1995 Chicago heat wave
Encyclopedia
The 1995 Chicago heat wave was a heat wave
which led to approximately 750 heat-related deaths in Chicago
over a period of five days. Eric Klinenberg
, author of the 2002 book Heat Wave: A Social Autopsy of Disaster in Chicago, has noted that in the United States
, the loss of human life in hot spells in summer exceeds that caused by all other weather events combined, including lightning
, rain, flood
s, hurricanes, and tornado
es. The heat wave heavily impacted the wider Midwestern region, with additional deaths in both St. Louis, Missouri
and Milwaukee, Wisconsin, as well.
At the peak of the heat wave, as was the case in the summer of 1988, and possibly 1977, Madison, Wisconsin probably would have broken its all-time maximum temperature record of 107 °F (41.7 °C) had the reporting station been in the same location as it was during the 1930s.
The humidity made a large difference for the heat in this heat wave when compared to the majority of those of the 1930s, 1988, 1976–78 and 1954–56, which were powered by extremely hot, dry, bare soil and/or air masses which had originated in the desert South-West. Each of the above mentioned years' summers did indubitably have high-humidity heat waves as well, although 1988 was a possible exception in some areas. Moisture from previous rains and transpiration by plants drove up the humidity to record levels and the most humid air mass originated over Iowa previous to and during the early stages of the heat wave. Numerous stations in Iowa, Wisconsin, Illinois and elsewhere reported record dew point
temperatures above 80 °F (26.7 °C) with a probable peak at 86 °F (30 °C) reported from at least one station in Wisconsin on 13 July 1995; this added to the heat to cause heat indices above 130 °F (54.4 °C) in Iowa and southern Wisconsin on several days of the heat wave as the sun bore down from a cloudless sky and evaporated even more water seven days in a row.
A more typical result of surface dew points above 80 °F (26.7 °C) are extreme precipitable water readings as well as other indices used to forecast severe thunderstorms and flooding such as Convective available potential energy
as was illustrated in early June 2008 when thunderstorms originating in Minnesota and Iowa mushroomed when hitting the area of extreme dew points in South-Central and South-East Wisconsin from 77 to 84 °F (25 to 28.9 C) and inaugurated the third wave of upper Middle West flooding (the first was snowmelt from the record-breaking winter snows and the third was the widespread rains in excess of 10 inches (250 mm) and up to 21 inches (530 mm) during early August 1997) by producing extremely heavy rain over the region, with many areas receiving 5 inches (130 mm) and a few areas of 10 to 15 inches (250 to 380 mm) in 3 to 6 hours' time.
A few days after, the heat moved to the east, with temperatures in Pittsburgh, Pennsylvania
reaching 100 °F (37.8 °C) and in Danbury, Connecticut
, 106 °F (41.1 °C) which is Connecticut's highest recorded temperature.
The dew points in question appear to be at or near national and continental records set a various times in the past; dew point records are not as widely kept as those of temperature and so on. Evidence points to the world record most likely being close to or in excess of 100 °F (37.8 °C) at locations along the Red Sea coast of Saudi Arabia.
or could not afford to turn it on. Many older citizens were also hesitant to open windows and doors at night for fear of crime
. Elderly women, who may have been more socially engaged, were less vulnerable than elderly men. By contrast, during the heat waves of the 1930s, many residents slept outside in the parks or along the shore of Lake Michigan
.
Because of the nature of the disaster, and the slow response of authorities to recognize it, no official "death toll" has been determined. However, figures show that 739 additional people died in that particular week above the usual weekly average. Further epidemiologic analysis showed that blacks were more likely to die than whites, and that Hispanics had an unusually low death rate due to heat. At the time, many blacks lived in areas of sub-standard housing and less cohesive neighborhoods, while Hispanics at the time lived in places with higher population density, and more social cohesion.
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 Blacks disproportionally. Appropriately targeted interventions may have a tangible effect on life expectancy.
that raised nocturnal temperatures by more than 2 C-change. Urban heat islands are caused by the concentration of buildings and pavement in urban areas, which tend to absorb more heat in the day and radiate less heat at night into their immediate surroundings than comparable rural sites. Therefore, built-up areas get hotter and stay hotter.
