Mortality displacement refers to the deaths that occur during a heat wave that would have occurred anyway in a near future, but which were precipitated by the heat wave itself. In other words, people who are already very ill and close to death (expected to die, for instance, within days or a few weeks) might die sooner than they might have otherwise, because of the impact of the heat wave on their health. However, because their deaths have been hastened by the heat wave, in the months that follow the number of deaths becomes lower than average. This is also called a harvesting effect, in which part of the expected (future) mortality shifts forward a few weeks to the period of the heat wave. Initially some public officials suggested that the high death toll during the weeks of the heat wave was due to mortality displacement; an analysis of the data later found that mortality displacement during the heat wave was limited to about 26% of the estimated 692 excess deaths in the period between June 21 and August 10, 1995. Mortality risks affected Black residents disproportionally. Appropriately targeted interventions may have a tangible effect on life expectancy.
