As part of the Heat Island Reduction Initiative (HIRI) program, there is interest in determining whether the number and/or severity of days that are detrimental to human health within selected urban areas will decrease if certain heat island reduction measures are instituted. Our previous research has indicated that certain oppressive air masses have been historically associated with increasing health problems related to heat, especially respiratory-related mortality, cardiac arrests, stroke, and of course, a variety of direct heat-related illnesses. The goal of this project is to determine if the number of days within air masses historically associated with high mortality will decrease significantly if heat island reduction initiatives are put in place. In addition, we have developed a means to estimate daily heat-related mortality within these oppressive air masses, and we have calculated algorithms for various cities that forecast heatrelated mortality assuming a variety of meteorological and non-meteorological conditions. Thus, an additional goal is an estimate of heat-related mortality reduction assuming heat island reduction measures are instituted.