MINNESOTAEXTREME HEATTOOLKITM innesota Climate and Health Program
M innesota Depar tment of Health
Environmental Impac ts Analysis Unit

Acknowledgments
The Minnesota Extreme Heat Toolkit was made possible through funding from cooperative agreement 5UE1EH000738
from the Centers for Disease Control and Prevention (CDC) and the commitment of many individuals who contributed
their time and expertise to its development.
The information and resources contained within the toolkit benefited substantially from the input of various local andnational experts. Two specific groups spent considerable time reviewing content and providing expert feedback into
the development of the Extreme Heat Toolkit: the Extreme Heat Training Module Technical Team and the Extreme Heat
Toolkit Steering Committee. We would like to acknowledge and thank the participants who provided advice, resources
and review of the toolkit:
Pam Blixt, Emergency Preparedness Manager, Minneapolis Department of Health and Family Support
Aaron DeVries, Medical Director, Infectious Disease Epidemiology, Prevention, and Control Division, Minnesota
Department of Health (MDH)
Sara Dunlap, Research Analysis Specialist, Site Assessment and Consultation Unit, MDH
Amy Evans, Public Health Emergency Preparedness Coordinator, Olmsted County Public Health Services
Susan Galatowitsch, Professor, Department of Horticultural Science, University of Minnesota
Todd Krause, Warning Coordination Meteorologist, National Weather Service, Chanhassen, MN
Wendy Kvale, Public Health Nurse Consultant, Office of Performance Improvement, MDH
Janice Maine, Principal Planner, Office of Emergency Preparedness, MDH
Geri Maki, Public Health Preparedness Consultant, Office of Emergency Preparedness, MDH
Brenda Menier, Public Health Nurse Consultant, Office of Performance Improvement, MDH
Ighodalo Collins Omondiagbe, Graduate Intern, Environmental Impacts Analysis Unit
Don Sheldrew, Principal Planner, Office of Emergency Preparedness, MDH
Peter Synder, Assistant Professor, Department of Soil, Water, and Climate, University of Minnesota
David Wulff, Business Continuity Coordinator, Office of Emergency Preparedness, MDH
Additionally, we would like to thank the following reviewers from CDC who provided comments on the final draft:
David Hutchins, Environmental Health Scientist, Climate and Health Program
Gino Marinucci, Associate Fellow, Climate and Health Program
Natasha Prudent, Health Scientist, Climate and Health Program
Shubhayu Saha, Senior Fellow, Climate and Health ProgramFor more information contact:
Minnesota Climate and Health Program
Minnesota Department of Health
Environmental Impacts Analysis Unit
625 Robert Street North
PO Box 64975
St. Paul, MN 55164-0975
651-201-4893
health.climatechange@state.mn.us
http://www.health.state.mn.us/divs/climatechange/ii

June 6, 2012

Table of Contents
Acknowledgments									iiTable of Contents									iiiOverview of Extreme Heat Toolkit								ivChapter 1. Introduction to Extreme Heat Events						

1-1Why care about extreme heat events						1-2Minnesota is warming								1-2Defining extreme heat events							1-5Chapter 2. Extreme Heat Events and Public Health						

2-1Health issues caused by extreme heat						2-2Characteristics that increase the risk of heat-related illnesses				2-4Chapter 3. Preparing Minnesota for Extreme Heat Events					

3-1Key steps for planning for and responding to extreme heat events			3-2

Developing a heat response plan							3-4Additional strategies to prevent heat-related illnesses				

3-7

Mitigation/adaptation to extreme heat						3-11
Training and resources for extreme heat						3-11
Chapter 4. Definitions									4-1Chapter 5. References									5-1Chapter 6. Appendices									6-1A. Heat index									A-1B. Categories of medicines that may increase the risk of heat-related illnesses		

B-1

C. Map of Minnesota land cover							C-1D. Draft language for heat response plan/excessive heat annex			

D-1

E. Exteme heat tip sheet for individuals						

E-1F. Data sources for characteristics that increase the risk of heat-related illnesses

F-1

G. Mapping 101: Joining census data for beginning GIS users				G-1

H. Minneapolis case study maps							H-1I. Olmsted County Public Health Services case study					

I-1J. Sample media release								J-1K. Extreme heat resources available online						K-1

iii

Overview of Extreme Heat Toolkit
The purpose of this toolkit is to provide information to local governments and public healthprofessionals about preparing for and responding to extreme heat events. The toolkit is organized
into six interdependent chapters. The first three chapters contain the body of the toolkit, while thelast three chapters include definitions, references and appendices. The first chapter, “Introduction to
Extreme Heat Events,” describes the magnitude of health consequences from extreme heat, changing
weather conditions in Minnesota, and the National Weather Service’s definitions of extreme heat.
The second chapter, “Extreme Heat Events and Public Health,” discusses health illnesses caused byextreme heat and characteristics or risk factors that increase a person’s risk for heat-related illnesses.
The third chapter, “Preparing Minnesota for Extreme Heat Events,” describes key steps in preparing forand responding to an extreme heat event, how to develop a heat response plan, and strategies forpreventing heat-related illnesses and deaths.
The toolkit focuses on Minnesota examples and processes and describes practical, implementablesteps and strategies to prevent morbidity and mortality from extreme heat at the local level. The
toolkit provides several appendices, including a generic heat response plan that can be tailored tomeet the needs of a specific location. The toolkit does not describe comprehensive surveillancesystems for morbidity and mortality from extreme heat because this would most likely occur only in a
few jurisdictions in Minnesota or at the state level.
The goal of the toolkit is to increase Minnesota’s preparedness for extreme heat events, by providing
information and resources to local governments and public health departments to create their own
heat response plan.

iv

Introduction to
Extreme Heat
EventsChapter 1

Extreme heat events can cause a number of health-related problems, including an increase in deaths(mortality) and nonfatal outcomes (morbidity). Yet, almost all of the negative health outcomes fromextreme heat can be prevented by taking appropriate measures to ensure that the public stays cool andhydrated during an extreme heat event. As more counties and cities begin to prepare for extreme heat, it
is hoped that Minnesota will experience fewer heat-related deaths and illnesses.

Why care about extreme heat events?
Although most heat-related deaths and illnesses are preventable, a significant number of people die andsuffer from extreme heat events every year in the U.S. From 1979 to 2003, more people in the U.S. diedfrom extreme heat than from hurricanes, lightning, tornadoes, floods, and earthquakes combined.1 From
1999-2003, about 3,442 deaths resulted from exposure to extreme heat in the U.S.2
The magnitude of deaths and illnesses from extreme heat events is often underreported and little
understood by the general public. Extreme heat events do not typically make the news headlines
compared to other extreme weather events, such as tornadoes and floods, and they do not leave a lasting
trail of infrastructural damage that continuously reminds people of their impact. Therefore, extreme heat
events have been called the “silent killers.”3 However, in recent years there have been several notable heatwaves that have caused a catastrophic number of deaths. In the historic 2003 European heat wave, about
14,800 people in France and about 50,000 people in Europe died from heat-related illnesses.4 In 2010,
Russia experienced a heat wave that caused an estimated 4,824 excess deaths in July in Moscow alone.5
The United Nation News Centre reported that this Russian heat wave caused about 56,000 total fatalities
across the country,6 likely a result of the combination of extreme heat, smog, and smoke from wildfires.7
Closer to home, more than 700 deaths have been attributed to the 1995 Chicago heat wave.8
Extreme heat events occur in Minnesota; however, it is difficult to know the exact number of deaths andillnesses due to extreme heat events because Minnesota does not have an official reporting system fordeaths and illnesses attributable to extreme heat. A review of mortality records for deaths occurring in
the months of May through September indicates that 35 deaths were directly attributable to extreme heatin Minnesota during the years 2000-2010.9 This count likely underestimates the full burden of extreme
heat on mortality, since it only captures deaths in which exposure to excess heat is explicitly listed as acause of death on the death certificate. Because heat-related illnesses can cause various symptoms andexacerbate a wide variety of existing medical conditions, the cause of death can be difficult to establish if
not witnessed by a physician.10 Additionally, this count does not include data from summer 2011 when
Minnesota experienced five separate extreme heat events, one of which broke several records for dew
point temperature. Regarding morbidity, the number of people in Minnesota who have been afflictedwith heat-related illnesses is unknown, but likely to be much higher than mortality numbers.

