Heat island effect aggravates mortality

Kaufui V. Wong, Andrew Paddon, Alfredo Jimenez

Research output: Chapter in Book/Report/Conference proceedingConference contribution

3 Scopus citations


Cases of death during heat waves are most commonly due to respiratory and cardiovascular diseases, with the main contribution from the negative effect of heat on the cardiovascular system. In an attempt to control the body temperature, the body's natural instinct is to circulate large quantities of blood to the skin. However while trying to protect itself from overheating, the body actually harms itself by inducing extra strain on the heart. This excess strain has the potential to trigger a cardiac event in those with chronic health problems, such as the elderly. Those in the U.S.A. between the ages of 65 and 74 are at a higher risk of mortality during heat waves when they are single, have a history of chronic pulmonary disease, or suffer from a psychiatric disorder. In the older group, 75+, single people are again more vulnerable as well as women. The relationship of mortality and temperature creates a J-shaped function, showing a steeper slope at higher temperatures. Records show that more casualties have resulted from heat waves than hurricanes, floods, and tornadoes together. The significance of this is that the U.S. suffers the highest damage total from natural catastrophes annually. Studies held from 1989-2000 in 50 U.S. cities recorded 1.6% more deaths during cold temperature events, as opposed to a staggering 5.7% increase during heat waves. People are at risk when living in large metropolitan areas, especially those mentioned above, due to the heat island effect. Urban areas suffer heat increases from the combination of global warming effects as well as localized heat island properties. It is flawed to claim that the contribution of anthropogenic heat generation to the heat island effect is small. Analyzing the trend of extreme heat events (EHEs) between 1956 and 2005 showed an increase on average of 0.20 days/year, on a 95% confidence interval with uncertainty of ±0.6. This trend follows the recorded data for 2005 with 10 more heat events per city than in 1956. Compact cities experience an average of 5.6 days of extreme heat conditions annually, compared to that of 14.8 for sprawling cities. The regional climate, city populace, or pace of population growth however does not affect this effect. Statistics from the U.S. Census state that the U.S. population without air conditioning saw a drop of 32% from 1978 to 2005, resting at 15%. Despite the increase in air conditioning use, the positive affects of it may have run their course as a critical point may have been reached. A study done by Kalkstein through 2007 proved that the shielding effects of air conditioning reached their terminal effect in the mid-1990s. Heat-related illnesses and mortality rates have slightly decreased since 1980, regardless of the increase in temperatures. This may be in part to the increase in availability of air conditioning, and other protective measures, to the public. Protective factors have mitigated the danger of heat on those vulnerable to it, however projecting forward the heat increment related to sprawl may exceed physiologic adaptation thresholds.

Original languageEnglish (US)
Title of host publicationEnergy Systems Analysis, Thermodynamics and Sustainability; Combustion Science and Engineering; Nanoengineering for Energy
PublisherAmerican Society of Mechanical Engineers (ASME)
Number of pages15
ISBN (Print)9780791854907
StatePublished - 2011
EventASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011 - Denver, CO, United States
Duration: Nov 11 2011Nov 17 2011

Publication series

NameASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011


OtherASME 2011 International Mechanical Engineering Congress and Exposition, IMECE 2011
Country/TerritoryUnited States
CityDenver, CO

ASJC Scopus subject areas

  • Mechanical Engineering


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