Indoor Temperature for Heat Stress

This trial aims to examine how indoor temperature affects older adults' body temperature and heart health, particularly when they wear extra clothing or engage in light activities. It tests whether the recommended indoor temperature of 26°C remains safe when combined with everyday actions and various clothing choices. Ideal participants are non-smokers aged 65-85 who speak English or French and have had stable high blood pressure or type 2 diabetes for at least five years. As an unphased trial, this study provides a unique opportunity to contribute to understanding how everyday environments impact health.

The trial does not specify if you need to stop taking your current medications. However, if you or the investigators think your medication use makes it inadvisable to participate, it might affect your eligibility.

Research has shown that hot indoor environments can lead to heat stress, causing issues like heat exhaustion and heat stroke, particularly in older adults. The World Health Organization notes that heat stress is a major cause of weather-related deaths and can worsen existing health problems like heart disease and diabetes.

In this study, participants stay in rooms with temperatures of 26°C (78.8°F) while wearing light clothing, sometimes with extra layers or engaging in light exercise. Although 26°C is usually comfortable, added activity or clothing can increase heat stress. Research indicates that temperatures over 27°C (80.6°F) might raise the risk of health problems.

Researchers are excited about this trial because it aims to explore how different indoor temperature conditions impact heat stress. Unlike typical approaches that might focus on cooling devices like fans or air conditioning, this trial looks at how variations in clothing and physical activity at a constant temperature can affect the body's response to heat. By examining these everyday factors, the trial could uncover new strategies for managing heat stress in environments where temperature control is limited. This could lead to practical guidelines that help people stay comfortable and safe during hot weather without relying solely on external cooling methods.

This trial will evaluate the effects of different indoor temperature conditions on health and comfort. Research has shown that high indoor temperatures can harm health and comfort. Studies found that for every 1°C increase in indoor temperature, feelings of discomfort due to heat rise by 33%, and sleep problems increase by 24%. Warmer indoor spaces also correlate with health issues and lower overall well-being. To reduce these risks, experts recommend maintaining indoor temperatures at or below 26°C with 45% humidity. This setting is especially protective for older adults, who are more sensitive to heat. Participants in this trial will experience an indoor temperature maintained at 26°C and 45% relative humidity under various conditions, including with or without activity and with or without added clothing layers.¹³⁶⁷⁸