Minnesota is warming
Minnesota is getting hotter and more humid, which may increase the number of extreme heat events.
Decadal trends assessed by the State Climatology Office, suggest that Minnesota’s average temperature
is increasing and the number of days with a dew point temperature greater than or equal to 70°F is
increasing.

1-2

Extreme Heat Toolkit

Chapter 1

The chart below shows Minnesota’s annual average temperature (red line), which demonstrates thewide fluctuation in temperature from year to year, and the 10-year running average temperature (bluestars) from the late 1890s to 2010. The 10-year running average temperature shows an upward trend intemperature starting in the 1980s.11

There are three significant trends in this overall warming:12
1. Temperature increases vary by season, with winters temperatures rising about twice as
fast as annual average temperatures.
2. Minimum or ‘overnight low’ temperatures have been rising faster than the maximum
temperature.
3. Temperature increases vary by geography. Since the early 1980s, the temperature hasrisen slightly over 1°F in the south of Minnesota to a little over 2°F in much of the north.
Climate change projections developed by various researchers concur with the observed trends. Climate
models project that future temperatures in Minnesota will increase from 2-3°C (3.6-5.4°F) by 2069.13,14
Exact predictions vary with the choice of climate model, assumptions about emission changes, and othermodel parameters. Regardless of these differences, climate model projections have consistently pointed toincreased temperatures in Minnesota in the future.
Also, Minnesota has observed an increasing number of days with high dew point temperatures. The
dew point temperature is the temperature to which the air must be cooled at constant pressure for it tobecome saturated.15 The higher the dew point temperature, the greater the amount of moisture in the air.
Some people may be more familiar with the term ‘relative humidity’ to describe the amount of moisturein the air. Relative humidity is the ratio of the amount of water vapor in the air at a specific temperature
to the maximum amount that the air could hold at that temperature (e.g., dew point temperature),

Minnesota Department of Health

1-3Chapter 1

expressed as a percentage.16 The same amount of water vapor in the air will yield a different percentageof relative humidity if the air temperature changes; whereas, the dew point temperature will stay the samefor the same amount of water vapor. The dew point temperature is always lower than or equal to the airtemperature. When the dew point temperature equals the air temperature, the relative humidity is 100%
(i.e., the air is saturated). During the summer, the dew point temperature, not the relative humidity, isusually a better measure of how humid it feels outside.18
People accustom to continental climates (e.g., Minnesotans and Midwesterners generally) often begin tofeel uncomfortable when the dew point temperature reaches between 65 and 69°F. Most inhabitants ofthese areas will consider dew points above 75 °F extremely uncomfortable or oppressive.18 Higher dew
point temperatures and humidity directly impact people’s health by making it more difficult for people tocool themselves. The human body cools itself through four different mechanisms: radiation, evaporation,
convection and conduction.19 See Chapter 4, “Definitions,” for a description of the four mechanisms.
One of the main cooling mechanisms used during the summer is evaporation. The body perspires andthe perspiration evaporates into the air, cooling the body. When evaporation is inhibited by additional
humidity, perspiration does not evaporate easily off the skin, which reduces the ability of people to coolthemselves.
High dew point and air temperatures combine to create dangerous conditions for human health. The
heat index uses air temperature and relative humidity to determine how humans perceive ambient
temperature. When humidity is high, the air temperature can be lower and still negatively affect humanhealth. For a more detailed description of the heat index and combinations of temperature and humiditythat are harmful to human health, see Appendix A.

Source: Dr. Mark Seeley, Climatologist, University of Minnesota

1-4Extreme Heat Toolkit

Chapter 1

The chart “Twin Cities Annual Number of Days Where Dewpoint Temperatures => 70 degrees F” shows
the trend line (dashed red line) of the number of days where the maximum dew point was greater than orequal to 70°F in the Twin Cities from 1945 to 2010. The slope of the line suggests that the number of days
with a dew point temperature greater than or equal to 70°F may be increasing by 0.53 days per decade.
The dashed blue line suggests that the numbers of days with a dew point at 1800 hours (i.e., 6PM) equal
to or greater than 70°F may be increasing 0.16 days per decade. Dew point temperatures were historicallycollected only at 1800 hours because dew point temperature was collected manually and 1800 hours wasoften the time of day with the highest dew point.
Prior to 2011, the highest dew point temperature ever recorded in the Twin Cities was 81°F on July 30,
1999. On July 19, 2011, the dew point temperature reached 82°F in the Twin Cities.20 On that same day, thestate record dew point temperature was reached in Moorhead, Minnesota with a dew point temperatureof 88°F.21 The only other spot in the Western Hemisphere with a dew point temperature in the 80s that day
was in the Amazon Jungle in South America.
Researchers of a report focusing on predicting climate changes in the Great Lake region ran a global
climate model to estimate temperature extremes in the Great Lakes region through 2100. The climate
model predicted that the number of hot days each summer would increase throughout the period, withmany years during the last few decades of the century likely to experience 40 or more days exceeding 90°F
(32°C).22 The report surmised that the health impacts of increased days with hotter temperatures are likely
to be greatest in urban areas, especially in cities such as such as Minneapolis/St. Paul, where extremely
high temperatures have historically been rare.
Based on observed and predicted trends, extreme heat events have a high probability of occurring more
frequently in Minnesota. Despite the likely increase in extreme heat events, many counties and cities in
Minnesota are not prepared to deal with extreme heat events. Lessening the impact of extreme heat
events requires improving the awareness of public health officials and the general public about the healthrisks of extreme heat events and developing and implementing effective extreme heat notification andresponse plans.

Defining extreme heat events
Extreme heat events are characterized by weather that is substantially hotter and/or more humid than
average for a particular location at a particular time, especially in the spring and summer. Given the
differences between average annual temperatures in St. Paul, Minnesota (45°F), for example, versus theaverage annual temperatures in Atlanta, Georgia (61°F), it is easy to see that an extreme heat event in
Minnesota might not register as an extreme heat event in Georgia.
How hot it feels depends on location, time of year, and the interaction of multiple meteorological variables(e.g., temperature, humidity, cloud cover, wind). Hotter temperatures earlier in the spring are likely to havemore detrimental health impacts than the same temperatures later in the summer because people have
not had time to gradually adjust to the warmer temperatures.23 Definitions of an extreme heat event canshift based on location and time of year. Thus, definitions of an extreme heat event need to be sensitive tothe variables important for a particular location.

Minnesota Department of Health1-5C hapt er 1

Defining an extreme heat event is important for two reasons. First, the National Weather Service (NWS)
needs a definition of extreme heat in order to issue a heat advisory, watch or warning. Second, local
jurisdictions need to define an extreme heat event locally to determine if and when a heat response planshould be implemented. The following section describes the NWS stations that cover Minnesota andhow the NWS defines extreme heat events. Chapter 3, “Preparing Minnesota for Extreme Heat Events,”
describes how local jurisdictions define extreme heat events for the purposes of implementing their
response plan. Timely forecasting of extreme heat events, transferring the forecast information to theagency responsible for the heat response plan and deciding when to implement the response plan are thefirst crucial steps in preventing heat-related morbidity and mortality.
There are six NWS stations serving Minnesota. Each NWS station releases heat advisories, watches, andwarnings depending on the weather in its own service area. Below is a map of the stations.24 Note that insome cases, the NWS station serving Minnesota communities may be located in another state.
The NWS defines extreme heat events differently depending on location. One way the NWS defines anextreme heat event is by using NWS’s current and forecasted weather reports along with site-specific,
weather-based mortality
algorithms to identify extreme
heat conditions. The NWS
Chanhassen office uses the
Synoptic Health Watch-Warning
Network based on work by
Dr. Laurence Kalkstein of the
University of Miami and Dr.
Scott Sheridan of Kent State
University. The network is basedon “evaluating the negative
health impact of oppressive air
masses, as expressed by excess
mortality, in each locality. NWS
forecast data are comparedto historical meteorologicalconditions that have led tosuch mortality increases,
and advisories, watches,
and warnings are indicatedaccordingly.”25 The network
was mainly composed forlarge cities, which are prone toholding onto heat through thenighttime hours, and thus do
not experience a reprieve fromthe heat.

