Assessing the Effect of Cool Roofs on Health Using Smartwatches in Colima, Mexico

Increasing heat exposure from climate change is causing and exacerbating heat-related illnesses in millions worldwide - particularly in low-resource settings. June 2024 was the 13th consecutive hottest month on record globally - shattering previous records. Heat exposure can instigate and worsen health conditions, including cardiovascular, metabolic, endocrine and respiratory disease, heat-related illnesses, pregnancy complications, and mental health conditions. Adaptation is essential for protecting people from increasing heat exposure. The built environment, especially homes, is ideal for deploying interventions to reduce heat exposure and accelerate adaptation efforts. However, there currently is a lack of evidence on a global scale - generated through empirical studies - guiding the uptake of interventions to reduce heat stress in low-resource settings.

Cities and towns of LMIC are among the most vulnerable to the adverse impacts of climate change and are likely to experience increases in ambient air temperature over the coming decades. People in Colima are exposed to heat and low humidity year-round. The combined burden of heat and NCDs places Colima's population at greater risk of adverse health effects from heat extremes.

Sunlight-reflecting cool roof coatings passively reduce indoor temperatures and lower energy use, offering protection to home occupants from extreme heat. The investigators therefore aim to conduct a randomized controlled trial investigating the effects of cool roofs on heart rate, sleep and physical activity using smartwatches in Colima.

The trial will quantify whether cool roofs are an effective passive home cooling intervention with beneficial health effects for vulnerable populations in Colima. Findings will inform regional and global policy responses on scaling cool roof implementation to protect people from increasing heat exposure driven by climate change.

Inclusion criteria

• Permanent household resident

Exclusion criteria

• Roof damage, inaccessible or instability of roof adversely affecting cool roof coating application.
• Participant unable to provide written/verbal informed consent. Participants will be excluded if they are not willing or able to wear a smartwatch.
• Participants will be excluded if they do not have a smartphone with an internet connection that can connect to the smartwatch.
• Only one participant per household.