The aim of the study discussed here was to determine the associations among the urban heat island (UHI), air quality, and hospital respiratory admissions in the warm center of an urban area. The authors collected and analyzed the data regarding air quality parameters, meteorological parameters, and the daily hospital respiratory admissions in the Taichung metropolis in the autumns of 2003 and 2004. By collecting the vertical meteorological parameters and air pollutant concentrations via the tethersonde balloon technique, the authors simulated convergence in Dali using The Air Pollution Model (TAPM) for the atmospheric conditions. The authors also examined the hypotheses with Duncan's Multiple Range test, and analyzed spatial patterns vis-à-vis air temperature, air quality, and hospital respiratory admissions with GIS. The results indicated that the UHI phenomenon-which generates convergence and then transports air pollutants to a metropolitan area-increases hospital respiratory admissions in the warm center of an urban area.