Intra-Neighborhood Variation in Individually Experienced Temperatures (IETs): Insights from a New Approach to Measuring Heat Exposure

Urban environmental health hazards, including exposure to extreme heat, have become increasingly important to understand in light of ongoing climate change and urbanization. In cities, neighborhoods are often considered a homogenous and appropriate unit with which to assess heat risk. This paper presents results from a pilot study examining the variability of individually experienced temperatures (IETs) within a single urban neighborhood. In July 2013, 23 research participants were recruited from Boston's South End neighborhood and equipped with Thermochron iButtons that measured the air temperatures surrounding individuals as they went about their daily lives. The researcher asked participants to fill out daily surveys, conducted exit interviews, and engaged in a field ethnography during the summer months. IETs were measured during a heat wave period (July 18-20), which included two excessive heat warnings and a heat advisory, as well as a reference period (July 21-23) in which temperatures were below seasonal averages. IETs were not homogeneous during the heat wave period and the majority of participants recorded IETs significantly lower than outdoor ambient temperatures. More than half of participants did not experience statistically different temperatures between the two test periods, despite the fact that mean outdoor temperatures were 6.5˚C higher during the heat wave period. The IET data collected for this sample and study period suggest that heterogeneity in individual heat exposure can exist within a neighborhood and that outdoor temperatures overestimate mean experienced temperatures during a heat wave. Findings from daily surveys and exit interviews suggest that behavior (schedules, preferences, lifestyles) and access to cooling resources (air-conditioned homes and business, parks, and pools) were variable among participants. Further, Individual attributes such as gender, race, socioeconomic status, age, and neighborhood tenure, also proved important in predicting heat exposure. Individual heat exposure can best be understood when the intersection of individual attributes, behavior, and access to cooling resources are framed by the neighborhood social and biophysical context. Individual differences are an overlooked determinant of heat exposure and should be better integrated into multi-scalar analyses. Understanding IETs for the population at large may lead to innovative advances in heat-health intervention and mitigation strategies.