Excessive Heat 

Events Guidebook

EPA 430-B-06-005 | June 2006

United States Environmental Protection Agency

Office of Atmospheric Programs (6207J)

1200 Pennsylvania Avenue NW, Washington, DC 20460
How to obtain copies

You can electronically download this 

document from EPA’s Heat Island Site at 

http://www.epa.gov/heatisland/about/

heatresponseprograms.html. To request 

free copies of this report, call the National 

Service Center for Environmental 

Publications (NSCEP) at 1-800-490-9198.

For further information

For further information, contact Jason 

Samenow, 202-343-9327, samenow.jason@

epa.gov, U.S. Environmental Protection 

Agency.
United States Environmental Protection Agency

Office of Atmospheric Programs (6207J)

1200 Pennsylvania Avenue NW, Washington, DC 20460

Excessive Heat 

Events Guidebook

EPA 430-B-06-005 | June 2006
Excessive Heat Events Guidebook

Table of Contents

Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

List of Acronyms and Abbreviations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3

Summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5

Chapter 1 Overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.1 Why Care about EHEs?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.2 Guidebook Goals. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7

1.3 Guidebook Development. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8

Chapter 2 EHE Health Impacts and Risk Sources . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.1 Defining an EHE. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 9

2.2 Health Risks Attributable to EHE Conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10

2.3 Quantifying the Health Impacts of EHEs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 11

2.3.1 EHEs and U.S. mortality. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12

2.3.2 EHEs and U.S. morbidity. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 14

2.4 Identifying Characteristics that Affect EHE Health Risks. . . . . . . . . . . . . . . . . . . . . . . 16

2.4.1 Meteorological conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 16

2.4.2 Demographic sensitivities. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2.4.3 Behavioral choices. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17

2.4.4 Regional factors. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 18

Chapter 3 Summary of Current EHE Notification and Response Programs . . . . 21

3.1 Elements in Select EHE Programs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21

3.1.1 EHE prediction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

3.1.2 EHE risk assessment. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23

3.1.3 EHE notification and response. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24

3.1.4 EHE mitigation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

3.2 Case Studies in the Development and Implementation of EHE Programs. . . . . . . . 26

3.2.1 Philadelphia. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26

3.2.2 Toronto. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 30

3.2.3 Phoenix. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 32

3.3 Evidence on the Performance of EHE Programs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 33
Table of Contents

Chapter 4 Recommendations for EHE Notification and Response Programs . . 35

4.1 EHE Definition and Forecasting. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

4.1.1 EHE criteria must reflect local conditions. . . . . . . . . . . . . . . . . . . . . . . . . . . . 35

4.1.2 Ensure access to timely meteorological forecasts. . . . . . . . . . . . . . . . . . . . . . . 36

4.2 Public Education and Awareness of EHE Risk Factors and Health Impacts. . . . . . . . 36

4.2.1 Increase and improve EHE notification and public education. . . . . . . . . . . 36

4.2.2 Provide information on proper use of portable electric fans 

during EHEs. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37

4.3 EHE Response Preparation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 38

4.3.1 Develop a clear plan of action identifying roles and responsibilities. . . . . . . 38

4.3.2 Develop long-term urban planning programs to minimize heat 

island formation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

4.4 EHE Response Actions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 39

4.5 Review EHE Programs to Address Changing Needs, Opportunities, 

and Constraints. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 41

References . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 43

Appendix A: Excessive Heat Event Resources Available on the Internet . . . . . . . . 47

Appendix B: Use of Portable Electric Fans during Excessive Heat Events . . . . . . . 49

Appendix C: Excessive Heat Events Guidebook in Brief . . . . . . . . . . . . . . . . . . . . . . . 51
Excessive Heat Events Guidebook
Acknowledgments

Acknowledgments 

The primary agencies that partnered to support this guidebook’s development are 

the U.S. Environmental Protection Agency (EPA), the Centers for Disease Control and 

Prevention (CDC), the National Oceanic and Atmospheric Administration’s (NOAA’s) 

National Weather Service (NWS), and the U.S. Department of Homeland Security (DHS).

This guidebook reflects the commitment of individuals who contributed their time and 

expertise to guide its development while evaluating a wide range of information. The 

key contacts at each of the partnering agencies were instrumental in the guidebook’s 

development. Alan Perrin and Jason Samenow of EPA served as the guidebook’s 

day-to-day project managers from its conceptualization through production. Jannie 

Ferrell and Mark Tew of NOAA’s NWS, George Luber and Mike McGeehin of CDC, 

and Carl Adrianopoli of DHS similarly served as the principal guidebook contacts 

at their respective agencies, facilitating access to the respective staff and resources of 

those agencies. David Mills of Stratus Consulting managed the guidebook’s technical 

development as the primary EPA consultant. He was greatly assisted in this work by 

Dr. Laurence Kalkstein of Applied Climatologists Inc. and the University of Delaware 

Center for Climatic Research. Dr. Kalkstein helped pioneer, and continues to lead, the 

development of integrated meteorological and human health models for forecasting 

excessive heat event (EHE) conditions. He also contributed a wealth of background 

information in the form of published articles about and insight into forecasting EHEs, 

quantifying their health impacts, and coordinating the development of EHE watch/

warning systems. 

Ultimately, though, this guidebook could not have been developed without the 

involvement of the members of the Technical Working Group (TWG) that was assembled 

to help identify and summarize essential information and to comment on drafts of the 

guidebook. Their collective experience designing, implementing, supporting, operating, 

and evaluating EHE notification and response programs throughout the United States and 

Canada was an invaluable resource. The members of the TWG are as follows:

Nancy Day and Marco Vittiglio, Toronto Public Health

Timothy Burroughs, Nikolaas Dietsch, Anne Grambsch, and Kathy Sykes, EPA

Tony Haffer, Melinda Hinojosa, and Paul Trotter, NOAA/NWS

Jerry Libby (retired) and Lawrence Robinson, City of Philadelphia Department of 

Public Health

Christopher Payne, Cincinnati Health Commissioner’s Office

Liz Robinson, Energy Coordinating Agency of Philadelphia.

The TWG’s guidance and perspective make this guidebook such a potentially useful 

resource. The members’ enthusiasm and commitment of time to the guidebook’s 

development are deeply appreciated by the partnering agencies and those involved with 

the guidebook’s technical development. 
Excessive Heat Events Guidebook

Finally, extremely helpful comments were received on a final draft of the guidebook from 

colleagues and researchers contacted by members of the TWG. In addition to staff at the 

partnering agencies, these reviewers included: 

Pamela Blixt, City of Minneapolis Emergency Preparedness Coordinator; Robert Davis and 

Chip Knappenberger, New Hope Environmental Services; Kristie Ebi, Exponent Inc.; 

Pat Finnegan, Metropolitan Chicago Healthcare Council; Robert French and Warren Leek, 

Maricopa County; Stephen Keach, Perrin Quarles Associates; Sari Kovats, London School of 

Hygiene and Tropical Medicine; Marc Rosenthal, Yale University; Jonathan Skindlov, 

Salt River Project Water Resource Operations; Steven Wallace, University of California, 

Los Angeles Center for Health Policy Research; and Scott Wright, University of Utah.
Acronyms and Abbreviations

List of Acronyms and Abbreviations

CDC Centers for Disease Control and Prevention

CSA Canadian Standards Approved

DHS U.S. Department of Homeland Security

EHE excessive heat event 

EMS emergency medical service

EPA U.S. Environmental Protection Agency

NOAA National Oceanic and Atmospheric Administration

NWS National Weather Service

PCA Philadelphia Corporation for Aging

SMSA standard metropolitan statistical area

SSC spatial synoptic classification

TWG Technical Working Group

UL Underwriter Laboratories
Excessive Heat Events Guidebook
Summary

Summary

Introduction

Excessive heat events (EHEs) are and will continue to be a fact of life in the United States. 

These events are a public health threat because they often increase the number of daily 

deaths (mortality) and other nonfatal adverse health outcomes (morbidity) in affected 

populations. Distinct groups within the population, generally those who are older, very 

young, or poor, or have physical challenges or mental impairments, are at elevated risk for 

experiencing EHE-attributable health problems. However, because EHEs can be accurately 

forecasted and a number of low cost but effective responses are well understood, future 

health impacts of EHEs could be reduced. This guidebook provides critical information 

that local public health officials and others need to begin assessing their EHE vulnerability 

and developing and implementing EHE notification and response programs. 

Health impacts of EHEs

EHE conditions are defined by summertime weather that is substantially hotter and/or 

more humid than average for a location at that time of year. EHE conditions can increase 

the incidence of mortality and morbidity in affected populations. Recent examples of 

EHE health impacts include:

More than 15,000 deaths in France alone (all of western Europe was affected) 

attributed to EHE conditions in August 2003

More than 700 deaths attributed to EHE conditions in Cook County, Illinois, in July 

1995

Roughly 120 deaths attributed to EHE conditions in Philadelphia, Pennsylvania, in 

July 1993.

Concern over the potential future health impacts of EHEs follows research conclusions 

that EHEs may become more frequent, more severe, or both in the United States. 

Responding to EHE conditions

The potential for reducing future health impacts of EHEs in the United States is 

significant for several reasons. 

