Using wearable sensors to assess how a heatwave affects individual heat exposure, perceptions, and adaption methods.

Urban areas are typically warmer than nearby rural areas, especially during hot weather. This increases heat exposure, morbidity, and mortality rates of urban residents. Heat adaption methods can improve public safety during heat events, but the availability and usage of these resources vary based on socioeconomic and demographic characteristics, as well as personal perception of warmth. Heat events are often studied using city- and neighborhood-level meteorological and socioeconomic data, which do not reflect individual exposure or access to and use of heat adaption resources. We collected lifestyle surveys and individually experienced temperature and humidity data for 38 Knoxville, Tennessee, residents during a heatwave and a period of climatically normal summer conditions. Participants were less exposed to heat during the daytime than airport conditions suggest, indicating successful use of heat adaption methods, such as staying indoors. Some participants were warmer at night and during the non-heatwave period. Heat inequality is especially problematic at night, with older, less educated, and lower-income individuals being more exposed to heat. Even when exposed to dangerous heat levels, participants were less likely to take adaption actions to protect themselves from heat-health effects during the non-heatwave period and at night because they do not perceive themselves as being at risk or have the resources to do so. These findings signal the need for improved heat education, as future climate projections indicate an increase not only in heatwaves but also mean temperature and humidity during the warm season, and especially warmer temperatures at night.