Other aggravating factors were inadequate warnings, power failures, inadequate ambulance
service and hospital facilities, and lack of preparation. City officials did not release a heat emergency warning until the last day of the heat wave. Thus, such emergency measures as Chicago's five cooling center
s were not fully utilized. The medical system of Chicago was severely taxed as thousands were taken to local hospitals with heat-related problems. In some cases, fire trucks were used as substitute ambulances.
Another powerful factor in the heat wave was that a temperature inversion grew over the city, and air stagnated in this situation. Pollutants and humidity
were confined to ground level, and the air was becalmed and devoid of wind
. Without wind to stir the air, temperatures grew even hotter than could be expected with just an urban heat island, and without wind there was truly no relief. Without any way to relieve the heat, even the inside of homes became ovens, with indoor temperature exceeding 90 °F (32.2 °C) at night. This was especially noticeable in areas which experienced frequent power outages. At Northwestern University just north of Chicago, summer school students lived in dormitories without air conditioning. In order to ease the effects of the heat, some of the students slept at night with water-soaked towels as blankets.
The scale of the human tragedy sparked denial in some quarters, grief and blame elsewhere. From the moment the local medical examiner began to report heat-related mortality figures, political leaders, journalists, and in turn the Chicago public have actively denied the disaster's significance. Although so many city residents died that the coroner had to call in nine refrigerated trucks to store the bodies, skepticism about the trauma continues today. In Chicago, people still debate whether the medical examiner exaggerated the numbers and wonder if the crisis was a "media event." The American Journal of Public Health established that the medical examiner's numbers actually undercounted the mortality by about 250 since hundreds of bodies were buried before they could be autopsied.
During the week of the heat wave, there were 11% more hospital admissions than average for comparison weeks and 35% more than expected among patients aged 65 years and older. The majority of this excess (59%) were treatments for dehydration, heat stroke, and heat exhaustion.
Heat wave
A heat wave is a prolonged period of excessively hot weather, which may be accompanied by high humidity. There is no universal definition of a heat wave; the term is relative to the usual weather in the area...
which led to approximately 750 heat-related deaths in Chicago
Chicago
Chicago is the largest city in the US state of Illinois. With nearly 2.7 million residents, it is the most populous city in the Midwestern United States and the third most populous in the US, after New York City and Los Angeles...
over a period of five days. Eric Klinenberg
Eric Klinenberg
Eric Klinenberg is an American sociologist and a scholar of urban studies, culture, and media. He is best known for his contributions as a public sociologist....
, author of the 2002 book Heat Wave: A Social Autopsy of Disaster in Chicago, has noted that in the United States
United States
The United States of America is a federal constitutional republic comprising fifty states and a federal district...
, the loss of human life in hot spells in summer exceeds that caused by all other weather events combined, including lightning
Lightning
Lightning is an atmospheric electrostatic discharge accompanied by thunder, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms...
, rain, flood
Flood
A flood is an overflow of an expanse of water that submerges land. The EU Floods directive defines a flood as a temporary covering by water of land not normally covered by water...
s, hurricanes, and tornado
Tornado
A tornado is a violent, dangerous, rotating column of air that is in contact with both the surface of the earth and a cumulonimbus cloud or, in rare cases, the base of a cumulus cloud. They are often referred to as a twister or a cyclone, although the word cyclone is used in meteorology in a wider...
es. The heat wave heavily impacted the wider Midwestern region, with additional deaths in both St. Louis, Missouri
St. Louis, Missouri
St. Louis is an independent city on the eastern border of Missouri, United States. With a population of 319,294, it was the 58th-largest U.S. city at the 2010 U.S. Census. The Greater St...
and Milwaukee, Wisconsin, as well.
Weather
The temperatures soared to record highs in July with the hottest weather occurring from July 12 to July 16. The high of 106 °F (41.1 °C) on July 13 was the second warmest July temperature (warmest being 110 °F (43.3 °C) set on July 23, 1934) since records began at Chicago Midway International Airport in 1928. Nighttime low temperatures were unusually high; in the upper 70s and lower 80s °F (about 26 °C)—as well. Record humidity levels also accompanied the hot weather. The heat index reached 119 °F (48.3 °C) at O'Hare airport, and 125 °F (51.7 °C) at Midway Airport.At the peak of the heat wave, as was the case in the summer of 1988, and possibly 1977, Madison, Wisconsin probably would have broken its all-time maximum temperature record of 107 °F (41.7 °C) had the reporting station been in the same location as it was during the 1930s.