First, meteorologists can accurately forecast EHE development and the severity of the 

associated conditions with several days of lead time. This provides an opportunity to 

activate established EHE notification and response plans or to implement short-term 

emergency response actions absent an existing plan. 

Second, specific high-risk groups typically experience a disproportionate number of 

health impacts from EHE conditions. The populations that have physical, social, and 

economic factors and the specific actions that make them at high risk include:

Older persons (age > 65)

Infants (age < 1)

The homeless

The poor

People who are socially isolated 
 Excessive Heat Events Guidebook

People with mobility restrictions or mental impairments

People taking certain medications (e.g., for high blood pressure, depression, 

insomnia) 

People engaged in vigorous outdoor exercise or work or those under the influence of 

drugs or alcohol. 

Identifying these high-risk groups in given locations allows public health officials to 

develop and implement targeted EHE notification and response actions that focus 

surveillance and relief efforts on those at greatest risk.

Third, broad consensus exists on the types of actions that will provide relief to those at 

risk during EHEs and help minimize associated health impacts. These actions include:

Establishing and facilitating access to air-conditioned public shelters 

Ensuring real-time public access to information on the risks of the EHE conditions 

and appropriate responses through broadcast media, web sites, toll-free phone lines, 

and other means 

Establishing systems to alert public health officials about high-risk individuals or 

those in distress during an EHE (e.g., phone hotlines, high-risk lists)

Directly assessing and, if needed, intervening on behalf of those at greatest risk (e.g., 

the homeless, older people, those with known medical conditions). 

Experience in several North American cities has demonstrated that comprehensive and 

effective EHE notification and response programs can be developed and implemented at 

relatively low cost. These programs generally use available resources instead of creating 

EHE-specific institutions. This approach recognizes that short-term resource reallocations 

for EHEs are justified by the severity of their public health risks, the limited duration and 

frequency of the events, and the cost-effectiveness of the reallocations. 

Guidebook goals and next steps 

This guidebook provides interested public health officials with enough background 

information on EHE risks and impacts to roughly assess potential local health risks from 

EHEs. In addition, it provides a menu of notification and response actions to consider 

when developing or enhancing a local EHE program.

The 2005 U.S. hurricane season was a stark reminder that inadequate public and private 

preparation and response to well-forecasted and well-understood extreme meteorological 

phenomena can have severe public health consequences. 

The remaining public health challenge for EHEs is to develop and implement meaningful 

EHE notification and response programs that increase public awareness and lessen future 

adverse health impacts. 
Overview

Chapter 1

Overview

EHEs can increase the number of deaths (mortality) and nonfatal outcomes (morbidity) 

in vulnerable populations, including older people, the very young, the homeless, and 

people with cognitive and physical impairments (NOAA, 1995; American Medical 

Association Council on Scientific Affairs, 1997; Semenza et al., 1999). Climate research 

suggests that future health risks of EHEs could increase with an increase in EHE frequency 

and severity (Meehl and Tebaldi, 2004). At the same time, demographic patterns including 

increasing urbanization will increase the size and percentage of the vulnerable U.S. 

population. To develop appropriate EHE responses, local officials need to understand the 

risks that these events pose to their populations and their response options. The intent of 

this guidebook is to address both needs.

1.1 Why Care about EHEs?

Studies estimate that the combined EHE-attributable summertime mortality for several 

vulnerable U.S. metropolitan areas is well above 1,000 deaths per year (Kalkstein, 1997; 

Davis et al., 2003a). Although similar research to quantify EHE-attributable mortality in 

rural areas has not been completed, recent research (Sheridan and Dolney, 2003) found 

evidence of such an impact. 

Despite the history of adverse health impacts, there is consensus that most of these 

outcomes are preventable (CDC, 2004a). Lessening future adverse health outcomes from 

EHEs will require improving the awareness of public health officials and the general 

public about the health risks of EHEs while continuing to develop and implement 

effective EHE notification and response programs.

1.2 Guidebook Goals

This guidebook has two basic goals: first, to provide local health and public safety officials 

with the information they need to develop EHE criteria and evaluate the potential health 

impacts of EHEs, and second, to offer a menu of EHE notification and response actions to 

be considered.

To meet these goals, this guidebook is organized as follows.

Chapter 2 provides information on EHE-attributable health impacts and sources of risk 

that affect the vulnerability of individuals and communities to EHEs. Specific information 

provided in the chapter includes: 

A general EHE definition 

Guidance on criteria for EHE forecasting and identifying EHE conditions 

Estimates of the number and rate of EHE-attributable summertime deaths for select 

U.S. metropolitan areas 

A review of the meteorological, demographic, behavioral, and regional characteristics 

that increase health risks from EHEs. 

1
 Excessive Heat Events Guidebook

Chapter 1

Chapter 3 gives the menu of notification and response options that local officials can use 

as a starting point when considering whether to develop or enhance an EHE program. 

This menu consists of the following information:

The components of current EHE notification and response programs 

Case studies of specific EHE response programs to understand their development and 

lessons learned 

A review of the efficacy of EHE response programs. 

Chapter 4 provides recommendations that should be considered when developing an 

EHE notification and response program. Specifically, this chapter contains:

Guidance on specific actions to consider when planning to develop or enhance an 

EHE program 

Recommendations for coordinating EHE programs with other public health 

programs (e.g., ozone alert programs).

In addition, the guidebook includes a series of appendices with information that officials 

may want to incorporate in other materials or make available independent of the 

guidebook. This information includes:

A partial list of resources for additional information on EHE-attributable health risks 

and impacts and details on EHE programs (Appendix A)

Guidance on the personal use of portable electric fans during EHEs (Appendix B)

A summary of specific actions people and communities can take in response to 

forecast EHE conditions to reduce the risk of experiencing heat-attributable health 

problems (Appendix C). 

1.3 Guidebook Development 

Other documents have summarized the health risks of EHEs, described the factors that 

increase an individual’s health risk during these conditions, and recommended elements 

for EHE notification and response programs (e.g., Basu and Samet, 2002; Bernard and 

McGeehin, 2004; CDC, 2004a,c; FEMA, 2005b; U.S. EPA, 2005).

This guidebook, however, is unique because it was developed as a collaborative effort 

among several of the principal federal agencies responsible for addressing EHEs: the 

Centers for Disease Control and Prevention (CDC), the National Oceanic and Atmospheric 

Administration’s (NOAA’s) National Weather Service (NWS), the U.S. Department of 

Homeland Security (DHS), and the U.S. Environmental Protection Agency (EPA) along with 

three other institutions with extensive experience developing and operating recognized 

EHE programs in the United States and abroad: the Philadelphia Health Department, 

Toronto Public Health, and the University of Delaware Center for Climatic Research.

Summarizing the collective insight and experience of the individuals from these 

organizations was facilitated through the participation of their staff in a Technical 

Working Group (TWG). The TWG helped shape the guidebook’s content through regular 

group discussions and review of draft versions of the guidebook.
EHE Health Impacts and Risk Sources

Chapter 2

EHE Health Impacts and Risk Sources 

This chapter first defines an EHE and reviews possible criteria for identifying EHE 

conditions, followed by a discussion of the range of EHE-attributable medical conditions, 

adverse health outcomes, and mortality estimates for several U.S. metropolitan areas. It 

also reviews the characteristics that can affect an individual’s health risk and the incidence 

of adverse health outcomes in a population. 

2.1 Defining an EHE

EHE conditions are defined by summertime weather that is substantially hotter and/or 

more humid than average for a location at that time of year. Because how hot it feels 

depends on the interaction of multiple meteorological variables (e.g., temperature, 

humidity, cloud cover), EHE criteria typically shift by location and time of year. In other 

words, Boston, Philadelphia, Miami, Dallas, Chicago, San Diego, and Seattle are likely to 

have different EHE criteria at any point in the summer to reflect different local standards 

for unusually hot summertime weather. In addition, these criteria are likely to change for 

each city over the summer. As a result, reliable fixed absolute criteria, e.g., a summer day 

with a maximum temperature of at least 90°f, are unlikely to be specified. 

There are different ways to identify EHE conditions. Some locations evaluate current and 

forecast weather to identify EHE conditions with site-specific, weather-based mortality 

algorithms. Other locations identify and forecast EHE conditions based on statistical 

comparisons to historical meteorological baselines. For example, the criterion for EHE 

conditions could be an actual or forecast daily high temperature that is equal to or exceeds 

the 95th percentile value from a historical distribution for a defined time period (e.g., the 

summer or a month-long window centered on the date). 

Figure 2.1 presents a hypothetical example that shows the difference in defining 

EHE conditions when using a seasonally adjusted relative temperature versus a fixed 

temperature criterion. 

Figure 2.1. An example illustrating the difference between a seasonally adjusted relative 

temperature threshold and a fixed absolute temperature threshold for defining EHE 

conditions. Source: Personal communication, B. Davis, New Hope Environmental Services, August 2005.

2
10 Excessive Heat Events Guidebook

Chapter 2

Representations of actual EHEs can help illustrate these conditions. During the summer 

of 2003, Western Europe experienced EHE conditions of unprecedented severity. Figure 

2.2 presents the June through August 2003 daily maximum temperature readings in Paris 

with the corresponding average daily maximum temperature from the historical record. 

