A Cluster Randomised Controlled Trial (cRCT) Evaluating the Effects of Cool Roofs on Health, Environmental and Economic Outcomes in Colima, Mexico
Trial Snapshot
- Phase
- Not Applicable
- Status
- Not yet recruiting
- Sponsor
- Enrollment
- 800
- Locations
- 1
- Primary Endpoint
- Resting heart rate
Study Overview
Brief Summary
Ambient air temperatures in Mexico have broken record highs in 2024. Solutions are needed to build heat resilience in communities and adapt to increasing heat from climate change. Sunlight-reflecting cool roof coatings may passively reduce indoor temperatures and energy use to protect home occupants from extreme heat. Occupants living in poor housing conditions in the northern zone of Mexico are susceptible to increased heat exposure.
Heat exposure can instigate and worsen numerous physical, mental and social health conditions. The worst adverse health effects are experienced in communities that are least able to adapt to heat exposure. By reducing indoor temperatures, cool roof use can promote physical, mental and social wellbeing in household occupants.
The long-term research goal of the investigators is to identify viable passive housing adaptation technologies with proven health benefits to reduce the burden of heat stress in communities affected by heat in Mexico. To meet this goal, the investigators will conduct a cluster-randomized controlled trial to establish the effects of cool roof use on health, indoor environment and economic outcomes in Colima, Mexico.
Detailed Description
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, are 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, populations 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 cluster-randomized controlled trial investigating the effects of cool-roof use on health, environmental and economic outcomes 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 policy responses on scaling cool roof implementation to protect people from increasing heat exposure driven by climate change.
Study Design
- Study Type
- Interventional
- Allocation
- Randomized
- Intervention Model
- Parallel
- Primary Purpose
- Prevention
- Masking
- Double (Investigator, Outcomes Assessor)
Masking Description
Trial participants will be aware of the intervention to which they have been allocated, and the research fieldworkers will be aware of the intervention allocation. The trial steering committee members and trial statistician will remain blinded until the end of trial period and data collection.
Eligibility Criteria
- Ages
- 18 Years to — (Adult, Older Adult)
- Sex
- All
- Accepts Healthy Volunteers
- Yes
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.
Arms & Interventions
Cool roof
Households will receive sunlight reflecting 'cool roof' coating on their roofs.
Intervention: Cool roof (Other)
No cool roof
No cool roof application. Households will keep their original roofing for the duration of the trial.
Outcomes
Primary Outcomes
Resting heart rate
Time Frame: Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.
Resting heart rate in beats per minute measured as the average of three readings in the left arm over one hour using portable automated sphygmomanometers.
Blood glucose control
Time Frame: Two measurements will be taken: one at baseline and one in the last month of three consecutive hottest months.
Three month average of blood glucose in mmol/mol measured as glycosylated hemoglobin (HbA1c) using capillary blood and the HemoCue® HbA1c 501 System.
Depression
Time Frame: Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.
Self-reported presence and frequency of symptoms of depression assessed using aggregate score of the Patient Health Questionnaire 9 (PHQ-9). Minimum score of 0 and a maximum score of 27 with a higher score meaning a worse outcome.
Secondary Outcomes
- Heat-related symptoms(Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.)
- Physician diagnosed heat-related illnesses(Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.)
- Food insecurity(Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.)
- Diet quality(Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.)
- Health-related quality of life(Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.)
- Indoor thermal comfort(Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.)
- Coping ability(Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.)
- Life satisfaction(Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.)
- Healthcare provider utilization(Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.)
- Hospitalization(Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.)
- Systolic Blood Pressure(Eight measurements will be taken: one at baseline and seven over 12 months, covering the three consecutive hottest months and four alternate months.)
- Diastolic Blood Pressure(Eight measurements will be taken: one at baseline and seven over 12 months, covering the three consecutive hottest months and four alternate months.)
- Cognition(Eight measurements: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.)
- Inner Ear Canal Temperature(Eight measurements will be taken: one at baseline and seven over 12 months, covering the three consecutive hottest months and four alternate months.)
- Dehydration(Eight measurements will be taken: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.)
- Sleep quality(Eight measurements: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.)
- Aggression(Eight measurements: one at baseline and seven over 12 months, covering three consecutive hottest months and four alternate months.)
- Productivity(Eight measurements will be taken: one at baseline and seven over 12 months, covering the three consecutive hottest months and four alternate months.)
- Indoor air temperature(Measurements at 15 minute intervals for 12 months.)
- Indoor relative humidity(Measurements at 15 minute intervals for 12 months.)
- Indoor heat index(Measurements at 15 minute intervals for 12 months.)
- Household energy expenditure(Eight measurements will be taken: one at baseline and seven over 12 months, covering the three consecutive hottest months and four alternate months.)
Investigators
Aditi Bunker
Co-principal investigator
University of Auckland, New Zealand