JMIR Publications

ABSTRACT

Background:

Extreme weather, including heat and heavy rainfall, is projected to increase due to climate change, which can have adverse impacts on human health. Particularly, rural populations in sub-Saharan Africa are at risk because of a high burden of climate-sensitive diseases and low adaptive capacities. However, there is a lack of data in the regions that are anticipated to be most exposed to climate change. Better public health surveillance is essential for better decision-making and health prioritization, and to identify risk groups and suitable adaptation measures. To this end, digital technologies like consumer-grade wearable devices (wearables) may generate objective measurements to guide data-driven decision making.

Objective:

The main objective of this observational study was to examine the impact of weather exposures on population health in rural Burkina Faso using wearables. Specifically, the study aimed to assess the relationship between individual daily activity (steps), sleep duration and heart rate (HR) as estimated by wearables, and exposure to heat and heavy rainfall.

Methods:

A total of n=143 study participants from the Nouna Health and Demographic Surveillance System (HDSS) in Burkina Faso wore the Withings Pulse HR wearable 24/7 for 11 months. We collected continuous weather data with five weather stations throughout the study region. Heat Index (HI) and Wet Bulb Globe Temperature (WBGT) were calculated as measures for heat. We used linear mixed effects models to quantify the relation between exposures to heat and rainfall and the wearable parameters. Participants kept activity journals and completed a questionnaire on their perception of, and adaptation to, heat and other weather exposures.

Results:

Sleep duration decreased significantly with higher heat exposure, with approximately 15 minutes shorter sleep during heat stress nights with HI≥25°C. Many participants (n=55) reported that heat affected them most at night. During the day, most participants (n=133) engaged in outdoor physical work, like farming, housework or fetching water. During the rainy season, when WBGT was highest, daily activity was highest and increased when daily maximum WBGT surpassed 30°C during the rainiest month. In the hottest month, daily activity decreased per degree increase in WBGT for values over 30°C. Nighttime HR showed no statistically significant correlation with heat exposure. Daytime HR data had insufficient data for analysis. We found no negative health impact associated with heavy rainfall. With increasing rainfall, sleep duration increased, average nightly HR decreased, and activity decreased.

Conclusions:

During the study period, participants were frequently exposed to heat and heavy rainfall. Heat was especially associated with impaired sleep and daily activity. Essential tasks like harvesting, fetching water, and caring for livestock expose this population to weather that likely has an adverse impact on their health. Consequently, further research is needed for better decision-making and to inform interventions and adaptations to protect vulnerable communities.