Although the June and July temperatures in Figure 2.2 may not seem exceptional, 

the extent to which they generally exceeded the long-term average shows why Paris 

experienced EHE conditions. The period from August 3 to August 17, however, is notable 

for its absolute temperatures and its tremendous deviation from typical conditions. 

Reflecting the significant health risks of EHE conditions, France experienced roughly 

15,000 heat-related deaths during this period (Koppe et al., 2004). 

2.2 Health Risks Attributable to EHE Conditions 

Maintaining a consistent internal body temperature, generally 98.6°f, is essential to 

normal physical functioning (American Medical Association Council on Scientific Affairs, 

1997). EHE conditions stress the body’s ability to maintain this ideal internal temperature. 

If individuals fail or are unable to take steps to remain cool and begin to experience 

increasing internal temperatures, they increase their risk of experiencing a range of 

potential adverse health outcomes. 

Table 2.1 lists some of the medical conditions directly attributable to excessive heat 

exposure, along with recommended responses. 

EHE conditions can result in increases in the number of cases of other health problems 

as well. For example, EHEs can increase the number of patients experiencing circulatory 

system conditions. These additional problems come from the added strain on the heart, 

increasing circulation to regulate internal temperatures, or to overcome the effects of 

dehydration, which thickens the blood, making it harder for the heart to pump. 

Figure 2.2. Actual (red line) vs. average (black line) daily maximum temperatures
EHE Health Impacts and Risk Sources 11

Chapter 2

2.3 Quantifying the Health Impacts of EHEs

Quantifying the health impacts of EHEs is complicated by the differences in 

quantification methods and a lack of accurate data.

The most conservative quantification method counts only outcomes on EHE days where 

the attribution information (e.g., primary diagnosis, cause of death) lists excessive 

weather-related heat exposure or a condition unequivocally associated with excessive 

heat exposure, such as heat stroke. This approach underestimates the health impacts of 

EHEs because not all the heat-related cases will include an attribution that recognizes 

this impact. More inclusive methods quantify EHE health impacts based on increases in 

outcomes during EHE periods compared to long-term averages. But such approaches 

can be absolute and attribute all observed increases in outcomes to EHEs, overestimating 

the heat-related mortality. Alternatively, the approach can be partial and attribute only a 

portion of the observed increase in outcomes to EHEs based on professional judgment or 

the results of additional analyses such as regression.

Table 2.1. Medical conditions directly attributable to excessive heat exposure

Medical Condition Symptoms Responses

Heat cramps Painful muscle cramps and 

spasms, usually in muscles 

of legs and abdomen. 

Heavy sweating.

Apply firm pressure on cramping muscles 

or gently massage to relieve spasm. 

Give sips of water; if nausea occurs, 

discontinue water intake. Consult with a 

clinician or physician if individual has fluid 

restrictions (e.g., dialysis patients).

Heat exhaustion Heavy sweating, weakness, 

cool skin, pale, and clammy. 

Weak pulse. Normal 

temperature possible. 

Possible muscle cramps, 

dizziness, fainting, nausea, 

and vomiting.

Move individual out of sun, lay him or her 

down, and loosen clothing. Apply cool, 

wet cloths. Fan or move individual to airconditioned room. Give sips of water; if 

nausea occurs, discontinue water intake. 

If vomiting continues, seek immediate 

medical attention. Consult with a clinician 

or physician if individual has fluid 

restrictions (e.g., dialysis patients).

Heat stroke 

(sunstroke)

Altered mental state. 

Possible throbbing 

headache, confusion, 

nausea, and dizziness. 

High body temperature 

(106°F or higher). Rapid 

and strong pulse. Possible 

unconsciousness. Skin 

may be hot and dry, or 

patient may be sweating. 

Sweating likely especially 

if patient was previously 

involved in vigorous activity.

Heat stroke is a severe medical 

emergency. Summon emergency medical 

assistance or get the individual to a 

hospital immediately. Delay can be fatal. 

Move individual to a cooler, preferably 

air-conditioned, environment. Reduce 

body temperature with a water mister 

and fan or sponging. Use air conditioners. 

Use fans if heat index temperatures are 

below the high 90s. Use extreme caution. 

Remove clothing. If temperature rises 

again, repeat process. Do not give fluids.

Sources: CDC, 2004a; Kunihiro and Foster, 2004; NWS, 2004.
12 Excessive Heat Events Guidebook

Chapter 2

2.3.1 EHEs and U.S. mortality

There are a number of methods for estimating the public health threat and impact of 

EHEs. Since these methods can have a significant impact on the resulting estimate, it 

is important to recognize their differences when reviewing information describing the 

public health burden of EHEs. 

The most conservative estimate of EHE mortality counts only cases in which exposure to 

excessive heat is reported on a death certificate as a primary or contributing factor. Using 

this approach, it was estimated that extreme heat from weather conditions is, on average, 

responsible annually for 182 deaths in the United States (CDC, 2002). 

The conservative nature of this estimate due to the narrow criteria is recognized in the 

study itself (CDC, 2002). The accuracy of this estimate would improve with widespread 

adoption of revised criteria for attributing a death to excessive heat exposure. Typically, 

medical examiners list heat exposure as a primary or contributing cause of death only 

if the core body temperature exceeds 105°f. In the revised criteria, a death also can be 

classified as heat-related if the person is “found in an enclosed environment with a high 

ambient temperature without adequate cooling devices and the individual had been 

known to be alive at the onset of the heat wave” (Donoghue et al., 1997). Importantly, the 

National Association of Medical Examiners supports using these broader criteria, and 

medical examiners in several large cities (e.g., Philadelphia) have adopted them.

Alternative EHE mortality estimates come from analyses of daily urban summertime 

mortality patterns in the United States (Kalkstein and Greene, 1997; Davis et al., 2003a). 

These studies first defined EHE conditions and then calculated the number of EHEattributable deaths based on differences in daily deaths on EHE days compared to longerterm averages. Although differences in the time series, definitions of urban populations, 

and other analytical methods prevent an exact comparison of results from Kalkstein and 

Greene (1997) and Davis et al. (2003a), their findings correspond closely [for details of the 

studies’ methods and the comparison of results see accompanying background technical 

report (Mills, 2005)]. Table 2.2 presents the estimates of heat-attributable excess deaths 

and mortality rates from these studies. 

The results in Table 2.2 are notable for several reasons. First, despite differences in 

methods and the locations evaluated, the studies’ results fall in a narrow range of roughly 

1,700-1,800 total heat-attributable deaths per summer. These estimates are roughly an 

order of magnitude greater than the comprehensive national annual average of 182

deaths with a listed cause of death of “excessive heat due to weather conditions” (CDC, 

2002). This difference highlights the importance of the method (i.e., excess incidence 

or attributed outcomes) used to quantify EHEs’ health impacts. Although summing the 

results across different groups of locations minimizes some of the initial distinctions 

in the studies, some of the location-specific results in Table 2.2 show that significant 

differences can result from applying different methods to essentially the same mortality 

and meteorological data.

Second, both studies’ results show significant regional variation: EHEs have the greatest 

impact in the Northeast and Midwest and the least impact in the South and Southwest. 

This result is consistent with hypotheses that populations in the most vulnerable areas are 

not as acclimatized to elevated temperatures and that structures in less susceptible areas 
EHE Health Impacts and Risk Sources 13

Chapter 2

Table 2.2 Estimates of heat-attributable deaths per summer and mortality rates in 

select U.S. metropolitan areas

Standard 

Metropolitan 

Statistical 

Area (SMSA)

Deaths1

(Estimated average 

summertime heatattributable deaths 

from 1990 population)

Deaths2

(Estimated average 

summertime heatattributable deaths 

from 1990 population)

Mortality Rate1

(Estimated heatattributable deaths 

per 100,000,

1990s baseline)

Mortality Rate2

(Estimated heatattributable deaths 

per 100,000,

1990s baseline)

Birmingham 42 N/A 5.00 N/A

Providence 47 N/A 4.14 N/A

Hartford 38 N/A 3.28 N/A

St. Louis 79 0 3.17 0.00

Kansas City 49 0 3.10 0.00

Buffalo 33 19 2.78 1.63

Indianapolis 36 N/A 2.61 N/A

Memphis 25 N/A 2.48 N/A

Columbus 33 N/A 2.45 N/A

Minneapolis 59 0 2.32 0.00

Chicago 191 193 2.32 2.34

Philadelphia 129 71 2.19 1.21

Denver 42 22 2.12 1.09

Detroit 110 124 2.12 2.39

Greensboro 22 0 2.10 0.00

Nassau, New 

York City, Newark 362 552 1.85 2.82

Louisville 17 N/A 1.79 N/A

Boston 96 56 1.76 1.03

Pittsburgh 39 40 1.63 1.69

New Orleans 20 30 1.56 2.31

Tampa 28 0 1.35 0.00

Baltimore; 

Washington, D.C. 84 40 1.25 0.59

Cleveland 29 23 1.01 0.80

Dallas 36 0 0.89 0.00

Atlanta 25 75 0.84 2.51

Cincinnati 14 0 0.77 0.00

Portland 9 32 0.50 1.76

Los Angeles 

and Riverside 72 216 0.50 1.50

San Francisco 28 138 0.45 2.21

San Antonio 4 N/A 0.30 N/A

Houston 7 0 0.19 0.00

Seattle 5 96 0.17 3.27

Jacksonville 0 N/A 0.00 N/A

Miami, Fort 

Lauderdale 0 0 0.00 0.00

Phoenix 0 6 0.00 0.30

Salt Lake City 0 N/A 0.00 N/A

San Diego 0 N/A 0.00 N/A

Norfolk N/A 0 N/A 0.00

Charlotte N/A 0 N/A 0.00

Total 1,810 1,733

Note: N/A, not applicable, refers to a metropolitan area not examined in one of the studies. 