1-6

Extreme Heat Toolkit

Chapter 1

The NWS Chanhassen office issues watches and warnings for Hennepin and Ramsey Counties and will
only issue a watch or warning if both meteorological conditions and the projected mortality data (derived
from the Synoptic Health Watch-Warning Network) indicate an extreme heat event. For other areas of
Minnesota, heat advisories, watches and warnings are issued based on a set of temperature thresholds
over a certain period of time. See Table 1 below for definitions of heat advisories, watches and warnings
for Hennepin and Ramsey Counties and all other counties in Minnesota.

Table 1: Definitions of heat watch, advisory, and warning 1
In Hennepin/Ramsey Counties

Outside Hennepin/
Ramsey Counties

In Hennepin and Ramsey counties aheat watch is defined as: Maximum
heat index at Minneapolis/St. PaulInternational Airport is expected toreach 100°F or greater for 1 day, or
the maximum heat index is expected
to reach 100°F or greater and an
overnight low temperature no cooler
than 75°F for 2 days in a row. In
addition, the Heat Watch/Warning
System must recommend a watch.

Outside Hennepin andRamsey counties a heatwatch is defined as:
Maximum heat index
reaches 105°F or greaterand a minimum heatindex of 75°F or greater
for at least 48 hours.

In Hennepin and Ramsey counties aheat advisory is defined as: Maximum
heat index at Minneapolis/St. PaulInternational Airport is expected toreach 95°F or greater for 1 day, or the
maximum heat index is expected
to reach 95°F or greater and an
overnight low temperature no cooler
than 75°F for 2 days in a row.

Outside Hennepin andRamsey counties a heat
advisory is definedas: Maximum heatindex reaches 100°F
and/or the maximum
temperature reaches
95°F or higher.

In Hennepin and Ramsey counties aheat warning is defined as: Maximum
heat index at Minneapolis/St. PaulInternational Airport reaches 100°F or
greater for at least 1 day. In addition,
the Heat Watch/Warning System, atool develop based on research, must
recommend a warning. A warning
may also be issued if advisory criteria
are expected for 4 days in a row.

Outside Hennepin andRamsey counties a heatwarning is defined as:
Maximum heat index
reaches 105°F or greaterand a minimum heatindex of 75°F or greater
for at least 48 hours.
A warning may also
be issued if advisory
criteria are expected for
4 days in a row.

Excessive Heat Watch
Excessive Heat Watches are issued whenconditions are favorable for an excessive heat
event in the next 12 to 72 hours. A Watch is used
when the risk of a heat wave has increased but
its occurrence and timing is still uncertain. A
watch provides enough lead time so that those
who need to prepare can do so, such as city
officials who have extreme heat response plans.

Heat Advisory
Heat Advisories are issued when an extreme
heat event is expected in the next 48 hours.
These statements are issued when an extreme
heat event is occurring, is imminent, or has avery high probability of occurring. An advisory is
for less serious conditions that cause significant
discomfort or inconvenience and, if caution is
not taken, could lead to a threat to life and/or
property.

Excessive Heat Warning
Excessive Heat Warnings are issued when an
extreme heat event is expected in the next 48
hours. These statements are issued when an
extreme heat event is occurring, is imminent,or has a very high probability of occurring. A
warning is used for conditions posing a threat tolife or property.

1National Weather Service (2012)

Minnesota Department of Health1-7C hapt er 1

Definitions of extreme heat events should be reviewed regularly to ensure that they are and continue
to be applicable to the locality and responsive to actual health impacts. As average temperatures in
Minnesota continue to climb, Minnesotans may start to acclimate to warmer summers. The NWS may
consider revising its heat advisory, watch and warning definitions every few years based on more current
historical meteorological conditions and evidence of heat-attributable adverse health impacts.
Local government staff, public health professionals and other organizations that participate in planning
and/or providing services for preventing heat-related illnesses should identify the NWS station for theirjurisdiction and build relationships with the NWS staff to ensure receiving the most current information
available on predicted extreme heat events.
Minnesota recently broke several heat-related records. During the summer of 2011, there were five heat
episodes in Minnesota that were worthy of issuing heat advisories or warnings. The worst heat event
occurred during the heat wave of July 16-20, 2011. On July 19, a record state dew point temperature
was set in Moorhead at 88°F. The air temperature was 93°F, creating conditions that made it feel likealmost 130°F. On that same day, the Twin Cities experienced an all-time high dew point of 82°F with an
air temperature of 95°F. The combined hot air and high dew point temperatures created a heat index ofalmost 119°F.26

1-8Extreme Heat Toolkit

Extreme Heat
Events andPublic Health

Extreme heat events can cause a range of health problems from relatively minor health issues, such as
C hapt er 2

a heat rash, to life-threatening conditions, such as heat stroke. Extreme heat can aggravate some chronic
diseases and can increase formation of certain air pollutants that can affect people’s health. Everyone
is susceptible to heat-related illnesses, but some people may be more susceptible or ‘at risk‘ for a heatrelated illness because of factors that increase exposure to the extreme heat and/or affect their ability tostay cool. The following chapter reviews heat-related illnesses and the characteristics or risk factors that
increase the risk of experiencing morbidity and/or mortality from extreme heat.

Health issues caused by extreme heat
The body needs to maintain an internal temperature of 98.6°F to function properly. When it is hot outside,
the body becomes challenged to stay cool. When the internal temperature rises, the human body’s ability
to perform critical functions becomes impaired and a person becomes susceptible to serious adverse
health effects.
Extreme heat events can cause a range of health problems from relatively minor health issues, such asa heat rash, to life-threatening conditions, such as heat stroke and ultimately death. Heat exhaustionis the most common heat-related illness.27 Signs and symptoms of heat exhaustion include dizziness,thirst, fatigue, headache, nausea, visual disturbances, weakness, anxiety, confusion, and vomiting.28
Treatment involves monitoring the person in a cool, shady environment and ensuring adequate hydration.
Untreated heat exhaustion can progress to heatstroke, which can be fatal. See Table 2 on pages 2-3 and
2-4 for a list of some of the medical conditions directly attributable to excessive heat exposure along withrecommended responses.
Exposure to extreme heat can aggravate already existing conditions.29 An analysis of hospital admissionsin Chicago during the July 1995 heat wave estimated that the heat wave was responsible for over 1,000
excess hospital admissions, particularly among people with pre-existing diabetes, respiratory illnesses,
and nervous system disorders.30 Another study found that elevated air temperatures were associatedwith short-term increases in cardiovascular-related hospital admissions for 12 US cities.31 For a detailed
description of pre-existing diseases/conditions that can increase the risk of heat-related illnesses anddeaths, see the next section, “Characteristics that increase the risk of heat-related illnesses.”
There is growing evidence that the effects of extreme heat events on mortality are larger during highozone and high particulate matter (PM10) days. Ozone is formed by the reaction of volatile organic
compounds (VOCs) and nitrogen oxide (NOx) in the presence of sunlight and is highly sensitive totemperature.32 Research indicates a strong association between temperatures above 90°F and groundlevel ozone formation.33 Ground-level ozone and high air temperatures have been associated withincreased mortality.34 Ground-level ozone exposure can cause harmful cardiopulmonary health effects,
including lung irritation, breathing difficulties, reduced lung capacity, aggravated asthma, and increased
susceptibility to bronchitis.35 Populations at risk to ozone exposure include outdoor workers in landscapeand construction, and adults and children who are performing strenuous outdoor exercise and play.36
Similarly, during an extreme heat event, mortality is greater on high PM10 days. The interaction of heatdays and PM10 seems to more significantly affect the elderly.37 Exposure to PM can aggravate chronic
respiratory and cardiovascular diseases, and several studies suggest that the elderly and children may beparticularly affected by PM.38
2-2

Extreme Heat Toolkit

Table 2: Heat illnesses and their symptoms 1,2,3
Symptom(s)CausesSafety Tips

• Red cluster of pimples• Blockage of sweat
ducts

Remove the affected person fromheat. Minimize exposure of skinto sun. Keep the affected areadry. Seek medical attention if
rash does not improve.

