnerable populations like the elderly, as these responses can overload the heart and increase the risk of serious conditions like thrombosis.

Current safety guidelines for radiofrequency (RF) radiation exposure are considered trivial compared to the body's heat stress responses, but prolonged exposure to RF levels above recommended limits may pose health risks, highlighting the need for careful monitoring of heat stress in various environments.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Cardiovascular responses to heat stress and their adverse consequences in healthy and vulnerable human populations. Donaldson, GC., Keatinge, WR., Saunders, RD.[2022]

A meta-analysis of studies indicates that higher heat exposure is linked to an increase in occupational injuries, particularly affecting younger workers and males, with a reported 0.5% increase in injury odds for every 1°C rise in temperature.

While the exact mechanisms behind heat exposure leading to injuries are still being explored, effective prevention strategies have yet to be established, highlighting the need for tailored approaches that consider local conditions and involve community participation.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Heat Exposure and Occupational Injuries: Review of the Literature and Implications. Spector, JT., Masuda, YJ., Wolff, NH., et al.[2023]

In a study of 46 industrial workers exposed to varying heat stress levels, heart rates and rectal temperatures were monitored, revealing that safety levels (HR ≤ 110 bpm, Tre ≤ 38.0 °C) were maintained in only 2.4% of cases at higher work rates during winter, indicating significant risks under these conditions.

Workers acclimatized to hot environments experienced fewer instances of excessive heart rates and temperatures, suggesting that acclimatization plays a crucial role in enhancing safety and performance in heat-stressed conditions.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Laboratory evaluation of permissible exposure limits for men in hot environments. Kuhlemeier, KV., Wood, TB.[2008]

Thermal stress in work environments can adversely impact human performance and behavior, highlighting the importance of understanding these effects for workplace safety.

The review indicates that variations in research methodology and definitions of thermal stress complicate the evaluation of its effects, suggesting a need for standardized approaches in future studies.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Thermal stress and human performance. Enander, AE., Hygge, S.[2019]

Passive heat therapy, such as using hot tubs or saunas, can enhance the body's resistance to oxidative and inflammatory stress, which is beneficial for cardiovascular health, as shown in a study using human endothelial cells.

Both mild heat exposure (at 39°C) and serum from individuals who underwent 8 weeks of heat therapy were effective in preventing cellular damage from hypoxia-reoxygenation, suggesting that heat therapy may offer protective mechanisms against ischemic events.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

Passive heat therapy protects against endothelial cell hypoxia-reoxygenation via effects of elevations in temperature and circulating factors. Brunt, VE., Wiedenfeld-Needham, K., Comrada, LN., et al.[2019]

The study found that increased indoor heat exposure is associated with higher mortality and morbidity rates among the elderly in Houston, Texas, with a notable odds ratio of 1.16 for circulatory deaths per 5°C increase in indoor temperature.

Stronger associations were observed between indoor heat and emergency hospital admissions among African Americans compared to Whites, highlighting the need to consider demographic vulnerabilities when assessing health risks related to indoor heat exposure.

NCBI (Pubmed)

pubmed.ncbi.nlm.nih.gov

A Case-Crossover Analysis of Indoor Heat Exposure on Mortality and Hospitalizations among the Elderly in Houston, Texas. O'Lenick, CR., Baniassadi, A., Michael, R., et al.[2021]

Citations

1. who.int who.int/news-room/fact-sheets/detail/climate-change-heat-and-health

Heat and health Heat stress is the leading cause of weather-related deaths and can exacerbate underlying illnesses including cardiovascular disease, diabetes, ...

2. thelancet.com thelancet.com/journals/lancet/article/PIIS0140-6736(21)01208-3/fulltext

Hot weather and heat extremes: health risks Hot ambient conditions and associated heat stress can increase mortality and morbidity, as well as increase adverse pregnancy outcomes and ...

3. sciencedirect.com sciencedirect.com/science/article/abs/pii/S2212095520303758

The effects of climatic and environmental factors on heat ... This study aimed to identify climatic and environmental factors influencing the occurrence of heatstroke.

4. ehp.niehs.nih.gov ehp.niehs.nih.gov/EHP11807

Humidity's Role in Heat-Related Health Outcomes On physiological and biophysical grounds, exposure to higher levels of humidity should worsen heat stress by decreasing sweat evaporation.

5. withpower.com withpower.com/trial/ambient-heating-for-heat-stress-d0b17

Ambient Heating for Heat Stress · Info for Participants Ambient Heating is unique because it involves adjusting the environment's temperature to help the body manage heat stress, rather than using medications or ...

6. osha.gov osha.gov/heat-exposure

Overview: Working in Outdoor and Indoor Heat Environments Most outdoor fatalities, 50% to 70%, occur in the first few days of working in warm or hot environments because the body needs to build a tolerance to the heat ...

7. cdc.gov cdc.gov/niosh/docs/2016-106/pdfs/2016-106.pdf

Occupational Exposure to Heat and Hot Environments Occupational exposure to heat can result in injuries, disease, reduced productivity, and death. To address this hazard, the National Institute for Occupational ...

8. pmc.ncbi.nlm.nih.gov pmc.ncbi.nlm.nih.gov/articles/PMC10475595/

Study on thermal health and its safety management mode for ... This study proposes three key elements of thermal health in the working environment, namely thermal health states, absence of heat-related illnesses, and heat ...