1. Kalkstein and Greene, 1997.

2. Davis et al., 2003a.
14 Excessive Heat Events Guidebook

Chapter 2

are better designed to accommodate elevated temperatures. However, fewer locations were 

evaluated in the South and Southwest because of the studies’ population selection criteria, 

so support for these hypotheses remains qualified. This regional result is more evident in 

Figure 2.3, which presents the Kalkstein and Greene (1997) results along with a similar 

result for Toronto (N. Day, personal communication, Toronto Public Health, 2005).

EHE-attributable mortality estimates from specific EHEs are also available:

Chicago, 1995, mid-July EHE: The county coroner certified 465 heat-related deaths 

in Chicago (Cook County, Illinois) from July 11 to July 27, 1995 (CDC, 1995). More 

than 700 deaths in Chicago were eventually attributed to this EHE (e.g., Palecki et 

al., 2001). The difference reflects deaths directly attributed to heat by the medical 

examiner (CDC, 1995) and estimates of the total excess mortality attributable to the 

EHE based on studies of daily mortality patterns (Palecki et al., 2001).

Philadelphia, 1993, early-July EHE: The county coroner certified 118 heat-related 

deaths in Philadelphia from July 6 to July 14, 1993 (CDC, 1994).

These estimates demonstrate that an EHE in the United States can easily be responsible 

for hundreds of deaths in a large metropolitan area.

2.3.2 EHEs and U.S. morbidity

EHE morbidity studies are relatively rare because of a lack of suitable daily time-series 

data. Further, when such studies are attempted, only the most severe morbidity outcomes 

(emergency room visits and hospitalizations) tend to be evaluated because of the limited 

number of locations where patients can be seen and be treated. 

One of the few U.S. EHE morbidity studies examined Chicago hospital admissions during 

the July 1995 EHE. Semenza et al. (1999) calculated that this EHE was responsible for 

more than 1,000 hospital admissions, and anecdotal evidence strongly suggests that this 

EHE increased the incidence of Chicago emergency room visits. Specifically, the Natural 

Disaster Survey Report: July 1995 Heat Wave (NOAA, 1995) reported that on the second 

day of the EHE, only a few Chicago emergency rooms were directing ambulances to other 

facilities because of crowding (i.e., operating in bypass status), but by the fourth day, 18

city emergency rooms were doing so. 
EHE Health Impacts and Risk Sources 15

Chapter 2

Figure 2.3. Estimated EHE-attributable mortality rates.

Note: Locations shown with a value of 0 may have deaths that are attributed to excessive heat exposure. This result simply means that there has not been a measurable increase in mortality from any cause during EHEs compared to other summertime periods.Sources: Original mortality estimates from Kalkstein and Greene (1997). Converted to rates with the 1990 Census population estimates for the SMSAs. Toronto results from personal communication with N. Day, Toronto Public Health (2005).
16 Excessive Heat Events Guidebook

Chapter 2

In summary, available evidence suggests that EHEs increase morbidity incidence. 

More complete assessments of EHE impacts, including evaluations of EHE impacts on 

less severe outcomes, may require carefully designed retrospective surveys in affected 

populations. 

2.4 Identifying Characteristics that Affect EHE Health Risks

Several factors can increase health risks during an EHE: the EHE’s meteorological 

conditions, demographic characteristics, personal behavioral choices, and regional 

characteristics.

2.4.1 Meteorological conditions

When the weather gets hotter, the risk of losing control of one’s internal temperature 

increases. Heat index tables such as the one in Table 2.3 are commonly used to capture 

interactions among several meteorological variables to provide a measure of how hot it 

feels. Even heat index table results are sensitive, however, to the particular meteorological 

variables measured. For example, heat index results, including those in Table 2.3, often 

assume measurements are taken in a shaded location with light wind. As a result, most 

heat index tables also note that exposure to direct sunlight can increase heat index values 

by up to 15°f. These table notes may also state that exposure to hot dry winds can further 

increase health risks by promoting rapid dehydration, although a quantitative measure of 

these conditions’ impact is not provided (NWS Forecast Office, Pueblo, Colorado, 2004). 

Ultimately, a change in any meteorological variable that increases heat index values or 

promotes dehydration will increase the individual’s health risk. 

EHE conditions represent a “shock” that can overwhelm typical responses to elevated 

temperatures. All else being equal, the shock value and the health risks increase the earlier 

in the summer the EHE occurs (Kalkstein and Davis, 1989; Sheridan and Kalkstein, 1998)

because residents adapt, to some degree, to warmer summer conditions over the season. 

Similarly, health risks increase with the duration of the EHE measured as the number of 

consecutive EHE days (Greene and Kalkstein, 1996) and the amount of time spent above 

minimum temperature thresholds (Kalkstein and Davis, 1989). 

Table 2.3. Heat index values (°F)3, 4

Temperature 

(°F)

Relative Humidity (%)

90 80 70 60 50 40

80 85 84 82 81 80 79

85 101 96 92 90 86 84

90 121 113 105 99 94 90

95 133 122 113 105 98

100 142 129 118 109

105 148 133 121

110 135

3. Heat index values were not given for the temperature and relative humidity combinations that have blank 

cells.

4. Heat index values can be up to 15oF higher with exposure to direct sunlight. Heat index values assume 

calm wind conditions; hot dry winds can also increase heat index values. 

Source: NWS Forecast Office, Pueblo, Colorado, 2004.
EHE Health Impacts and Risk Sources 17

Chapter 2

2.4.2 Demographic sensitivities 

Individuals possessing any combination of the following characteristics or conditions are 

at greater risk for experiencing an EHE-attributable adverse health outcome:

Physical constraints: It is difficult for some people to increase their circulation 

and perspiration during an EHE to help them remain cool. This at-risk group 

includes infants, older people (age 65 and older, who may also be less likely to 

recognize symptoms of excessive heat exposure), the obese, the bedridden, those with 

underlying medical conditions (e.g., heart disease, diabetes), those taking certain 

medications (e.g., for high blood pressure, depression, insomnia), and individuals 

under the influence of drugs or alcohol. 

Mobility constraints: People with mobility constraints are at higher risk during EHEs 

if the constraints limit their ability to access appropriately cooled locations. This 

group includes the very young and the bedridden. 

Cognitive impairments: People with mental illnesses, with cognitive disorders, or 

under the influence of drugs or alcohol may be unable to make rational decisions 

that would help limit their exposure to excessive heat or to recognize symptoms of 

excessive heat exposure. 

Economic constraints: The poor may be disproportionately at risk during 

EHEs if their homes lack air conditioning or they are less likely to use available 

air conditioning because of the cost (NWS, 2004). In addition, if the poor 

disproportionately reside in high crime areas, fear of crime can increase their risks 

by hindering their willingness to take appropriate responses [e.g., opening doors 

and windows for circulation, visiting cooling shelters (American Medical Association 

Council on Scientific Affairs, 1997)].

Social isolation: Socially isolated individuals are less likely to recognize symptoms 

of excessive heat exposure. This can delay or prevent treatment and result in more 

serious health outcomes. Members of this group, which include the homeless and 

those living alone, may also be less willing or able to reach out to others for help. 

2.4.3 Behavioral choices

In addition to demographic characteristics, the choices individuals make during an EHE 

can have a profound effect on the health risks they face. Examples of personal choices that 

can increase an individual’s health risks during an EHE include the following (American 

Medical Association Council on Scientific Affairs, 1997; CDC 2004a,c; NWS, 2004):

Wearing inappropriate clothing: Heavy, dark clothing can keep the body hot and 

limit cooling from evaporation of perspiration. Clothing that exposes skin to the sun 

increases the risk of sunburn, which limits the potential for evaporative cooling.

Failing to stay adequately hydrated: During EHE conditions, we rely heavily on 

perspiration to regulate our body temperature. Without enough water consumption, 

perspiration will be inadequate or even cease and body temperature will rise. 
18 Excessive Heat Events Guidebook

Chapter 2

Consuming alcohol: Alcohol is a diuretic and thus limits perspiration. It can also 

impair judgment and result in excessive exposure to the elevated temperatures. 

Engaging in outdoor activities: Any activities that increase exposure to the sun or 

generate additional body heat (e.g., attending outdoor events, exercising, outdoor 

labor) increase the amount of body heat that must be dissipated.

Eating inappropriate meals: Eating hot and heavy (e.g., high-protein) foods will 

increase the metabolic rate and increase the amount of body heat that must be 

dissipated.

2.4.4 Regional factors

Finally, regional characteristics can help determine an individual’s health risks during 

EHEs. These characteristics include:

Geographic location: Climate variability is largely a function of location, and 

increased variability has been associated with elevated heat-attributable mortality 

rates (Chestnut et al., 1998). 