• Occurs in persons
who are notacclimatized to heat

Elevate and apply compressive
stockings to the affected limbs.

• Blisters• Itching• Red rash on the skin that usuallyoccur on the neck, chest, breast
and/or groin

Heat edema• Swelling in the ankles, feet andhands• Body temperature normal orelevated core temperature up to104° F

Heat tetany• Respiratory problems, such as
breathing difficulty• Muscular problems, including
spasms or numbness or tingling ofmuscles

Chapter 2

MedicalCondition
Heat rash• Increased bloodflow to the skin in
limbs• Hyperventilation• Respiratory
alkalosis

Remove the affected person fromthe heat and advise the person tobreathe slowly.

• Body temperature normal orelevated core temperature up to104° F

Heat cramps• Muscle spasms• Muscles usually affected include
the abdomen, calf, thighs andshoulder muscles• Body temperature normal orelevated core temperature up to104° F

Heat syncope• Dizziness• Fainting• Body temperature normal orelevated core temperature up to104° FHeat
exhaustion• Profuse sweating• Weakness• Rapid breathing• Dizziness• Nausea/vomiting• Muscle cramps• Normal mentation• Body temperature normal orelevated core temperature up to104° F

Minnesota Department of Health• Drinking liquid
without electrolytes• Dehydration• Electrolyte
deficiency

Stop all activities, relocate toa cool location, rest and drink
electrolyte containing fluids. Seek
medical attention if symptoms
persist.

• Increased
blood flow to theskin resulting indecreased bloodflow to the central
nervous system

Lay the affected person gently on
the floor and provide lots of fluid.
Seek medical attention.

• Drinking liquid
without electrolytes

Stop all activities, relocate toa cool location, rest and drink
electrolyte containing fluids. It
can be difficult to determine if
someone has heat stroke andnot exhaustion. If symptoms do
not quickly improve, or unable
to oral rehydrate, seek medical
attention.

• Dehydration• Electrolyte
deficiency

2-3

Heat stroke

C hapt er 2

This is a life
threatening,
adverse effectof exposure to
extreme heat,
usually occuringwhen the bodytemperatureis greater than
104˚F.

• Oral body temperature of 104˚F
and above• Profounddehydration

Call 911 immediately if you see
anyone with these symptoms
and has a body temperature of• Often sudden onset of symptoms • Profound
104˚F and above. While waiting• Confusion or loss of consciousness electrolyte deficiency for first responders, the affected• Body is unable
person should be taken to a cool
• Rapid and strong pulse
to maintain heatshady area. Cool the person with
• Hot, red and dry skindiffusion through the immersion in cool water, spraying
skin
the person with cool water while• Headachefanning
the person vigorously, or• Normal regulation• Dizzinessplacing
ice
packs on neck, axilla,of body temperature• Nausea/vomiting
andgroin.
The
person is unlikely
is no longer intact
to be able tolerate oral fluids.
• Mortality can be as
high as 50%

Centers for Disease Control and Prevention. (2006). Frequently Asked Questions (FAQ) About Extreme Heat. Retreived April 17,
2012, from http://www.bt.cdc.gov/disasters/extremeheat/faq.asp.

1

2

Platt, M. and Vicario, S. (2010). Heat Illness. In Rosen’s Emergency Medicine: Concepts and Clinical Practice, 7th Ed. p1882-3.

Zimmerman JL, Hanania NA. (2005). Chapter 111. Hyperthermia. In: Hall JB, Schmidt GA, Wood LD, eds. Principles of Critical
Care. 3rd ed. New York: McGraw-Hill.
3

In addition to direct health impacts, extreme heat events can result in increased use of energy, power
outages, damage to highways and roads, and an increase strain on the provision of available essential
services like emergency hospital services, ambulance services and security.39 The heat wave that
hit Minnesota in July of 2011 left 750 Excel energy customers without power in the seven-county
metropolitan area and killed livestock throughout the state. “The stress on farm animals caused a die-offworse than some growers have seen in nearly 30 years,” said Byron Hogberg, Farm Services Administration
Director in Renville County in southwestern Minnesota.40

Characteristics that increase the risk of heat-related illnesses
Everyone is susceptible to illnesses due to extreme heat; however, certain characteristics can increase aperson’s risk. Demographic characteristics, social/behavioral factors, and geography/location may affectthe ability of an individual to maintain normal body temperature and stay hydrated. Certain populations
may have more than one characteristic/risk factor that could put them at increased risk. Below is a review
of characteristics that increase the risk of experiencing morbidity and/or mortality from extreme heat.
(For a quick reference of characteristics that increase the risk of heat-related illnesses, see Table 3 on page2-5.) Identification of populations that are more vulnerable to extreme heat events is useful for targeting
limited resources to people who need additional aid during an extreme heat event and an important
strategy for preventing negative health outcomes from extreme heat. For more information on mapping
vulnerable populations and risk factors for extreme heat events, see the Chapter 3, “Preparing Minnesota
for Extreme Heat Events.”

2-4

Extreme Heat Toolkit

Demographic characteristics

Chapter 2

Age-Older adults: Persons 65 years old or older are more vulnerable to negative health outcomes fromextreme heat events than younger adults.41,42 Additionally, the older the person is the greater the risk
for a heat-related illness. A person 75 years old has a greater risk for heat-related illnesses than someone
who is 65 years old. Certain physiological changes associated with aging, especially the body’s decreased
ability to thermoregulate, increase older adults’ risk of experiencing heat-related illnesses.43 Chronic
disease conditions and the use of certain medications also may increase older adults’ susceptibility toadverse health outcomes from heat.44 Elderly persons who live alone and/or at or below the poverty line
are particularly vulnerable to negative health outcomes from extreme heat because of a combinationof factors associated with aging, social isolation, and economic constraints. Older adults are a growing
segment of the population. Using the 2010 census data and estimates from the Minnesota State
Demographers Officer, it is predicted that the number of people 65 years old and older will increase by
91% in Minnesota by 2030.45
Age-Children: Research identifies children, especially children ages five years and younger (including
infants), as being at a greater risk for mortality during hot weather.46,47 Children may be at increased risk
due to dependency on other people for their care and/or physiological differences, including smaller
body mass to surface area ratio than adults, blunted thirst response, production of more metabolic heatper pound of body weight and lower cardiac output.48,49 In the US between 1998 and 2011, an averageof 38 children (five days old to 14 years old) died per year from being left in a motor vehicle during warm
weather. More than half of the deaths are children under two years of age.50 Temperatures in parked cars

Table 3: Characteristics that increase the risk of heat-related illness
Demographic characteristics, social/behavioral factors, and geography/location may
affect the ability of an individual to maintain normal body temperature and stay hydrated.
Demographic characteristics•