The humidity made a large difference for the heat in this heat wave when compared to the majority of those of the 1930s, 1988, 1976–78 and 1954–56, which were powered by extremely hot, dry, bare soil and/or air masses which had originated in the desert South-West. Each of the above mentioned years' summers did indubitably have high-humidity heat waves as well, although 1988 was a possible exception in some areas. Moisture from previous rains and transpiration by plants drove up the humidity to record levels and the most humid air mass originated over Iowa previous to and during the early stages of the heat wave. Numerous stations in Iowa, Wisconsin, Illinois and elsewhere reported record dew point
Dew point
The dew point is the temperature to which a given parcel of humid air must be cooled, at constant barometric pressure, for water vapor to condense into liquid water. The condensed water is called dew when it forms on a solid surface. The dew point is a saturation temperature.The dew point is...
temperatures above 80 °F (26.7 °C) with a probable peak at 86 °F (30 °C) reported from at least one station in Wisconsin on 13 July 1995; this added to the heat to cause heat indices above 130 °F (54.4 °C) in Iowa and southern Wisconsin on several days of the heat wave as the sun bore down from a cloudless sky and evaporated even more water seven days in a row.
A more typical result of surface dew points above 80 °F (26.7 °C) are extreme precipitable water readings as well as other indices used to forecast severe thunderstorms and flooding such as Convective available potential energy
Convective available potential energy
In meteorology, convective available potential energy , sometimes, simply, available potential energy , is the amount of energy a parcel of air would have if lifted a certain distance vertically through the atmosphere...
as was illustrated in early June 2008 when thunderstorms originating in Minnesota and Iowa mushroomed when hitting the area of extreme dew points in South-Central and South-East Wisconsin from 77 to 84 °F (25 to 28.9 C) and inaugurated the third wave of upper Middle West flooding (the first was snowmelt from the record-breaking winter snows and the third was the widespread rains in excess of 10 inches (250 mm) and up to 21 inches (530 mm) during early August 1997) by producing extremely heavy rain over the region, with many areas receiving 5 inches (130 mm) and a few areas of 10 to 15 inches (250 to 380 mm) in 3 to 6 hours' time.
A few days after, the heat moved to the east, with temperatures in Pittsburgh, Pennsylvania
Pittsburgh, Pennsylvania
Pittsburgh is the second-largest city in the US Commonwealth of Pennsylvania and the county seat of Allegheny County. Regionally, it anchors the largest urban area of Appalachia and the Ohio River Valley, and nationally, it is the 22nd-largest urban area in the United States...
reaching 100 °F (37.8 °C) and in Danbury, Connecticut
Danbury, Connecticut
Danbury is a city in northern Fairfield County, Connecticut, United States. It had population at the 2010 census of 80,893. Danbury is the fourth largest city in Fairfield County and is the seventh largest city in Connecticut....
, 106 °F (41.1 °C) which is Connecticut's highest recorded temperature.
The dew points in question appear to be at or near national and continental records set a various times in the past; dew point records are not as widely kept as those of temperature and so on. Evidence points to the world record most likely being close to or in excess of 100 °F (37.8 °C) at locations along the Red Sea coast of Saudi Arabia.
Victims
Most of the heat wave victims were the elderly poor living in the heart of the city, who either had no working air conditioningAir conditioning
An air conditioner is a home appliance, system, or mechanism designed to dehumidify and extract heat from an area. The cooling is done using a simple refrigeration cycle...
or could not afford to turn it on. Many older citizens were also hesitant to open windows and doors at night for fear of crime
Crime
Crime is the breach of rules or laws for which some governing authority can ultimately prescribe a conviction...
. Elderly women, who may have been more socially engaged, were less vulnerable than elderly men. By contrast, during the heat waves of the 1930s, many residents slept outside in the parks or along the shore of Lake Michigan
Lake Michigan
Lake Michigan is one of the five Great Lakes of North America and the only one located entirely within the United States. It is the second largest of the Great Lakes by volume and the third largest by surface area, after Lake Superior and Lake Huron...
.
Because of the nature of the disaster, and the slow response of authorities to recognize it, no official "death toll" has been determined. However, figures show that 739 additional people died in that particular week above the usual weekly average. Further epidemiologic analysis showed that blacks were more likely to die than whites, and that Hispanics had an unusually low death rate due to heat. At the time, many blacks lived in areas of sub-standard housing and less cohesive neighborhoods, while Hispanics at the time lived in places with higher population density, and more social cohesion.