Urbanization and urban design: As buildings, especially those with dark roofs, and 

dark paving materials replace vegetation in urban areas, the heat absorbed during 

the day increases and cooling from shade and evaporation of water from soil and 

leaves is lost. Urban areas can also have reduced air flow because of tall buildings, 

and increased amounts of waste heat generated from vehicles, factories, and air 

conditioners. These factors can contribute to the development of an urban heat 

island, which has higher daytime maximum temperatures and less nighttime cooling 

than surrounding rural areas (see Figure 2.4). Urban heat islands can increase health 

risks during EHEs by increasing the potential maximum temperature residents are 

exposed to and the length of time that they are exposed to elevated temperatures. 

Residential location: Residents on the upper floors of buildings will feel the effects 

of rising heat. This can elevate room temperatures and make it more difficult to 

maintain a consistent internal temperature if air conditioning is not available or is not 

used, or if ventilation is restricted.

Figure 2.4. Impact 

of the urban heat 

island on ambient 

temperatures.

Source: U.S. EPA, 

2006.
EHE Health Impacts and Risk Sources 19

Chapter 2

Table 2.4 summarizes the factors that increase the risk of an individual getting sick or 

dying from an EHE.

Table 2.4. Factors that increase an individual’s risk of experiencing an EHE-attributable 

adverse health outcome

Meteorological Characteristics

Increased temperature

Increased relative humidity

Dry, hot winds

Demographic Characteristics

Physical constraints (including underlying medical conditions)

Mobility constraints

Cognitive impairments

Economic constraints

Social isolation

Behavioral Choices

Wearing inappropriate clothing

Failing to stay adequately hydrated

Consuming alcohol

Engaging in outdoor activities

Eating heavy and/or hot foods 

Regional Characteristics

Living in an area with a variable climate

Living in an urban area

Living on the upper floors of buildings
20 Excessive Heat Events Guidebook

Chapter 2
Summary of Current 

EHE Notification & Response Programs

Summary of Current EHE Notification and Response Programs 21

Chapter 3

Effective EHE notification and response programs draw on available local resources and 

recognize local constraints to minimize increases in morbidity and mortality during 

EHEs. As a result, effective EHE notification and response programs can vary. 

This chapter summarizes the current range of observed response actions to EHE 

conditions. Not all of these actions will be feasible or appropriate for every location. 

This summary is intended to provide parties wanting to develop or enhance an EHE 

notification and response program with a “menu” of possible actions to consider.

This summary has a number of caveats. First, the reviewed EHE programs were selected to 

provide an illustrative rather than all-inclusive set of notification and response actions. As 

a result, specific actions that are important components of other effective EHE programs 

may have been omitted. Second, our exclusion of specific actions in this summary is not 

a judgment on their potential benefit. In fact, developing and evaluating notification and 

response actions in response to local conditions is strongly encouraged. 

This chapter first summarizes actions incorporated in the EHE programs we reviewed. 

This is followed by narratives that offer insight into how and why the reviewed programs 

were developed, and summarize critical lessons their administrators have learned over 

time. The chapter also describes several short-term responses that the city of Phoenix, 

Arizona, implemented during the EHE in the southwestern and central United States 

in July 2005. These Phoenix responses are included to highlight actions that can be 

taken with relatively short notice to address exceptional EHEs even if a formal EHE 

program has not been developed. Finally, the chapter reviews evidence from studies 

that have attempted to quantify the impact of EHE notification and response programs. 

Although limited, such studies provide some perspective on the potential benefits of EHE 

notification and response programs.

3.1 Elements in Select EHE Programs

On the following page, Table 3.1 summarizes the actions Philadelphia and Toronto 

incorporated in their EHE notification and response programs. These programs were 

selected because they are widely recognized as benchmarks for those considering 

developing a comprehensive EHE program. 

Following Table 3.1, the individual elements are described in greater detail.

3
22 Excessive Heat Events Guidebook

Chapter 3

Table 3.1. Summary of confirmed EHE program elements in Philadelphia and Toronto

Program elements Philadelphia5 Toronto6

Prediction see 3.1.1, p. 23 

Ensure access to weather forecasts capable of predicting 

EHE conditions 1-5 days in advance 4 4

Risk assessment see 3.1.2, p. 23 

Coordinate transfer and evaluation of weather forecasts by 

EHE program personnel 4 4

Develop quantitative estimates of the EHE’s potential 

health impact 4 4

Use the broader criteria to identify heat-attributable deaths 4 4

Develop information on high-risk individuals 4

Develop an accessible record on facilities and locations 

with concentrations of high-risk individuals 4 4

Notification and response see 3.1.3, p. 24 

Coordinate public broadcasts of information about the 

anticipated timing, severity, and duration of EHE conditions 

and availability and hours of any public cooling centers 

4 4

Coordinate public distribution and broadcast of heat 

exposure symptoms and tips on how to stay cool during 

an EHE 

4 4

Operate informational phone lines that can be used to 

report heat-related health concerns 4 4

Designate public buildings or specific private buildings 

with air conditioning as public cooling shelters and 

provide transportation

4 4

Extend hours of operation at community centers with air 

conditioning 4

Arrange for extra staffing of emergency support services 4

Directly contact and evaluate the environmental conditions 

and health status of known high-risk individuals and 

locations likely to have concentrations of these individuals

4 4

Increase outreach efforts to the homeless and establish 

provisions for their protective removal to cooling shelters 4 4

Suspend utility shutoffs 4 4

Reschedule public events to avoid large outdoor 

gatherings when possible 4

Mitigation see 3.1.4, p. 26 

Develop and promote actions to reduce effects of urban 

heat islands Not evaluated

5. NOAA, 1995; Kalkstein, 2002.

6. Kalkstein, 2002; personal communications, M. Vittiglio and N. Day, Toronto Public Health, 2005.
Summary of Current EHE Notification and Response Programs 23

Chapter 3

3.1.1 EHE prediction 

Ensure access to weather forecasts capable of predicting EHE conditions 

1-5 days in advance 

Forecasting the development and characteristics of an EHE is a critical element of 

both EHE risk assessment and notification and response activities. In the United 

States, NWS forecasts provide national coverage, so any location could incorporate 

this element into an EHE program. Toronto and Philadelphia both use a sophisticated, 

air mass-based heat health system developed by the Center for Climatic Research at 

the University of Delaware to evaluate meteorological forecast data in terms of the 

potential to increase the number of daily deaths above average levels (Sheridan and 

Kalkstein, 2004).

3.1.2 EHE risk assessment

Coordinate transfer and evaluation of weather forecasts by EHE program 

personnel

In some locations, EHE program personnel may need to review forecast data to 

determine whether location-specific criteria for EHE conditions are satisfied and, 

potentially, how the forecast conditions match with any established EHE severity 

criteria. Establishing forecast transfer and evaluation protocols involves specifying 

under what conditions forecasters (e.g., the NWS) forward information to local 

officials (and confirm receipt) and identifying who within the EHE program reviews 

and evaluates the information. Alternatively, electronic systems can be established 

to retrieve and review forecast data from meteorologists and notify EHE program 

personnel if certain criteria are satisfied. 

Develop quantitative estimates of the EHE’s potential health impacts

Several locations with EHE notification and response programs, including 

Philadelphia and Toronto, have integrated heat health watch/warning systems that use 

meteorological forecast data as inputs to health impact models, which identify when 

forecast conditions could result in excess mortality and then estimate the potential 

number or probability of heat-attributable deaths (Sheridan and Kalkstein, 2004). 

These quantitative health impact estimates are then used in both cities to determine if 

and what type of heat emergency is declared. These determinations affect the type and 

scope of notification and response activities that will be implemented. 

Use the broader criteria to identify heat-attributable deaths

Medical examiners can use the criteria in Donoghue et al. (1997) to define heatattributable deaths and to provide the public with more accurate reporting of an EHE’s 

health impacts. This information can increase public awareness and appreciation of 

the health risks of the conditions, which may improve compliance with recommended 

actions. 

Develop information on high-risk individuals

Recognizing that some individuals have an elevated risk facilitates notifying and 

responding to these individuals (e.g., older individuals, the homeless) to achieve 

the greatest public health benefit for a given resource commitment. Easily accessible 

contact information for these individuals during an EHE can help the program 
24 Excessive Heat Events Guidebook

Chapter 3

prioritize assessment and intervention efforts. In some locations such as Chicago, 

the development of information on high-risk individuals has been expanded beyond 

persons known to public agencies. It includes people and organizations who can 

identify high-risk individuals so they can be a part of any active assessment and 

intervention program efforts. 

Develop an accessible record of facilities and locations with concentrations 

of high-risk individuals

A database or list of high-risk facilities and locations would complement a list of highrisk individuals. This list could help prioritize active assessment efforts during an EHE 

(e.g., visiting retirement homes) to coordinate EHE notification activities through 

combinations of fax, email, or telephone contact trees. For example, in Toronto, more 

than 800 community agencies are notified of EHE conditions through a fax/call-out 

tree. 

3.1.3 EHE notification and response 

Coordinate public broadcasts of information about the anticipated timing, severity, and 

duration of EHE conditions, and availability and hours of any public cooling centers

Effective public notification of forecast EHE conditions helps eliminate the risk of an 

EHE taking a population by surprise. More specifically, notifying the public of anticipated 

EHE conditions will enable many residents to prepare and will enable public assessment 

and intervention actions to concentrate on known high-risk individuals and locations. 

