10 Participants Needed

Simulated Heat Exposure for Heat Stress

GP
Overseen ByGlen P Kenny, PhD
Age: 18 - 65
Sex: Any
Trial Phase: Academic
Sponsor: University of Ottawa
No Placebo GroupAll trial participants will receive the active study treatment (no placebo)
Approved in 2 JurisdictionsThis treatment is already approved in other countries

Trial Summary

What is the purpose of this trial?

The likelihood of exposure to overheated indoor environments is increasing as climate change is exacerbating the frequency and severity of hot weather and extreme heat events. Prolonged exposure to excessive heat stress can result in a deterioration in physiological function leading to a myriad of pathophysiological conditions (e.g., heat exhaustion, acute kidney injury, adverse cardiovascular events, heat stroke) that if left untreated can lead to death. While the relationship between extreme heat events and human health has been assessed in relation to outdoor exposure to high heat conditions, relatively little is known about the effects of daylong exposures to indoor overheating on the body's physiology. In this study, investigators will examine the change in physiological responses (i.e., thermal, cardiovascular) in young (18-35 years) adults exposed to successive days and nights of high indoor temperatures typical of conditions recording in dwellings without air conditioning during the 2021 Western Heat Dome. Specifically, study participants will be housed in a large environmental chamber (outfitted with bed, work space, sitting area, kitchen and bathroom) for three successive days (three days and two nights) while exposed to indoor overheating where daytime temperatures will be maintained at 36°C (45% relative humidity; note: 36°C, temperatures experienced in homes without air-conditioning) for a 10-hour daytime exposure period (DAYTIME: defined as the time period from 9:00 to 19:00). For the nighttime exposure period (NIGHTTIME: defined as the time period from 19:00 to 9:00), participants will be exposed to nighttime temperatures fixed at 31°C (45% relative humidity; note: reductions in indoor temperatures during the nighttime in large urban centers range between 4-6°C). Participants will be permitted to move freely throughout the day in the chamber, but will be restricted from performing any physical activity except for the completion of a battery of tests (cardiovascular, cognitive and posture assessments performed prior to (as performed between 7:00 and 9:00) and the end (as performed between 17:00 and 19:00) of the daytime exposure). During the nighttime period, participants will be permitted to move freely until they decide to go to bed.

Will I have to stop taking my current medications?

The trial protocol does not specify whether you need to stop taking your current medications. However, since the trial excludes people with chronic health conditions, it might imply that participants should not be on regular medication for such conditions.

Is simulated heat exposure generally safe for humans?

The PSU HEAT protocol, used to study heat stress, has been shown to be reliable and valid for determining safe environmental limits for humans, but specific safety data for simulated heat exposure in clinical trials is not provided in the available research.12345

Research Team

GP

Glen P Kenny, PhD

Principal Investigator

University of Ottawa

Eligibility Criteria

This trial is for young adults aged 18-35 who speak English or French, do not smoke, and can give informed consent. It's designed to study the effects of heat waves on people in indoor settings without air conditioning.

Inclusion Criteria

I do not smoke.
I can understand and agree to the study's procedures and risks.

Timeline

Screening

Participants are screened for eligibility to participate in the trial

1-2 weeks

Exposure

Participants are exposed to high indoor temperatures in an environmental chamber for three successive days and two nights, with specific daytime and nighttime temperature settings.

3 days
Continuous exposure in the chamber

Assessment

Participants undergo cardiovascular, cognitive, and postural assessments during the exposure period.

3 days
Assessments conducted twice daily

Follow-up

Participants are monitored for any delayed physiological effects after the exposure period.

1 week

Treatment Details

Interventions

  • Simulated indoor overheating exposure
Trial Overview Participants will be exposed to high temperatures inside an environmental chamber simulating a heat wave. They'll experience daytime temps of 36°C and nighttime temps of 31°C over three days while their physiological responses are monitored.
Participant Groups
1Treatment groups
Experimental Treatment
Group I: Daylong exposure to extreme heatExperimental Treatment1 Intervention
Young adults exposed to daylong indoor overheating associated with an extreme heat event involving a 10-hour daytime exposure at 36°C (45% relative humidity) followed by a 14-hour nighttime exposure at 31°C (45% relative humidity) over three successive days with only a daytime exposure on the final day.

Simulated indoor overheating exposure is already approved in European Union, United States for the following indications:

🇪🇺
Approved in European Union as Lynparza for:
  • Breast cancer
  • Ovarian cancer
  • Fallopian tube cancer
  • Peritoneal cancer
  • Pancreatic cancer
  • Prostate cancer
🇺🇸
Approved in United States as Lynparza for:
  • Ovarian, fallopian tube, and primary peritoneal cancer
  • Breast cancer
  • Prostate cancer
  • Pancreatic cancer

Find a Clinic Near You

Who Is Running the Clinical Trial?

University of Ottawa

Lead Sponsor

Trials
231
Recruited
267,000+

Findings from Research

The PSU HEAT protocol shows excellent reliability and validity for determining critical environmental limits, with a high intraclass correlation coefficient (ICC) of 0.98 for between-visit reliability among 12 subjects.
The protocol effectively identifies critical temperature and humidity thresholds for heat stress, with strong agreement in results across different trials, indicating it can be reliably used to assess human heat balance.
Validity and reliability of a protocol to establish human critical environmental limits (PSU HEAT Project).Cottle, RM., Wolf, ST., Lichter, ZS., et al.[2023]
A study of 31,642 heat stress illness cases among active duty servicemembers from 1998 to 2019 found that higher daily heat indices, particularly maximum wet bulb globe temperature (WBGT) and heat index, significantly increase the risk of heat-related illnesses, with risks nearly doubling at higher temperatures.
The research suggests that prevention strategies should consider previous day's heat levels and monitor various heat indices, not just WBGT, to better assess risks and implement effective control measures for heat stress illnesses.
Heat stress morbidity among US military personnel: Daily exposure and lagged response (1998-2019).Lewandowski, SA., Shaman, JL.[2022]
In a study involving 252 laboratory rats, it was found that running to exhaustion at various temperatures led to a higher risk of mortality from hyperthermia compared to being restrained and heated, with LD25 values of 16.8 and 30.1 degree-minutes, respectively.
The research indicates that both the severity of core heating and the physical effort involved can predict mortality rates, suggesting that exercise increases the risk of heatstroke even at lower temperatures.
Rat model of acute heatstroke mortality.Hubbard, RW., Bowers, WD., Matthew, WT., et al.[2017]

References

Validity and reliability of a protocol to establish human critical environmental limits (PSU HEAT Project). [2023]
Heat stress morbidity among US military personnel: Daily exposure and lagged response (1998-2019). [2022]
Rat model of acute heatstroke mortality. [2017]
Novel metrics for relating personal heat exposure to social risk factors and outdoor ambient temperature. [2021]
Actual and simulated weather data to evaluate wet bulb globe temperature and heat index as alerts for occupational heat-related illness. [2020]
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