Suitability of a 26 °C Indoor Environment for Mitigating Heat Strain in Young Adults
Recruiting now · Not applicable
Conditions studied: Heat Stress, Physiological Stress, Cognitive Change
In brief
While an indoor upper temperature limit of 26 °C has been shown to protect heat-vulnerable older adults (DOI: 10.1289/EHP11651), this guideline has not been verified in young, habitually active adults. Public health recommendations during hot weather typically emphasize staying in cool environments, avoiding strenuous activity, wearing lightweight clothing, and maintaining adequate hydration. However, young adults may be less likely to follow these guidelines. They often do not reduce their physical activity during extreme heat events and may overdress for fashion, cultural, or religious reasons. These behaviors can impose an additional thermoregulatory burden and lead to greater physiological strain during heat exposure, even though young adults generally have a higher capacity for heat dissipation than older individuals. Accordingly, it is important to evaluate whether an indoor temperature limit of 26 °C is sufficient to protect young, habitually active adults. To address this gap, the investigators aim to assess changes in body temperature and cardiovascular strain in young, habitually active adults (18-29 years) during an 8-hour exposure to the recommended indoor upper temperature limit of 26 °C and 45% relative humidity (humidex of 29, considered comfortable). Participants will complete two conditions: A) seated rest while dressed in light clothing (T-shirt, shorts, and socks), and B) light exercise (stepping to simulate activities of daily living, 4-4.5 METs) performed once per hour (except for the lunch hour) while dressed in light clothing plus an additional insulating layer (sweatshirt and sweatpants). This experimental design will allow investigators to determine the effects of added clothing insulation and light activity-representative of typical daily behaviors-on physiological strain in young adults, and to assess whether refinements to the recommended 26 °C indoor temperature limit are warranted for this population.
Key facts
- Study ID
- NCT07267598
- Run by
- University of Ottawa
- People needed
- 10
- Starts
- 2025-11-07
- Expected to finish
- 2026-12-30
- Last updated by the study team
- 2026-06-16
Who can join
Age: 18 and older, up to 29. Sex: any. Healthy volunteers: not accepted.
You may qualify if…
- Non-smoking.
- English or French speaking.
- Ability to provide informed consent.
- Healthy young adults without chronic disease (e.g., type 1 diabetes, hypertension)
You may not qualify if…
- Endurance trained (i.e., engaged in regular physical training activities more than 3 times a week for more than 1 hour per session).
- Undergoing passive heat exposures such as regular of saunas, warm-water immersion, other.
- Use of or changes in medication judged by the patient or investigators to make participation in this study inadvisable.
- Current pregnancy
Where it is running
- University of Ottawa — Ottawa, Ontario, Canada (enrolling)
Full record on ClinicalTrials.gov
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