It is still difficult to confirm from available data if global warming and climate changes have played a role in increasing heat-related injuries. However, it is certain that global warming can increase the frequency and intensity of heat waves, which can cause discomfort to the human body and, in the worst case, can lead to more heat illness casualties. Recent worldwide natural disasters, such as the Tohoku earthquake in Japan, flooding in Thailand, and the Pakistan heat wave show that climate change is truly a fact. Heat-related deaths resulting from climate change are becoming increasingly serious around the world as such abnormal weather phenomena have occurred each year in the past decade causing a large number of deaths, particularly of the elderly. The nation of Japan faced a huge problem in energy shortage after the Fukushima nuclear explosion. Various energy-saving strategies were adopted to combat hot weather during the following summer in Japan. Passive cooling through natural ventilation is deemed to be one of the most effective strategies against the shortage of energy and hot weather. This paper gives an overview of some extreme hot weather incidents worldwide and discusses the important role of natural ventilation from three different aspects: energy shortage, indoor air quality control and human body comfort. A current human thermoregulation study being carried out in Japan is also described.
