Data Considerations for Estimating Ambient Heat Exposure for Environmental Epidemiological Studies

Extreme heat is a public health threat. We review common meteorological data sets and metrics for estimating heat in epidemiologic studies and recommend practical advice for those just starting in this field.

Heat can be estimated through a variety of approaches that differ in their spatial resolution, temporal frequency, historical extent, aggregation, and population coverage. Heat exposure is operationalized as air temperature, but heat indices including additional variables (e.g. humidity, solar radiation, wind) capturing different physiological pathways and varying in their availability and interpretability are common. Defining heat waves for research and government activation is another important consideration in terms of risk and perception. Other analysis choices include defining extreme heat thresholds, population-weighting, or special considerations in urban environments. We suggest practical guidance for selecting data and metrics for specific heat health epidemiologic questions. No single "best" heat metric exists; investigators should consider their research question, population, and data availability to identify the most appropriate approaches.