Age-Older adults: persons 65 years old or older•

Age-Children: children ages five years and younger (including infants)•

Economic constraints: persons living at or below poverty line•

Persons with pre-existing diseases or mental health conditions•

Persons on certain medications

Social/Behavioral factors•

Social isolation: persons living alone, especially the elderly•

Prolonged exposure to the sun•

Use of alcohol

Geographic/location factors•

Living in urban areas•

Lack of air conditioners•

Living in top floor apartments•

Living in nursing homes/bedridden

Minnesota Department of Health2-5C hapt er 2

can increase quickly even on relatively mild days (i.e., ~ 70°F), especially if the car is parked in the sun.51,52
Leaving the windows slightly open does not significantly decrease the heating rate.53 For a short video
demonstrating how quickly temperatures can increase in a parked car, see the following website: http://
www.nws.noaa.gov/os/heat/index.shtml. Never leave children, infants or pets unattended in a parked
vehicle.
Economic constraints: Several studies have demonstrated increased risk of mortality among people withlow socioeconomic factors.54 Persons living at or below poverty line are less likely to have air conditioners
in their homes,55,56 live in deteriorating and substandard homes,57 and may have difficulty paying for higher
electricity bills from increased electricity usage during an extreme heat event. Persons living at or below
the poverty line might be more concerned about safety and unwilling or unable to seek cooling centersor open doors and windows to increase circulation.58 The homeless are at increased risk for illnesses anddeath due to extreme heat possibly because of limited access to air-conditioned places and underlying
medical conditions.
Persons with pre-existing diseases or mental health conditions: Heat can exacerbate existing conditions,putting certain people at increased risk for heat-related illnesses and possibly death. Any condition that
affects the body’s ability to cool itself or puts additional stress on already compromised systems will
make a person more susceptible to negative health effects from heat. Pre-existing conditions that makea person more vulnerable to extreme heat include obesity;59 cardiovascular disease conditions (e.g.,congestive heart failure, myocardial infarction);60 respiratory disease conditions (e.g., COPD, bronchitis);61,62
neurological diseases;63 endocrine disorders (e.g., diabetes mellitus);64 renal failure; and liver diseases (e.g.,liver cirrhosis). Additionally persons with mental illness or intellectual disabilities are at increased risk fornegative health outcomes due to extreme heat.65,66 They may be unable to make rational decisions thatwould help them recognize symptoms of or limit their exposure to excessive heat.
Persons on certain medications: Persons on certain medications are vulnerable to negative healthconsequences from extreme heat events. Drugs, such as diuretics, anticholinergics, beta blockers andcalcium channel blockers and antipsychotic drugs, make it difficult for the body to dissipate excess heat byinterfering with normal thermoregulatory systems. For a complete list of categories of medicines that may
increase a person’s risk of heat-related illness, see Appendix B.

Social/Behavioral factors
Social isolation: Persons living alone, especially the elderly, are more vulnerable to extreme heat
events.67,68 Socially isolated people may be less likely to recognize the symptoms of excessive heat
exposure, less likely to leave their homes if hot, and/or less willing or able to reach out for help fromothers.
Prolonged exposure to sun: People who are involved in sporting activities or work in outdoor
occupations, like farming, landscaping, roofing, and construction, are at an increased risk for heat-related
illnesses. These people may be exposed to the sun and extreme heat for longer periods of time and needto take extra precautions to stay cool and hydrated.
Use of alcohol: The consumption of alcoholic beverages during extreme heat events increases the riskof heat-related illnesses. Alcoholic beverages can cause dehydration and depress the thermoregulatory
system. In addition, alcohol impairs judgment, influencing a person’s ability to make decisions to limit
exposure to and recognize symptoms of extreme heat exposure.
2-6

Extreme Heat Toolkit

Geographic/location factors

Chapter 2

Living in urban areas: The urban heat island effect is a measurable increase in ambient urban air
temperature and results primarily from the replacement of vegetated land with buildings, roads, and otherheat-absorbing and reflecting infrastructure. Urban dwellers are more at risk for heat-related illnesses
than rural dwellers because of the urban heat island effect. Urban areas are usually hotter and cool off
less at night than rural areas. The annual mean air temperature of a city with 1 million people or more canbe 1.8–5.4°F warmer than its surroundings. In the evening, the difference can be as high as 22°F.69 The
urban heat island effect is proportional to the size of the city, but all cities, large and small experience
the effect. Urban heat islands can increase health risks from extreme heat by increasing the potential
maximum temperatures residents are exposed to and the length of time that they are exposed to elevatedtemperatures.70 According to the 2000 Census, more than half of Minnesota’s population (55%) lives inurban areas.71 For a map illustrating developed places in Minnesota, see Appendix C of Minnesota’s land
cover.
Lack of air conditioners: Living in houses without air conditioning and/or not having access to airconditioned spaces increases the risk of experiencing heat-related illnesses. During periods of extreme
heat, air conditioners regulate and cool indoor air temperatures, putting less strain on the body’s
thermoregulatory system.
Living in top floor apartments: Persons living in top floor apartments are at increased risk of sufferingfrom heat-related illnesses. Hot air rises and is trapped by the roof, so that people who live on the top
floors of a building are exposed to higher temperatures.
Living in nursing homes/bedridden: Persons living in long-term care facilities (e.g., nursing homes,
assisted living, group homes) and/or are bedridden are at increased risk of suffering from heat-related
illnesses. These persons may be at increased risk due to dependency on others for care, and theyfrequently have underlying medical conditions and take medications that affect their ability to regulate
their body temperature.

Minnesota Department of Health2-7Preparing Minnesota
for Extreme Heat
EventsMinnesotan’s are more equipped to deal with snowstorms and the extreme cold than extreme heat.

Extreme heat notification and response plans are critical to preparing Minnesotans for extreme heat
events. Notification systems and plans reflect local conditions and draw upon available local expertiseand resources. As a result, local notification and response plans vary. This chapter discusses the key steps
in responding to an extreme heat event and how to develop a heat response plan. The chapter also
summarizes a range of strategies that can be included in the response plan and used to prevent morbidity
and mortality from extreme heat events.

Chapter 3

Key Steps for Planning for and Responding to an Extreme Heat Event
The key steps for planning for and responding to an extreme heat event have been summarized in Figure
1 on page 3-3. Below is a detailed description of each step.

Step 1: Create a heat response plan
The first step in preparing to respond to an extreme heat event is to develop a heat response plan. A heat
response plan is essential for describing and coordinating activities to prevent heat-related morbidity andmortality. The next section, “Developing a heat response plan,” describes the minimum elements of aneffective response plan. The response plan should define the lead agency responsible for the plan, criteria
for activating the plan, and the roles of agencies and organizations involved with the plan. The plan also
should contain a communications plan, identify high-risk and vulnerable persons, describe strategies toprevent heat-related illnesses and deaths, and establish an evaluation process.

Step 2: Predict extreme heat event and transfer information to lead agency
For successful notification of an upcoming heat event, it is critical for the lead agency of the response
plan (see the next section for a description of the lead agency) to develop partnerships with the NWS toensure early weather forecasts capable of predicting extreme heat conditions a few days in advance of an
extreme heat event. In Minnesota, the NWS provides weather forecasts and determines the issuance ofheat advisories, watches or warnings. Definitions and processes used by the NWS to determine extreme
heat events are described in the section, “Defining extreme heat events.” All Minnesota jurisdictions
involved in planning and implementing heat response plans should develop relationships with theirlocal NWS station to ensure daily monitoring of weather conditions and early detection and transfer of
information regarding the characteristics of the upcoming event to the lead agency of the response plan.

Step 3: Assess risk and determine activation of response plan
Once the lead agency is informed of a possible extreme heat event, the agency, in collaboration with
its partners, needs to determine if the characteristics are indicative of an extreme heat event that could
trigger activation of the heat response plan. Generally, the lead agency reviews the NWS forecast data andhealth-impact information to determine whether location-specific criteria for an extreme heat event aresatisfied, and then, if the conditions are met, the agency activates the plan. Activation of the heat response
plan should happen before the extreme heat event occurs to ensure that preventive measures andstrategies are implemented at the most opportune time for preventing illnesses and deaths from extreme
heat.

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Extreme Heat Toolkit

Figure 1: Key Steps for Responding to an Extreme Heat Event*

1. A heat response plan should be developed before an extreme heat event. Below
are the critical elements of a successful response plan.
Response Plan Elements:

Chapter 3• Identification of a lead agency responsible for the response plan
• Defined criteria for activating and deactivating the plan
• Defined roles and activities of agencies and organization involved with the plan
• A communications plan for communicating heat-related information to partners and the public before
and during an extreme heat event• Identification of vulnerable persons• Strategies for preventing morbidity and mortality from extreme heat
• Evaluation of the response plan

2. Predict extreme heat event• NWS forecasts weather conditionsof a probable extreme heat event• NWS provides characteristics of theevent to the lead agency

3. Assess risk and determine

6. Evaluate response plan

activation of response plan

• Lead agency, in collaboration with its
partners, reviews and evaluates data collectedduring the event and lessons learned
and updates the response plan
accordingly• Lead agency, in collaboration with NWS
and its partners, reviews activation criteria
based on predicted meteorologicalcharacteristics and health impacts
and determines activation of
the response plan

Extreme Heat
Event
5. Implement response plan
• Lead agency, in collaboration with its
partners, implements strategies
within the response plan

4. Activate response
plan and notify the public• If established criteria are met, lead agency
activates the response plan
• Lead agency supports notification of
the public and provides information onvulnerable populations and strategies on
how to prevent and recognize
heat-related illnesses* Although this diagram presents key steps in responding to an extreme heat event as discrete steps, actual details andtiming of each step will vary locally. For example, determining the activation of the response plan may happen
simultaneously with notifying the public of an impending extreme heat event. The response plan should reflect local
conditions and resources and should clearly articulate each step in responding to an extreme heat event, along with theagencies and organizations that are responsible for implementing each step of the process.

