Extreme heat events--a community calamity.

a growing global concern that teeming millions might be at greater risk of death, disease and disability due to extreme heat events in the tropics and other regions. It has been estimated that about 48 million people were affected in Asia during the year 2008, due to climatological, geophysical, hydrological and meteorological events. Despite projection of changing climate and occurrence of increased frequency and intensity of extreme heat events in the coming years, the public recognition of the silent killer remains subdued. The heat-related mortalities that might be grave during a given year in a region do not leave a lasting reminder. For much of the tropical world, including the vast Indian subcontinent, the situation is potentially dire, as these regions continue to witness such community calamity at regular intervals over the centuries. Besides naturally occurring hot climates, occupational situations, such as open field tropical farming, glass and ceramic production, molten metal operations, and many other hot industrial processes cause heat stress and strain 1). Risks of heat induced human illnesses prevail, with relative vulnerability to children, elderly, pregnant mothers, and those with pre-existing medical conditions, such as obesity, cardiovascular and neurological diseases. Urban and rural poor dwelling in the slums and pavement, outdoor construction workers, street venders, rickshaw pullers and others, face adverse health effects, due to their low physiological adaptive capacity, lack of awareness of the risks, as well as non-feasibility of adopting any mit-igation measures. Climate change being real and fast happening, the current hot zones will continue to confront with extreme heat wave episodes, and also currently not affected geographic areas might be affected in the coming decades. The World Meteorology Organization defines heat wave when the average maximum temperature is greater than 5˚C above the normal range for five consecutive days. Alternatively, it has been defined as the average maximum temperature exceeding 97.5th percentile level for at least three days, and above 81st percentile level for the entire period. The average minimum temperature may exceed 97.5th percentile level for 3 days. According to Indian Meteorology Department, one category of heat wave includes places where the normal maximum temperature is more than 40˚C. In such regions, the day temperature exceeds by 3 to 4˚C above the normal. When the day temperature is 5˚C or more than the normal, the severe heat wave conditions persist. The other category considers the regions where the normal maximum temperature is …