Likewise, advance public notification about the availability of cooling centers will increase 

the likelihood that at-risk individuals can take advantage of these services. 

Coordinate public distribution and broadcast of heat exposure symptoms 

and tips on how to stay cool during EHEs

Publicly broadcasting cooling tips and symptoms of excessive heat exposure will 

complement similar broadcasts about forecast EHE conditions and help residents 

develop appropriate EHE responses (e.g., seek air-conditioned locations, minimize 

direct sun exposure, reschedule outdoor gatherings). When possible, this action would 

include providing this information before and throughout the summer to public 

meeting areas (e.g., churches, recreation centers, libraries, schools), arranging periodic 

broadcasts through available media, and developing EHE Internet sites. 

Operate informational phone lines that can be used to report heat-related 

health concerns

Telephone help lines give real-time advice and information that can help people stay 

safe and avoid serious outcomes. This phone system either can be activated when 

an EHE is forecast (e.g., Philadelphia’s or Toronto’s Heat Lines), or can be a more 

general, full-time system (e.g., a 311 line) staffed during EHEs by personnel with 

the information and ability to access and direct other intervention resources (e.g., 

emergency medical staff) as needed.
Summary of Current EHE Notification and Response Programs 25

Chapter 3

Designate public buildings or specific private buildings with air conditioning 

(e.g., shopping malls, movie theaters) as public cooling shelters and provide 

transportation if necessary 

Spending time in an air-conditioned environment during an EHE is one of the most 

effective means of reducing one’s risk of overheating. By designating specific public 

buildings with air conditioning as cooling shelters, and by providing information on 

large private buildings with air conditioning where the public can freely congregate 

(e.g., shopping malls and movie theaters), local officials can increase the awareness 

and use of these resources to minimize an EHE’s health impacts. Providing free public 

transportation to those locations during an EHE also recognizes that many with the 

greatest need for the shelters may have limited access to personal transportation and 

limited financial resources.

Extend hours of operation at community centers with air conditioning

Many of those at greatest risk during an EHE may already frequently visit specific airconditioned public locations (e.g., child care and senior centers). Extending the hours 

of operation at these and other public locations with air conditioning during EHEs 

increases the opportunity for high-risk individuals to spend time in an air-conditioned 

environment. 

Arrange for extra staffing of emergency support services

EHEs will place additional burdens on emergency medical and social support services 

through increased activity focused on preventing adverse health outcomes and 

increased need for medical services. Increasing the staffing of emergency medical and 

social support services in response to an EHE forecast increases the opportunity to 

avert some outcomes with intervention and assessment activities or at least have them 

addressed at an earlier and less severe stage by preventing the emergency medical 

system from becoming overwhelmed.

Directly contact and evaluate the environmental conditions and health status 

of known high-risk individuals and locations likely to have concentrations of 

these individuals

High-risk individuals need to be contacted directly and, preferably, observed several times 

a day during EHEs 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 early as possible. This labor-intensive action is offset by 

a reduction in the number and severity of adverse health outcomes among the highrisk population. The individuals to be contacted and locations to be visited would be 

identified in the risk assessment component of the EHE program (see Section 3.1.2).

Increase outreach efforts to the homeless and establish provisions for their 

protective removal to cooling shelters

The homeless are vulnerable during EHEs, so additional effort must be devoted to 

homeless outreach and evaluation during an EHE, especially during the day. This 

increased outreach effort should be supported by authorization for officials to move 

individuals believed to be experiencing medical difficulties or at extreme risk to cooling 

shelters for observation and treatment. 
26 Excessive Heat Events Guidebook

Chapter 3

Suspend utility shutoffs 

Suspending utility service during an EHE could significantly increase the risk of 

exposure to elevated temperatures. As a result, many local governments require local 

utilities to suspend shutoffs during EHEs if they do not already have their own shutoff 

suspension guidelines. However, suspending utility shutoffs during an EHE does not 

ensure that at-risk individuals with access to air conditioning will use it.

Reschedule public events to avoid large outdoor gatherings, when possible

When an EHE is forecast, there are likely to be previously scheduled outdoor activities 

involving large gatherings of individuals (e.g., youth league games, outdoor camps, 

concerts). If these activities take place as scheduled, many people may experience 

significant heat exposure. To the extent that local officials have control over how these 

events proceed (e.g., through permits or use of facilities), efforts should be made to 

reschedule the event or, when rescheduling is not feasible, require more medical staff 

and “cool zones” for attendees. 

3.1.4 EHE mitigation

Develop and promote actions to reduce effects of urban heat islands

Urban heat islands can increase daytime temperatures and limit nighttime cooling. 

This can increase the severity and duration of urban residents’ exposure to high-heat 

conditions and increase their risk for experiencing a heat-attributable adverse health 

outcome. Programs and actions that increase urban vegetation and the reflectiveness of 

urban surfaces help address this problem. 

3.2 Case Studies in the Development and Implementation 

of EHE Programs

This section uses case studies from Philadelphia, Toronto, and Phoenix to show how 

different forces can drive the development and implementation of EHE notification and 

response programs and summarizes the lessons learned over time in these locations. These 

insights are especially useful because these programs cover a broad geographic spectrum 

and reflect varying degrees of active program coordination. 

3.2.1 Philadelphia

Overview

Philadelphia’s EHE notification and response program is often viewed as a benchmark for 

integrated, urban EHE programs. Philadelphia has a long history of EHE impacts, with 

references to heat-attributable deaths recorded since colonial times. The development 

of this program demonstrates how an exceptional meteorological event can combine 

with seemingly minor bureaucratic adjustments to create significant public interest and 

support for an EHE notification and response program. 

This EHE program’s development also demonstrates the importance of institutional 

support and shows how response actions can be matched to program partners based on 

their areas of expertise. Finally, the program highlights the benefits of incorporating a 

system for active program review and adjustment to respond to needs, constraints, and 

opportunities as they arise. 
Summary of Current EHE Notification and Response Programs 27

Chapter 3

Development of Philadelphia’s EHE program

Philadelphia’s EHE notification and response program is a direct response to observable 

public health impacts from specific EHEs combined with the public recognition of these 

risks and institutional support to develop an effective response to avoid similar outcomes 

in the future. 

In the summer of 1991, more than 20 deaths in Philadelphia were attributed to excessive 

heat exposure. In response, the city established and began to convene meetings of a Heat 

Task Force under the direction of Health Department staff. The Health Department 

identified original task force participants by informally assessing public and private 

organizations that served at-risk individuals during an EHE or provided Philadelphia with 

critical infrastructure and medical services (e.g., electric and water utilities and emergency 

medical service providers). 

The Heat Task Force continued to meet through the spring of 1993, but had made little 

progress in developing what would be recognized as an EHE notification and response 

program. Then, from July 4 to July 14, 1993, Philadelphia experienced EHE conditions 

characterized by minimum daily high temperatures of at least 90°f. By July 6, the risks 

were apparent and publicly recognized as the city health commissioner announced that 

people were dying because of EHE conditions. 

At the same time, informal discussions between Health Department staff and 

Southeastern Pennsylvania Red Cross board members led to the establishment of the 

Heatline, a telephone hotline, to handle calls from residents with heat-related questions 

and concerns. The Heatline, which represented the extent of the city’s direct response 

actions to the EHE, operated for five days, and its number was widely reported by local 

media. 

Perhaps the most critical aspect of the July EHE, in terms of its contribution to the 

development of the current EHE program, was that the city medical examiner broke from 

requiring a core body temperature in excess of 105°f for listing a death as heat related. 

Instead, deaths were listed as heat related if the core temperature criterion was satisfied 

or if a body was “found in an enclosed environment with a high ambient temperature 

without adequate cooling devices and the individual had been known to be alive at the 

onset of the heat wave” (Donoghue et al., 1997). 

This change resulted in the medical examiner classifying 105 deaths during the July 1993

EHE as heat related. In contrast, for all of July, New York City and Washington, D.C., 

which had experienced similar meteorological conditions, reported three and two heatrelated deaths, respectively, using solely the core temperature criterion. 

This finding and its public reporting made the impact of excessive heat in Philadelphia 

a topic of considerable local and national media interest, including references to 

Philadelphia as the “Heat Death capital of the world.” In addition, the contrast between 

the number of heat-related deaths reported in Philadelphia and the totals from 

surrounding counties and other urban centers led to a request by state and other officials 

for a CDC investigation into the appropriateness of the coding criterion the Philadelphia 

medical examiner used. The resulting investigation ultimately concluded that the criterion 

was appropriate and the associated estimates of heat-attributable mortality were accurate. 
28 Excessive Heat Events Guidebook

Chapter 3

Following the CDC investigation, and with increased public attention on the health risks 

of EHE conditions, staff at Philadelphia’s Health Department became aware of work 

under the direction of Dr. Laurence Kalkstein of the University of Delaware to develop 

a system that would identify weather conditions expected to increase daily mortality. 

Ultimately, this interest led to the development by the summer of 1995 of a computerized 

system capable of forecasting EHE conditions up to two days in advance. 