Minnesota Department of Health3-3Step 4: Activate response plan and notify the public

C hapt er 3

Assuming the impending heat event meets location-specific criteria for an extreme heat event, the leadagency activates the response plan. Immediately after a decision has been made to activate the extreme
heat response plan, the public needs to be informed of the timing, severity and duration of the forecasted
extreme heat event. Effective public notification of an upcoming extreme heat event helps eliminate
the risk of the heat event taking a population by surprise. Notifying the public of anticipated conditions,strategies to stay cool and hydrated, and places to go to cool off will enable residents to prepare
themselves and will enable the organizations involved in the response to concentrate on known high-risk
individuals and locations. Advance public notification about the cooling centers (if used as a strategy)
will increase the likelihood that at-risk individuals can take advantage of these services. All messages
regarding an upcoming extreme heat event should be coordinated with media outlets to ensure thepublic receives consistent and accurate information. The communications strategy should be described indetail within the heat response plan.

Step 5: Implement response plan
The fifth step in responding to an extreme heat event is to implement the strategies in the response plan.
The strategies should reflect the demographics and vulnerabilities of the community. See the next two
sections for detailed descriptions of several strategies that can be inserted into the response plan. The
response plan should clearly delineate which participating agencies and organizations are responsible for
implementing each strategy.

Step 6: Evaluate response plan
Each step of responding to an extreme heat event should be reviewed and evaluated after an extreme
heat event. Evaluation is critical for improving the plan and making it more effective for preventing heatrelated illnesses and deaths in the future.

Developing a heat response plan
Heat response plans have been shown to be effective in reducing heat-related mortality.72 Heat responseplans describe in detail the roles and actions of government agencies and nongovernmental organizations
for preventing morbidity and mortality from an extreme heat event. Each city or county in Minnesota
should have a heat response plan. The level of detail and the number of strategies in the plan will vary
based on available resources, geographic location, agencies and organizations involved in planning andresponding, and the types and distribution of vulnerable populations. For a draft heat response plan thatcan be modified and adapted to a local jurisdiction, see Appendix D.

All Response Plans Should Contain the following Elements:73
Lead agency: A lead agency for implementing the extreme heat response plan should be identified.
Typically, a health department or emergency management is the lead agency in charge of responding to
extreme heat events, but this can vary at the local level. The lead agency will activate the plan and help
coordinate the efforts of organizations involved in the response.

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Extreme Heat Toolkit

Criteria for activating and deactivating the plan: Criteria for activating and deactivating an extreme heat
response plan vary and should be based on location-specific factors that affect the relationship between
weather and mortality. These factors may include air temperatures, dew point temperatures, wind,daytime highs and overnight lows, and how long the hot weather is expected to last. Some public healthdepartments have their own thresholds and calculations that include health-related criteria for extreme
heat events. Others use the NWS criteria for activation. See the box below for how the City of Minneapolis
determines activation of their heat response plan.

Chapter 3

Minneapolis Department of Health and Family Support Activationof Heat Response Plan
The Minneapolis Department of Health and Family Support reviews information from the
Synoptic Health Watch-Warning Network to assess the health risks for an upcoming heat
event. The integrated heat health watch/warning system uses meteorological forecast data
as inputs into a health impact model. The program identifies when forecast conditions may
result in excess mortality and estimates the potential number of heat-attributable deaths. This
information is used by Minneapolis to determine activation of the heat response plan and thetype and scope of response activities that will be implemented.
Roles and activities of agencies and organization involved with the plan: Implementation of aheat response plan requires close collaboration between government agencies (e.g., local publichealth department, city/county emergency management, NWS, tribal health departments) and nongovernmental organizations, especially organizations that serve the community and vulnerable
populations (e.g., the American Red Cross, Meals on Wheels, Salvation Army). Engaging local organizations
that work with vulnerable populations in planning and implementing the response plan will make iteasier to identify appropriate strategies for the vulnerable populations in the community. Additionally,
these organizations are most likely to perform successful outreach and strategies targeted to specificpopulations. The plan must clearly articulate the roles and responsibilities of all the organizations involvedin the plan.
Communications plan: The communications plan needs to articulate communication strategies
both between partners involved in the response plan and with the public. There should be frequent
communication between the NWS, the lead agency in charge of the response plan and other collaborating
agencies and organizations. Additionally, the plan should identify communication strategies forcommunicating heat-related information before and during an extreme heat event. For example, thelead response agency, in coordination with other partner organizations, should coordinate extreme heat
education/awareness campaigns in their communities in the spring before a heat event to help prepare
and educate residents of the dangers of extreme heat.
In addition to messages to the public, information should be provided to organizations/companies thathave at-risk populations (e.g., young children, outdoor workers, elderly) and may include the following:
schools, daycares, landscape/construction businesses, sports teams/camps, and senior living facilities.
Messages should include information on what to do (e.g., how to prevent illnesses from extreme heat) (seeAppendix E for a tip sheet), symptoms of heat-related illnesses (see Table 2 on page 2-3), characteristics
of persons more vulnerable to extreme heat (see Table 3 on page 2-5), and where to go for more
information. Messages may be transmitted through a variety of media outlets, including television, radio,

Minnesota Department of Health3-5internet, and distribution of fliers and posters. Messages should be tailored, translated and sensitive tothe demographics and population of the area. For example, translations of tip sheets for individuals could
be translated into the top five languages spoken in Minnesota, in addition to English, which are Spanish,
Hmong, Somali, German and Vietnamese.74 The communications plan should be developed before theheat event and updated after the event using lessons learned from implementing the plan.

C hapt er 3

Identification of vulnerable persons: Quantifying and mapping vulnerable populations and other risk
factors provide important information for planning and implementing appropriate strategies that reachthe most vulnerable members of a community. The lead response agency or another entity should create
data summaries and/or maps to identify the most vulnerable populations in their community and where
the populations reside, so that appropriate preventative actions and strategies for these populations canbe determined before an extreme heat event. See the section, “Characteristics that increase the risk ofheat-related illnesses,” for more information on characteristics to map.
MDH created a suite of resources to aid local public health departments in locating their community’svulnerable populations. The suite includes the following resources:
1. Statewide maps of fivevulnerability characteristics:
a. Percent of population
65 years old and olderb. Percent of population
less than 5 years oldc. Percent of population
65 years old and older
living alone (see image
on the right)
d. Percent of population
living below thepoverty levele. Percent of population
living below 200% of
the poverty level.
These maps can be found online with an
Excel spreadsheet that contains tabulated
data at: http://www.health.state.mn.us/
divs/climatechange/extremeheat.html.
The data described in the state maps areat the county subdivision level (e.g., city,
township, or unorganized territory).
2. A list of data sources forvulnerable populations and risk
factors identified in the section“Characteristics that increase
the risk of heat-related illnesses.”
The list links the characteristics
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Extreme Heat Toolkit

to appropriate data sources. Two types of data sources are referenced in the list: a source that
contains summarized/tabulated data at the county level, and another source that contains raw
data for lead agencies that may want to create maps or summaries at smaller geographic levels,
such as cities or census tracts. The list of data sources can be found in Appendix F.

