Suitability of the 26 °C Indoor Temperature Upper Limit for Older Adults: Impacts of Clothing and Daily Activity
Trial statusRecruiting
Trial phaseNot applicable
Trial typeInterventional
Biological sexAll
Age65-85
SponsorUniversity of Ottawa
About this trial
While an upper limit of 26°C has been shown to be protective for heat-vulnerable older occupants (DOI: 10.1289/EHP11651), this recommendation did not consider the added heat burden associated with increases in internal heat production accompanying activities of daily living or the restriction to heat loss caused by clothing insulation. To safeguard the health of older adults, health agencies worldwide recommend the remain in cool space indoors, avoid strenuous activity, wear lightweight clothing, and drink cool water regularly throughout the day. However, older adults do not sense heat as well as their younger counterparts. Consequently, they may not take appropriate countermeasures to mitigate physiological strain from indoor overheating. This may include overdressing despite high indoor temperatures. In other cases, individuals may wear insulated clothing in hot weather to observe cultural or religious modesty requirements, which serve as expressions of faith and identity rather than a tool for thermoregulation. Further, individuals may be unaware of the consequences of increases in physical activity on heat gain and may therefore not adjust their normal day-to-day activity levels to prevent potentially dangerous rises in body temperature. Consequently, this may necessitate a lowering of recommended upper indoor temperature limit during hot weather.
To address these important considerations, on separate occasions the investigators will assess the change in body temperature and cardiovascular strain in older adults (65-85 years) exposed for 8 hours to the recommended indoor temperature upper limit of 26°C and 45% relative humidity equivalent humidex of 29 (considered comfortable) while they A) perform seated rest dressed in light clothing (t-shirt, shorts and socks), B) perform light exercise (stepping exercise to simulate activities of daily living, 4-4.5 METS) every hour (except during lunch hour period) dressed in light clothing, C) perform light exercise (4-4.5 METS) every hour (except during lunch hour period) dressed in light clothing (t-shirt, shorts and socks) and an added clothing layer (sweatshirt and sweatpants) and D) perform seated rest dressed in light clothing (t-shirt, shorts and socks) and an added clothing layer (sweatshirt and sweatpants). With this experimental design, investigators will assess the effects of added clothing insulation and light activity, representative in activities of daily living on physiological strain and identify whether refinements in the recommended 26°C indoor temperature limit may be required.
Eligibility criteria
This trial accepts healthy volunteersQualifiers
Non-smoking.
English or French speaking.
Ability to provide informed consent.
with or without a) chronic hypertension (elevated resting blood pressure; as defined by Heart and Stroke Canada and Hypertension Canada), b) type 2 diabetes as defined by Diabetes Canada, with at least 5 years having elapsed since time of diagnosis
Disqualifiers
Episode(s) of severe hypoglycemia (requiring the assistance of another person) within the previous year, or inability to sense hypoglycemia (hypoglycemia unawareness).
Serious complications related to your diabetes (gastroparesis, renal disease, uncontrolled hypertension, severe autonomic neuropathy).
Uncontrolled hypertension - BP >150 mmHg systolic or >95 mmHg diastolic in a sitting position.
Restrictions in physical activity due to disease (e.g. intermittent claudication, renal impairment, active proliferative retinopathy, unstable cardiac or pulmonary disease, disabling stroke, severe arthritis, etc.).
Trial design
Design model
Crossover
Treatments tested in this trial
Simulated indoor temperature upper limit
Other interventionOlder adults exposed to an 8-hour simulated exposure.
Treatment groups
10 Participants
are divided into 4 treatment groupsGroup A: Exposure to indoor temperature upper limit without physical activity and added clothing.Experimental treatment 1 intervention
Group B: Exposure to indoor temperature upper limit with physical activity.Experimental treatment 1 intervention
Group C: Exposure to indoor temperature upper limit with added clothing.Experimental treatment 1 intervention
Group D: Exposure to indoor temperature upper limit with physical activity and added clothing.Experimental treatment 1 intervention
Trial outcomes
Primary outcomes
1
Core temperature (Peak) during daylong exposure to indoor temperature limit.
Peak rectal temperature (15 min average) during exposure. Rectal temperature is measured continuously throughout the 8 hour exposure to the simulated indoor temperature upper limit.
Time frame
End of 8 hour daylong exposureSecondary outcomes
1
Profiles of Mood States (POMS) during daylong exposure to indoor temperature limit.
Potential changes in mood (7 subscales of mood: tension, anger, depression, fatigue, confusion, vigor and esteem related affect). The POMS-40 is a validated, self-administered questionnaire that examines seven distinct aspects of mood state across two positive subscales (Esteem-Related Affect, and Vigor) and five negative subscales (Fatigue, Tension, Confusion, Anger, and Depression), which are described across 40 distinct adjectives. For each individual item, participants were asked to describe "how you feel right now" by responding using a 5-point Likert scale (0 = "Not at all", 1 = "A little", 2 = "Moderately", 3 = "Quite a lot", or 4 = "Extremely"). The values of items associated with a specific subscale (e.g., Fatigue) were summed to calculate its score.
Time frame
At the start (hour 0) and end of 8 hour daylong exposure2
Environmental Symptoms Questionnaire (ESQ) during daylong exposure to indoor temperature limit.
Self-reported environmental reactions and medical symptomatology associated with prolonged heat exposure. The ESQ-IV is a validated 68-item, self-administered questionnaire that has been used successfully in identifying symptomatology during exposure to a wide variety of environmental conditions, including heat exposure \[24, 25\]. Participants are asked to assess and described "how you have been feeling today" by responding to each item using a 6-point Likert scale (0 = "Not at all", 1 = "Slight", 2 = "Somewhat", 3 = "Moderate", 4 = "Quite a bit", or 5 = "Extreme"). Total Symptom Score was calculated from this data by taking the sum of the intensity ratings from all 68 individual items using reverse scores for the three positive items from the list ("I Felt Good", "I Felt Alert", and "I Felt Wide Awake").
Time frame
At the start (hour 0) and end of 8 hour daylong exposure3
Activity levels during daylong exposure to indoor overheating
Activity levels assessed via a wearable monitor (Actical) containing an accelerometer worn on the wrist and hip.
Time frame
End of 8 hour daylong exposure4
Hydration status during daylong exposure to indoor overheating
Hydration status measured via assessing the urine specific gravity of a urine sample.
Time frame
At the start (hour 0) and end of 8 hour daylong exposureSponsors and contacts
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Source ClinicalTrials.gov