Over this period, spurred by the events of 1993, the Philadelphia Heat Task Force began 

preparing EHE response plans that identified lead agencies, secured formal commitments 

of support from relevant departments, and worked on developing a system for integrated 

communications between program participants. 

As the July 1995 EHE developed in the Midwest and the scope of its health impact began 

to emerge (eventually more than 700 deaths in Chicago would be classified as heat 

related), the Philadelphia Hot Weather-Health Watch/Warning System was announced at a 

meeting with EPA and Philadelphia Health Department officials. This system was initially 

implemented as the EHE moved eastward into Philadelphia. 

Philadelphia’s Hot Weather-Health Watch/Warning System response actions

Philadelphia’s initial EHE program implemented combinations of the following actions 

depending on the predicted severity of the EHE (NOAA, 1995; Kalkstein et al., 1996):

Media announcements: Local news media were notified of any EHE notification 

made by the health commissioner. Media were also given background information on 

how to minimize exposure to heat during the event and encouraged to broadcast it as 

part of any heat-related stories. 

Buddy system advocacy: Media messages included recommendations for friends, 

relatives, neighbors, and block captains (see discussion below) to check on local highrisk residents (e.g., sick and older individuals) throughout the day during the event. 

Heatline activation: The same phone system staffed by the Red Cross that was 

developed for the 1993 EHE was part of the formal program rollout. 

Home visits by Health Department staff (currently a county sanitarian and nurse 

make up each field team): Individuals were identified from calls received on the 

Heatline. 

Halt to service shutoffs: Agreements were reached with the respective utilities that 

electrical and water service would not be shut off for nonpayment during periods for 

which the Health Department issued a high heat warning. 

Increased emergency medical service staffing: Increased numbers of staff with 

the city’s Fire Department and Emergency Medical Services were on duty for the 

duration of the high heat period. 

Increased outreach to the homeless: Activities that involved identifying homeless 

individuals and providing shelter were extended to daytime hours to minimize their 

exposure to the most severe conditions. 
Summary of Current EHE Notification and Response Programs 29

Chapter 3

Cooling shelters/senior refuge: Hours of operation at air-conditioned senior 

centers were extended to provide a refuge for those otherwise lacking access to air 

conditioning. 

Outreach: The Heatline phone number was displayed on the Crown Lights display in 

downtown Philadelphia (an electronic billboard on top of the Philadelphia Electric 

Company building that is visible over a large area).

Two notable aspects of the Philadelphia Watch/Warning System that warrant additional 

discussion are its use of block captains and its use of field assessment teams from the 

Health Department to evaluate high-risk individuals during EHEs. 

Philadelphia’s block captains are a critical point of interaction between the public and 

the Health Department during EHEs. Block captains are volunteers elected by residents 

of their block to help coordinate neighborhood improvement projects with the city. 

Philadelphia currently has about 5,000 block captains. They can both identify and evaluate 

the health status of high-risk and hard-to-reach individuals in their residential area during 

an EHE. Although block captains are not required to contact specific individuals during a 

declared EHE, anecdotal evidence suggests that many do. Their actions most likely benefit 

others and, during declared heat events, news crews frequently record and broadcast 

block captains checking on the status of high-risk individuals in their area, spreading the 

message to check on those at risk. 

The second notable aspect of Philadelphia’s program is its coordinated use of field teams 

composed of city Health Department staff in follow-up visits to at-risk individuals 

identified from Heatline calls. Teams assembled during a declared heat event currently 

consist of a sanitarian and a nurse who have been temporarily reassigned from their 

typical duties. This reallocation of staff reflects a belief that a more immediate and more 

significant public health risk is being addressed. 

Adjustments and lessons learned

Since 1995, a number of relatively minor changes have been made in the response elements 

of Philadelphia’s EHE program, including the following:

Transferring the Heatline’s operation from the Red Cross to the Philadelphia 

Corporation for Aging (PCA) and using the PCA’s Senior Line number to double 

as the Heatline. When EHEs are announced, the hours of operation for the Senior 

Line/Heatline are expanded from between 8 a.m. and 5 p.m. to between 8 a.m. and 

midnight.

Adding nurses to the on-call Heatline staff to handle calls with specific medical 

questions.

Mailing heat information to block captains to distribute in their areas.

Increasing the forecast period for the spatial synoptic classification (SSC)-based Heat 

Health Watch Warning System from 2.5 days (60 hours) to 5.0 days (120 hours). 
30 Excessive Heat Events Guidebook

Chapter 3

Philadelphia’s experience demonstrates the importance of public recognition of EHE 

health risks and of continued support from upper levels of government for developing 

an EHE notification and response program. The city’s program also shows that matching 

responsibilities of program elements with program partners who already perform similar 

tasks is critical for achieving a wide range of response actions. Specific examples of this 

matching in the Philadelphia program include shifting the Heatline from the Red Cross to 

the PCA, staffing field teams with temporarily reassigned Health Department personnel, 

and incorporating the city’s existing block captain program to create a community-based 

buddy system capable of evaluating the status of high-risk individuals. 

3.2.2 Toronto

Overview

Toronto is one of several North American locations with an EHE notification and 

response program that is driven by calculations of potential excess mortality or mortality 

probability based on forecast meteorological conditions. Toronto Public Health’s EHE 

program uses these results to determine when heat warnings should be issued and what 

type of message to communicate. 

Toronto’s EHE program is of special interest because it evolved primarily as a proactive, 

precautionary response to a perceived public health risk by local politicians. This is in 

contrast to most of the other highly active and integrated programs, which typically 

originated as responses to EHEs that triggered recognizable increases in daily mortality 

and morbidity. In addition, Toronto’s program is an example of how an effective 

program can be developed by drawing general lessons from other locations and tailoring 

implementation to respond to local opportunities and challenges. Finally, the routine, 

structured process of performance review, needs assessment, and adjustment of the 

Toronto EHE program is noteworthy. 

Development of the Toronto EHE program

The origins of Toronto’s EHE program can be traced to 1998 and the Mayor’s Task Force 

on Homelessness. This effort established a lead role for Toronto Public Health to identify 

and develop responses to the health issues faced by the city’s homeless. In the spring of 

1999, the Task Group asked Toronto Public Health to establish temperature thresholds that 

would be used to initiate health alerts and trigger additional homeless interventions (e.g., 

increasing daytime staff and efforts to get the homeless indoors). 

To address this task, Toronto Public Health staff reviewed information from several 

EHE programs in the United States, including those in Philadelphia and Chicago. 

This review increased awareness of the demographic and physical characteristics that 

increase EHE vulnerability and highlighted the potential for an effective EHE program. 

Most importantly, this review increased awareness among officials that, although the 

homeless were especially vulnerable to EHE conditions, the presence of other high-risk 

subpopulations meant that EHEs should be recognized as a much larger threat to public 

health. 
Summary of Current EHE Notification and Response Programs 31

Chapter 3

Development of an EHE prediction system similar to the one used in Philadelphia and 

several other U.S. cities began in 2000. The Toronto prediction system was completed and 

became active on June 18, 2001, in time to assist in forecasting the EHE that occurred in 

August of that year. Initial program elements focused on issuing a media release any time 

EHE conditions were forecast that contained information about the health risks of the 

conditions and appropriate responses. These announcements were also used to trigger 

increased intervention activities directed at the homeless population. 

With the program’s development, Toronto Public Health also established a Hot Weather 

Response Committee to develop, monitor, and update its Hot Weather Response Plan. The 

committee is a partnership of representatives from various city departments and agencies 

working with potentially vulnerable populations. Every year, before the hot season, the 

committee discusses and finalizes the contributions and roles each agency will assume 

during the coming summer. Using a call-out tree, Toronto Public Health coordinates the 

plan and notifies the committee and a list of more than 800 agencies of an EHE. Each 

agency and city department implements its part of the plan. 

Adjustments and lessons learned

In the fall of each year, the Hot Weather Response Committee meets to assess the 

performance of the system and program. The focus of this meeting is on identifying areas 

and items that could be added or improved to enhance the program’s performance. This 

active review process has resulted in these changes to the program:

Having the Red Cross operate an informational heat-health telephone line during 

declared heat advisories

Coordinating the city’s emergency medical service (EMS) with the health line to 

address specific medical questions, conduct follow-up visits with all callers to evaluate 

conditions in their residences, and to take individuals to cooling centers when needed

Providing functional drinking water fountains in city parks

Extending the hours of operation of city pools

Providing transit tokens to those who have been evaluated by street patrol teams and 

are found to be in need of a cooling center. 

Less formal program adjustments over time have included coordinating with other 

city officials to evaluate and, when necessary, relax enforcement of certain ordinances 

to allow compliance with cooling tips provided during EHEs. For example, the city 

relaxes enforcement of late-night park closure rules, because many residents who lack air 

conditioning visit Toronto’s parks at night during EHE conditions. 

Finally, a critical component of the Toronto EHE program has involved working to 

increase public education and awareness of EHEs and their health risks. To this end, 

Toronto Public Health holds an annual media event in mid-May at which Health 

Department, Red Cross, and EMS staff members are available to answer EHE questions 

from the media. 
32 Excessive Heat Events Guidebook

Chapter 3

3.2.3 Phoenix

Summer in Phoenix is, by any measure, hot. Daily high temperatures above 100°f are 

routine, temperatures up to 110°f are common, and temperatures above 120°f are possible. 