Chapter 3

3. A GIS primer that describes how to use GIS to create maps of vulnerable populations and risk
factors. This resource has been developed for local public health professionals and planners whoalready have some knowledge of ArcGIS software. It walks users through the process of joining
data to shapefiles and how to display the joined data using quintiles. The primer on mapping
vulnerable populations and certain risk factors can be found in Appendix G.
In 2011, MDH worked with the Minneapolis Department of Health and Family Support to develop a setof maps to help identify vulnerable populations and environmental characteristics that could aid with
implementing strategies to prevent heat-related morbidity and mortality. The set of maps can be foundin Appendix H. The partnership helped identify additional factors that are important for planning for
extreme heat events, including mapping the locations of public air-conditioned buildings, the percentageof residential units with central air-conditioning, special residential buildings such as nursing homes
and group homes, and impervious surfaces within the community. In one instance, by geographically
identifying where cooling centers/cool buildings are located and comparing those locations with where
vulnerable populations reside, public health staff were able to identify places that needed additional
resources and were able to site cooling centers or other resources in places that were easily accessible tothe at risk populations. The Minneapolis maps are meant to provide an example of some of the additional
types of characteristics that may be helpful to review when planning for an extreme heat event. Local
jurisdictions may discover other important characteristics to map as they develop the best strategies fortheir community.
Evaluation: Response plans should be reviewed and evaluated after an extreme heat event. Modifications
to the plan should address lessons learned and changes in local conditions. This ensures continuous
quality improvement and rectifies any challenges or mistakes observed from implementing the plan
during previous events. The agencies and organizations involved in responding to the extreme heat
events should partake in the evaluation process. Records on heat-related morbidity and mortality that
occurred during the extreme heat event also should be collected, analyzed and used to adjust strategies
and/or criteria for activating the heat response plan.

Additional strategies to prevent heat-related illnesses
In addition to those essential elements described above, there are more strategies that may be included
in a local heat response plan. Not all of the following strategies will be feasible or appropriate for every
location. The best strategies for any given jurisdiction utilize local resources and are tailored to the at-risk
populations within the community. For a listing of some of the strategies that have been implemented in
Minnesota, see Table 4 on page 3-10, which provides a checklist of response plan elements and strategies
and demonstrates activities performed by Olmsted County Public Health Services and the Minneapolis
Department of Health and Family Support to prevent morbidity and mortality from extreme heat. Fora detailed case study of strategies and lessons learned by Olmsted County Public Health Services, see
Appendix I.

Minnesota Department of Health3-7Coordinate distribution of information on heat exposure symptoms and tips on how to stay cool for
public broadcasts: Educating the public and communicating prevention information to them before andduring an extreme heat event is critical to reducing illnesses and deaths due to extreme heat exposure.
Publicly broadcasting cooling tips and symptoms of excessive heat exposure should complement
broadcasts about the extreme heat conditions and help residents respond to the heat appropriately (e.g.,
stay well-hydrated, seek air-conditioned locations, minimize direct sun exposure). See Appendix J for asample press release. A tip sheet for staying cool can be found in Appendix E.

Chapter 3

Disseminate information related to preventing heat-related illnesses to community organizations andfacilities with concentrations of high-risk individuals: Developing a database/list of facilities (e.g., thosewith mobility/health impaired residents) and organizations that serve vulnerable populations and theirlocations aids prioritization of prevention efforts to populations vulnerable to extreme heat and facilitates
dissemination of extreme heat information to the organizations that serve these populations throughfaxes, emails, and/or telephone contact trees. For example, nursing homes and senior living centers thatmight not have air conditioning should be contacted and provided information to ensure that their
populations are staying cool and are being assessed for symptoms of overexposure to heat.
Activate a heat line: An emergency heat line provides real-time advice and information during extreme
heat events that can help prevent heat-related illnesses. A heat line can be activated when the response
plan is activated or heat-related messages can be incorporated into more general, full-time systems (e.g.,
211 line). In much of Minnesota, the United Way supports a 211 line that provides information to people
during an extreme heat event. The Minneapolis Department of Health and Family Support utilizes thecity’s 311 information line to disseminate heat event information and track the number of calls coming in
related to extreme heat issues. Monitoring heat line calls and 911 calls made during an extreme heat event
can provide information about how well the community is adapting to the heat. A reverse 911 call system
can be activated, so that numbers that call 911 during an extreme heat event can be dialed and notified ofcurrent information on weather forecasts and safety measures.
Identity and designate buildings with air conditioning as public cooling centers and extend hours ofoperation: Spending time in an air-conditioned building during an extreme heat event is one of the mosteffective means of reducing a person’s risk of developing a heat-related illness. Work with partners to
identify and designate specific public or private buildings with air conditioning as official cooling centers.
If possible choose buildings with back-up generators for cooling centers. Cooling centers should be ADA
accessible and monitored by appropriate staff. Information on providing full access to a cooling center canbe found in Chapter 7 of the ADA Best Practices Tool Kit for State and Local Governments, available online at:
http://www.ada.gov/pcatoolkit/toolkitmain.htm. Extending the hours of operation of the cooling centers
increases the opportunity for high-risk individuals to spend time in an air-conditioned environment.
Providing free public transportation to cooling centers helps individuals who may have limited access totransportation and financial resources to reach the center.
Work with the public and private sector to allow public gathering at buildings with air conditioning
and extend hours of operation: Minnesota has had varying degrees of success with opening public
cooling centers. See Appendix I for a description of Olmsted County Public Health Services experience
with providing cooling centers. Allowing the public to congregate freely at air-conditioned places where
they already frequent, such as shopping malls, libraries and movie theaters, can increase the use of airconditioned buildings and minimize negative health impacts. Agreements should be made with theowners of these buildings before announcements are made to the public about visiting the facilities. Many
3-8

Extreme Heat Toolkit

of the people who are at greatest risk for negative health effects from an extreme heat event may regularly
visit specific air-conditioned locations and may be more likely to go to these places versus a cooling
center. Hours of operation of public spaces, such as libraries and public swimming pool, may be extended
to increase accessibility for working families. Providing free public transportation to cool places during
an extreme heat event helps individuals who may have limited access to transportation and financial
resources to reach a cool destination.

Chapter 3

Outreach to vulnerable populations: Some high-risk individuals (e.g., elderly living alone, homelesspersons) need to be contacted directly, and, preferably, observed several times a day during an extreme
heat event to ensure that cooling tips are being followed (e.g., fluids are being consumed, appropriate
clothing is being worn) and that any symptoms of overexposure are recognized and alleviated as earlyas possible. Depending on local resources, persons involved in the outreach process can include thefollowing: social and health workers, volunteers, church organizations, other nongovernmental agencies,
and the police. Additional efforts must be made to outreach and evaluate the homeless. Increased
outreach efforts should be supported by authorizing officials to move individuals believed to beexperiencing medical difficulties or at extreme risk to cooling shelters for observation and treatment.75
Arrange for extra staffing of emergency support services: Extreme heat events place additional burdens
on emergency medical and social support services through increased use of these services. Increasing
staffing helps avert any crises that may arise from the systems becoming overwhelmed. Hospitaladministrators should be encouraged to prepare for increased patient loads during extreme heat events.
Suspend utility shutoffs and provide transportation and financial assistance: Local governments should
develop partnerships and/or policies to prevent power and water companies from shutting off services
to their customers due to nonpayment of bills during extreme heat events. Drinking water, taking coolbaths/showers and using air conditioners are some of the most effective ways of preventing heat-related
morbidity and mortality. Free bus passes and/or other subsidized means of transportation to cooling
centers also should be provided to low-income people. Vouchers for buying air conditioners and financial
aid for electricity bills are other ways of providing assistance to low-income people.
Provide water at public places: Providing sources of clean potable drinking water at strategic locations inpublic places (e.g., parks, malls and cooling centers) enhances people’s ability to stay hydrated.
Reschedule outdoor public events when possible: Developing and implementing policies that identify
when large outdoor events or activities (e.g., sports games, outdoor camps, concerts) should be canceledor rescheduled due to extreme heat can help prevent heat-related illnesses. To the extent that local
officials can control these events (e.g., through permits or use of facilities), efforts should be taken toreschedule an event or, when rescheduling is not feasible, require water stations, medical staff and/or “coolzones” for attendees.
Provide information to pet owners on protecting their pets from extreme heat: Some pet owners are
reluctant to leave their homes to go to a cool place if they cannot bring their pets with them. Providing
messages to pet owners on tips for keeping their pet cool and hydrated can help to alleviate their anxiety.
Also, pet owners can be encouraged to call their veterinarian if they have any specific concerns. If possible,
identify a local cool place that may be willing to accept people and their pets.