Mortality displacement
Mortality displacement
Mortality displacement denotes a temporal shift in the rate of mortality in a given population, usually attributable to environmental phenomena such as heat waves or cold spells....
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 Blacks disproportionally. Appropriately targeted interventions may have a tangible effect on life expectancy.
Aggravating factors
Impacts in the Chicago urban center were exacerbated by an urban heat islandUrban heat island
An urban heat island is a metropolitan area which is significantly warmer than its surrounding rural areas. The phenomenon was first investigated and described by Luke Howard in the 1810s, although he was not the one to name the phenomenon. The temperature difference usually is larger at night...
that raised nocturnal temperatures by more than 2 C-change. Urban heat islands are caused by the concentration of buildings and pavement in urban areas, which tend to absorb more heat in the day and radiate less heat at night into their immediate surroundings than comparable rural sites. Therefore, built-up areas get hotter and stay hotter.
Other aggravating factors were inadequate warnings, power failures, inadequate ambulance
Ambulance
An ambulance is a vehicle for transportation of sick or injured people to, from or between places of treatment for an illness or injury, and in some instances will also provide out of hospital medical care to the patient...
service and hospital facilities, and lack of preparation. City officials did not release a heat emergency warning until the last day of the heat wave. Thus, such emergency measures as Chicago's five cooling center
Cooling center
A cooling center is a temporary air-conditioned public space set up by local authorities to deal with the health effects of a heat wave. Usually sited at several locations throughout a city, cooling centers are meant to prevent hyperthermia, especially among the elderly without air conditioning at...
s were not fully utilized. The medical system of Chicago was severely taxed as thousands were taken to local hospitals with heat-related problems. In some cases, fire trucks were used as substitute ambulances.
Another powerful factor in the heat wave was that a temperature inversion grew over the city, and air stagnated in this situation. Pollutants and humidity
Humidity
Humidity is a term for the amount of water vapor in the air, and can refer to any one of several measurements of humidity. Formally, humid air is not "moist air" but a mixture of water vapor and other constituents of air, and humidity is defined in terms of the water content of this mixture,...
were confined to ground level, and the air was becalmed and devoid of wind
Wind
Wind is the flow of gases on a large scale. On Earth, wind consists of the bulk movement of air. In outer space, solar wind is the movement of gases or charged particles from the sun through space, while planetary wind is the outgassing of light chemical elements from a planet's atmosphere into space...
. Without wind to stir the air, temperatures grew even hotter than could be expected with just an urban heat island, and without wind there was truly no relief. Without any way to relieve the heat, even the inside of homes became ovens, with indoor temperature exceeding 90 °F (32.2 °C) at night. This was especially noticeable in areas which experienced frequent power outages. At Northwestern University just north of Chicago, summer school students lived in dormitories without air conditioning. In order to ease the effects of the heat, some of the students slept at night with water-soaked towels as blankets.
The scale of the human tragedy sparked denial in some quarters, grief and blame elsewhere. From the moment the local medical examiner began to report heat-related mortality figures, political leaders, journalists, and in turn the Chicago public have actively denied the disaster's significance. Although so many city residents died that the coroner had to call in nine refrigerated trucks to store the bodies, skepticism about the trauma continues today. In Chicago, people still debate whether the medical examiner exaggerated the numbers and wonder if the crisis was a "media event." The American Journal of Public Health established that the medical examiner's numbers actually undercounted the mortality by about 250 since hundreds of bodies were buried before they could be autopsied.
Statistics
Chicago's daily low and high in 1995:- July 11: 73-90 °F (23-32 °C)
- July 12: 76-98 °F (24-37 °C)
- July 13: 81-106 °F (27-41 °C)
- July 14: 84-102 °F (29-39 °C)
- July 15: 77-99 °F (25-37 °C)
- July 16: 76-94 °F (24-34 °C)
- July 17: 73-89 °F (23-32 °C)
During the week of the heat wave, there were 11% more hospital admissions than average for comparison weeks and 35% more than expected among patients aged 65 years and older. The majority of this excess (59%) were treatments for dehydration, heat stroke, and heat exhaustion.