10 Participants Needed

Simulated Indoor Overheating for Heat Stress

GP
Overseen ByGlen P Kenny, PhD
Age: 18+
Sex: Any
Trial Phase: Academic
Sponsor: University of Ottawa
No Placebo GroupAll trial participants will receive the active study treatment (no placebo)

What You Need to Know Before You Apply

What is the purpose of this trial?

Laboratory-based studies show that exposure to high humidity can worsen the effects of heat stress in young and older adults by impeding sweat evaporation - the main mechanism by which the human body cools itself. At high levels of humidity, the efficiency of sweating decreases causing a greater rise core temperature and burden on the cardiovascular system. In this context, increasing temperatures and humidity with climate change thus pose a potential compound risk for human health. While humidity's role in heat-health outcomes could substantially alter projections of health burdens from climate change, the impact of humidity on physiological strain in vulnerable people in relation to the indoor environment has yet to be evaluated. In a recent study delineating the physiological effects of the proposed 26°C indoor upper limit (PMID: 38329752), relative humidity was set to 45% in all conditions based on indoor humidity standards by the American Society of Heating and Air-Conditioning Engineers. However, it is unknown whether a refinement of the recommended indoor temperature limit of 26°C is required in situations where humidity cannot be maintained at this level.On separate occasions, the investigators will assess the change in body temperature and cardiovascular strain in older adults (65-85 years) exposed for 10 hours at the recommended indoor temperature limit of 26°C and 45% relative humidity (equivalent humidex of 29 (considered comfortable)) (experimental condition A), to 26°C with a relative humidity of 15% (equivalent humidex of 23 (considered comfortable); humidex is used to measure the perceived temperature taking into account the humidity)) (experimental condition B), to 26°C with a relative humidity of 85% (equivalent humidex of 37 (considered somewhat uncomfortable)) (experimental condition C), and to 31°C and 45% relative humidity with an equivalent humidex of 37 (considered somewhat uncomfortable) that is similar to experimental condition C. With this experimental design, investigators will assess the effects of indoor humidity in driving human heat strain and identify whether refinements in the recommended 26°C indoor temperature limit may be required. Further, by evaluating changes in relation to ambient conditions with a similar humidex, the investigators can assess how individuals perceive and respond to both heat and humidity.

Are You a Good Fit for This Trial?

This trial is for non-smoking older adults aged 65-85 who can communicate in English or French and give informed consent. It includes those with chronic hypertension or type 2 diabetes diagnosed at least 5 years ago.

Inclusion Criteria

I do not smoke.
I speak English or French.
I can understand and agree to the study's procedures and risks.
See 1 more

Timeline for a Trial Participant

Screening

Participants are screened for eligibility to participate in the trial

2-4 weeks

Experimental Exposure

Participants are exposed to different indoor temperature and humidity conditions to assess physiological responses.

10 hours per session
4 sessions (in-person)

Follow-up

Participants are monitored for safety and effectiveness after exposure sessions

4 weeks

What Are the Treatments Tested in This Trial?

Interventions

  • Simulated indoor overheating
Trial Overview The study tests how different levels of indoor humidity affect body temperature and heart strain during a simulated heat wave. Participants will experience varying conditions, including the recommended limit of 26°C at different humidities.
How Is the Trial Designed?
4Treatment groups
Experimental Treatment
Group I: Exposure to recommended indoor temperature limit with normal indoor humidityExperimental Treatment1 Intervention
Participants exposed daylong (10 hours) to an indoor temperature maintained at 26°C and 45% relative humidity (humidex equivalent of 29).
Group II: Exposure to recommended indoor temperature limit with low indoor humidityExperimental Treatment1 Intervention
Participants exposed daylong (10 hours) to an indoor temperature maintained at 26°C and 15% relative humidity (humidex equivalent of 23).
Group III: Exposure to recommended indoor temperature limit with high indoor humidityExperimental Treatment1 Intervention
Participants exposed daylong (10 hours) to an indoor temperature maintained at 26°C and 85% relative humidity (humidex equivalent of 37).
Group IV: Exposure to high indoor temperature with normal indoor humidityExperimental Treatment1 Intervention
Participants exposed daylong (10 hours) to an indoor temperature maintained at 31°C and 45% relative humidity (humidex equivalent of 37).

Find a Clinic Near You

Who Is Running the Clinical Trial?

University of Ottawa

Lead Sponsor

Trials
231
Recruited
267,000+
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