Minnesota Department of Health

3-9Table 4: Checklist of response plan elements and strategies
implemented by Olmsted County and the City of Minneapolis
Strategies

Olmsted County

City of Minneapolis

i
i
i

i
i
i

Response Plan Elements1
Lead agency responsible for the response plan
Criteria for activating and deactivating the plan

C hapt er 3

Assigned roles and activities of agencies and organization
involved with the planCommunications plan for communicating heat-related
information to partners and the public before and during an
extreme heat event
Identification of vulnerable persons

i
i
i

i
i

i

i

Establish partnership with local National Weather Service(NWS) station to ensure access to weather forecasts capable ofpredicting extreme heat conditions a few days in advance of an
event

i

i

Ensure timely transfer of weather forecasts to lead agencyii

Review activation criteria based on predicted meteorologicalcharacteristics and health impacts and determine activation of
the response planii

Coordinate distribution of information about the anticipatedtiming, severity, and duration of extreme heat event; heat
exposure symptoms; and tips on how to stay cool during an
extreme heat event for public broadcasts

i

i

i

i

i

i
i

Strategies for preventing morbidity and mortality from extreme
heat (see below)
Evaluation of the response plan

Response Plan Strategies
Prediction

Assessment, Activation and Notification

Implementation
Disseminate information related to preventing heat-related
illnesses to community organizations and facilities withconcentrations of high-risk individuals
Activate a heat line
Identify and designate buildings with air conditioning as public
cooling centers and extend hours of operation
Work with the public and private sector to allow publicgathering at buildings with air conditioning and extend hoursof operation
Outreach to vulnerable populations
Arrange for extra staffing of emergency support services

i
i

i
i

Table and strategies adapted from U.S. Environmental Protection Agency. 2006. Excessive heat events guidebook.
www.epa.gov/heatisland/about/heatguidebook.html.

1

3-10

Extreme Heat Toolkit

Response Plan Strategies (cont.)
Suspend utility shutoffs and provide transportation andfinancial assistance

i

i

i

i

i

i

Provide water at public places
Reschedule outdoor public events when possible
Provide information to pet owners on protecting their petsfrom extreme heat
Prepare strategies for a power outage

Chapter 3

Evaluation
Evaluate heat response plan after implementation

Mitigation
Support and promote programs and policies to reduce effects
of urban heat islands

Prepare strategies for a power outage: If a wide-spread power outage occurs during an extreme heat event,
air conditioning may be unavailable. Ideally, messages regarding tips on how to stay cool and hydrated havealready been provided to the public and vulnerable populations. People who do not want to leave theirhomes and are without air conditioning should be encouraged to drink plenty of water and take cold bathsor showers to cool off. Buildings where vulnerable populations reside, such as hospitals, nursing homes,
etc. may want to consider buying a back-up generator to ensure that their building will stay cool if there is a
power outage.

Mitigation/adaptation to extreme heat
It is important to support and promote programs and policies to reduce effects of urban heat islands.
Although strategies to reduce the urban heat island effect typically are not included within a responseplan, they are important for long-term adaptation to climate changes and to help reduce the severity andduration of urban residents’ exposure to high-heat conditions.76 Programs and policies that increase urban
vegetation, especially shade trees, and encourage the use of cool building materials can help reduce theurban heat island effect. Some strategies that help reduce the urban heat island effect can provide multiple
health benefits. For example, green roofs can help reduce the urban heat island effect, can help capture andclean stormwater, and can provide a green space for mental health benefits for people in the city.

Training and resources for extreme heat
MDH created a training module on extreme heat and public health for local government staff and publichealth practitioners. The training module provides a basic overview of extreme heat and its impacts on
public health and contains some of the information within this document. The training was created as aPowerPoint presentation with detailed notes so that professionals could use the presentation to train others
on extreme heat and public health. A copy of the presentation with detailed notes can be found on the MDH
website at: http://www.health.state.mn.us/divs/climatechange/extremeheat.html.
MDH developed a list of links to additional online resources. Appendix K provides a listing and brief
description of several websites that contain additional information on extreme heat events.

Minnesota Department of Health

3-11Definitions

Below are definitions of words, phrases and terminology used within the Minnesota Extreme Heat

Toolkit. It is important to note that some of the below definitions may differ outside the context of thistoolkit. The definitions below clarify the usage of these words within the toolkit.

At risk
People who are “at risk” are people who are at an increased risk for heat-related illnesses because they
have certain risk factors, e.g., young children, people with pre-existing conditions or diseases.

Extreme heat event

Chapter 4

An extreme heat event is a period of time with abnormally high air temperatures and/or high dew pointtemperatures that affect human health. An exact definition of an extreme heat event varies by geographic
location.

Extreme heat response plan/excessive heat annex
A plan/annex for states, communities, governments, etc. to use in the event of an extreme heat event andcontains information on strategies for preventing heat-related illnesses and identifies who will perform thestrategies.
Modified from: http://www.getreadyforflu.org/pg_glossary.htm

Risk factor
A risk factor is a characteristic that is statistically associated with, although not necessarily causally related
to, an increased risk of morbidity (i.e., illness, disease, or condition) or mortality (i.e., death). For example,
age is a risk factor for heat-related illnesses.
Modified from: http://dictionary.webmd.com/terms/risk-factor

Vulnerable population
Subpopulations who are at increased risk of heat-related illnesses because they have certain risk factors.
Modified from: http://www.hc-sc.gc.ca/dhp-mps/homologation-licensing/gloss/index-eng.php

Ways the human body loses heat
The human body loses heat in four different ways:1
1. Radiation – transfer of heat through electromagnetic waves (i.e., the body releases heat simply by
being in an environment cooler than the body temperature). This is similar to heat leaving a woodstove.
Radiation is a normal process of heat moving away from the body when air temperatures are lower than
68°F. 2

Platt M and Vicario S. (2010). Heat Illness in Rosen’s Emergency Medicine: Concepts and Clinical Practice, 7th Ed.
p1882-3.
1

4-2

Extreme Heat Toolkit

2. Evaporation – conversion of liquid into a gas, which transfers heat energy to the gas and away from theskin (i.e., the body sweats and the evaporation of the sweat from the skin cools the body). During intense
exercise, the body loses 85% of its heat through sweating.2
3. Convection – direct transfer of heat to water vapor molecules surrounding the skin. Heat is carried anddispersed from the body due to fluid motion. This is similar to sitting in front of a fan.2
4. Conduction – transfer of heat to air or water surrounding our bodies. Heat is lost when temperatures arelower than 68°F. This is heat lost from sleeping on the cold ground or when the body is submerged in water.
Water causes more heat loss than air, so heat can be lost from the body very quickly when it is placed in cold
water.2

Chapter 4

As air temperature and humidity increases, the ability to cool the body through radiation is dramaticallyreduced. Under direct sunlight, heat is actually transferred back to the skin, reversing the process of heattransfer and warming the body. As air temperature rises, evaporation becomes the dominant mechanismof heat transfer through sweating; however as humidity increases, the ability to transfer heat and cool the
body through evaporation is dramatically reduced. Convection is minimal when there is little movementin the air around the skin but can become more important as wind speed increases. Convection does notcool the body when air temperatures are high. Only 2% of our body heat is lost through conduction whensurrounded by air; however, heat loss through conduction in water can be 25 times greater.

Healthwise. (2011). WebMD: First Aid & Emergencies: Ways in Which the Body Loses Heat. Available online: http://
firstaid.webmd.com/ways-in-which-the-body-loses-heat. Accessed April 16, 2012.

2

Minnesota Department of Health4-3

References

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34

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35

Bernard SM, Samet JM, Grambsch A, Ebi KL, Romieu I. (2001). The potential impacts of climate variability andchange on air pollution-related health effects in the United States. Environmental Health Perspectives Vol 109,
Supplement 2, pp 199-209.

36

World Health Organization (WHO) Europe. (2009). Improving public health responses to extreme weather/heat-waves – EuroHEAT: Technical summary. Available online: http://www.euro.who.int/__data/assets/pdf_
file/0010/95914/E92474.pdf.

37

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64

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75

76

Luber, G & McGeehin. (2008). Climate Change and Extreme Heat Events. Am J Prev Med 2008:35(5).

Minnesota Department of Health5-5Minnesota Department of Health625 Robert Street North
PO Box 64975
St. Paul, MN 55164-0975
651-201-4893
health.climatechange@state.mn.us
http://www.health.state.mn.us/divs/climatechange/

June 2012