Physiological Strain in Young Adults During a Simulated Heat Wave

University of Ottawa

Status: Completed

Conditions: Physiological Stress; Heat Stress

Treatments: Other: Simulated indoor overheating exposure

Study type: Interventional

Funder types: Other

Identifiers

NCT06618352

HEPRU-2024-09-C

Details and patient eligibility

About

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.

Enrollment: 20 patients

Sex: All

Ages: 18 to 35 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• Non-smoking.
• English or French speaking.
• Ability to provide informed consent.

Exclusion criteria

• Chronic health conditions.
• Endurance trained
• Regular exposure to heat (e.g., hot baths, sauna, regular exercise in the heat, recent vacation to area with high temperature).

Trial design

Primary purpose: Basic Science

Allocation: N/A

Interventional model: Single Group Assignment

Masking: None (Open label)

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20 participants in 1 patient group

Daylong exposure to extreme heat

Experimental group

Description:

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.

Treatment:

Other: Simulated indoor overheating exposure