Respiratory hospital admissions and weather changes: a retrospective study in Charlottesville, Virginia, USA.

In most midlatitude locations, human morbidity and mortality are highly seasonal, with winter peaks driven by respiratory disease and associated comorbidities. But the transition between high and low mortality/morbidity months varies spatially. We use a measure of the thermal biophysical strain imposed on the respiratory system-the Acclimatization Thermal Strain Index (ATSI)-to examine respiratory hospital admissions in Charlottesville, VA. Daily respiratory admissions to the University of Virginia over a 19-year period are compared to ATSI values derived from hourly surface weather data acquired from the Charlottesville airport. Negative ATSI values (associated with transitions from warm (and humid) to cold (and dry) conditions) are related to admission peaks at seasonal and weekly timescales, whereas positive ATSI values (cold to warm) exhibit weaker relationships. This research marks the first application of the ATSI to human morbidity, and results suggest that respiratory strain may account for how people who are acclimated to different climates respond to short-term weather changes.