Although residents over time physically adapt to some extent to Phoenix’s high heat, 

summer conditions can still be quite variable. Despite Phoenix routinely experiencing 

life-threatening summertime temperatures, studies of excess heat mortality there have 

consistently found little evidence of any major heat-attributable excess mortality impacts 

(e.g., Kalkstein and Greene, 1997; Davis et al., 2003a,b).

7

Although definitive explanations for this result cannot yet be offered, it seems likely 

that this can be attributed to significant local experience in responding to elevated 

temperatures, relatively low humidity, extensive access to air conditioning, widespread 

public recognition of the health risks during EHE conditions, and a willingness to 

make appropriate adjustments to minimize heat exposure. These findings suggest the 

importance of having a public that understands the health risks inherent in EHEs and 

knows how to minimize their health impacts.

Still, in mid-July 2005, much of the southwestern and central United States experienced 

consecutive days of hot weather that broke all-time high temperature records in many 

locations. During this period, Phoenix was a focus of media attention because of the 

duration of the conditions (all but 3 days in the 2-week period through July 21 reached 

110°f) and because several deaths were attributed to the heat (Associated Press, 2005). 

Extreme high temperatures like those experienced in July 2005, however, create potentially 

life-threatening conditions for anyone experiencing unmitigated exposure, regardless 

of adaptation. As a result, it is not surprising that the majority of deaths in Phoenix 

attributed to the heat were of homeless individuals. Phoenix’s sudden increase in heatattributable deaths in July 2005 should be viewed as a reflection of how an exceptionally 

severe and long-lasting EHE can overwhelm even highly adapted populations.

Before the 2005 summer, Phoenix’s EHE program consisted mainly of relying on the local 

NWS forecast office to predict dangerous conditions and the local media to broadcast 

warnings and advice for limiting heat exposure. Although Phoenix is covered by an 

operating SSC-based EHE prediction system, developed with funding by NOAA’s NWS 

and the local electrical utility to help guide utility shutoff decisions, there was minimal 

interest in incorporating this available information into a broader EHE notification and 

response program.

Adjustments and lessons learned

Phoenix’s public response to the July 2005 EHE conditions largely focused on opening 

homeless shelters during daytime hours, bringing homeless individuals to these and other 

locations with air conditioning, and providing donated bottled water. Given the general 

prevalence of air conditioning in Phoenix, this targeted action may be the most effective 

approach for limiting the health risks and impacts of an especially severe EHE. 

7 A lack of evidence of a heat-mortality relationship in these studies does not mean that excessive heat is 

not reported as a contributing factor in deaths in Phoenix during the summer; in fact, heat-related deaths 

are routinely reported. This finding simply means there has not previously been a measurable increase in 

all-cause mortality rates in Phoenix when the heat reaches exceptional levels. 
Summary of Current EHE Notification and Response Programs 33

Chapter 3

This action also demonstrates how a location that generally lacks a formal EHE program 

can take immediate steps to reduce the risks and health impacts of an especially severe 

EHE.

In addition, the July 2005 EHE in Phoenix triggered a review of the county’s response 

plans to EHE warnings issued by the local NWS office. Although this review is ongoing, 

the revised plan is expected to clearly define a set of actions the county will take after an 

NWS announcement. 

3.3 Evidence on the Performance of EHE Programs

Few studies have evaluated the efficacy of EHE notification and response programs. 

This reflects the difficulty of developing these studies (e.g., issues in identifying case and 

control locations and accounting for variation in populations and EHE conditions) and, 

in many cases, the brevity of existing operating EHE programs. 

One study in Philadelphia (Ebi et al., 2004) used regression analysis to quantify the impact 

of publicly announcing forecast EHE conditions on EHE-attributable excess mortality 

from 1995 to 1998. This study was possible largely because, at the time, the city and the 

regional NWS forecast office independently evaluated forecast data for anticipated EHE 

conditions. As a result, during this period there were days when the city’s criteria called 

for an EHE warning but the NWS would not issue one, days when the city’s system would 

suggest a warning be issued and the NWS would issue one, and days when the NWS 

would issue a warning when the city’s system did not call for a warning. 

Ebi et al. (2004) found that for each day Philadelphia issued an EHE warning based on the 

SSC system recommendation, expected mortality was reduced by roughly 2.6 lives per day 

and this mortality reduction was experienced for the 3 days following the last issued heat 

warning. This result was statistically significant at the 8% level, which the authors note is 

equivalent to saying there was a 92% chance that the system saved at least one life during 

this period. It is estimated that the system saved 117 lives during the study period. To place 

this result in a cost-benefit framework, the authors report an estimated cost, primarily 

for wages of extra emergency medical staff, of $10,000 for each day a heat advisory is 

issued. In contrast, EPA routinely assumed a value per avoided statistical life year lost of $6

million in regulatory impact assessments at the time of the study. 

The other formal study that examined the effectiveness of EHE programs, Palecki et al. 

(2001), compared the health impacts of EHEs in 1995 and 1999 in Chicago and St. Louis. 

The basis for evaluating the effectiveness of EHE programs in this study is provided 

mainly by the contrast of the impacts of the events in Chicago, which lacked an EHE 

notification and response program in 1995 but then developed one, which became active 

in 1999. The authors take care to note that there were differences in the duration, intensity, 

and meteorological conditions preceding the two EHEs, but they focus primarily on the 

fact that 700 deaths were attributed to the 1995 EHE in Chicago compared to roughly 100

deaths from the 1999 event. The authors then argue that much of this sharp reduction in 

mortality can be attributed to the effectiveness of Chicago’s EHE program, which, among 

other actions, included reminding the public of the toll the 1995 EHE had taken to convey 

the risks of the 1999 conditions. 
34 Excessive Heat Events Guidebook

Chapter 3

Additional anecdotal evidence from Philadelphia supports the contention that the city’s 

EHE program has had a beneficial public health impact. Specifically, although more than 

100 deaths in Philadelphia were attributed to the July 1993 EHE, the 1995 EHE experienced 

in the city resulted in only 60-70 heat-attributable deaths after the city’s EHE program 

was implemented that summer [personal communication, Jerry Libby, Philadelphia Health 

Promotion Department (retired), September 27, 2005]. This reduced mortality is even more 

notable given the higher temperatures and longer duration of the 1995 event. 

These results provide limited quantitative evidence that EHE notification and response 

programs can demonstrably improve public health.
Recommendations for EHE Notification and Response Programs 35

Chapter 4

Summary Recommendations for 

EHE Notification & Response Programs

A central theme of this guidebook is the importance of accounting for local conditions 

and populations when defining EHE conditions and developing and implementing EHE 

notification and response programs. Despite the recognized difficulty of addressing 

all combinations of program needs, opportunities, and constraints that users of this 

guidebook may encounter, general recommendations that draw on available data, research 

results, and experience with EHE programs can be made. 

The foundation for these recommendations is the recognition that EHEs are but one of 

a much larger group of extreme meteorological events (e.g., blizzards, floods, hurricanes, 

tornadoes) and anthropogenic conditions (i.e., urban smog) that can adversely affect 

public health. These recommendations are organized according to data needs and actions 

that we believe an EHE notification and response program must address to provide public 

health benefits. Specifically, the recommendations are organized into the following general 

areas: EHE definition and forecasting, public education and awareness of EHE risk factors 

and health impacts, EHE response preparation, EHE response actions, and EHE program 

review and evolution. 

Each area has two categories of recommendations. Strongly recommended actions address 

information or actions we believe an EHE notification and response program must 

address to help minimize heat-attributable public health impacts. The second category 

of recommendations offers guidance on additional actions or data development that 

could enhance the public health effectiveness of an EHE program once the program has 

addressed the strongly recommended actions.

4.1 EHE Definition and Forecasting

As with notification and response programs for other extreme meteorological events, the 

effectiveness of an EHE notification and response program will initially be constrained 

by its ability to define and accurately forecast the relevant meteorological conditions. The 

recommendations in this section are intended to ensure timely access to locally relevant 

EHE forecast information. 

4.1.1 EHE criteria must reflect local conditions

Many established meteorological criteria are used to determine whether forecast or 

existing conditions can be labeled as a certain type of extreme meteorological event 

(e.g., using maximum sustained wind speeds to identify and categorize hurricane 

conditions). A distinguishing feature for most of these criteria is that they do not vary by 

location. 

In contrast, this guidebook’s Technical Working Group (TWG) strongly recommends 

that EHE criteria be defined based on a review of local meteorological data. For example, 

a criterion that defines anticipated EHE conditions on all days with a forecast maximum 

temperature of 100°f or greater would not be useful in locations where this temperature 

has never been observed or in areas where such temperatures are common. In contrast, 

a criterion that announces anticipated EHE conditions any time the forecast daily 

maximum temperature is greater than the 95th percentile value for that day from the past 

30 years would allow for variation by location. 

4
36 Excessive Heat Events Guidebook

Chapter 4

Incorporating evidence of heat-attributable adverse health impacts from analyses 

of health outcomes and weather conditions can enhance EHE criteria development. 

Thus analyses of historical meteorological conditions should incorporate available 

health outcome data (e.g., regression-based analyses of daily mortality as a function of 

meteorological variables or air masses). Adding additional control variables that have 

been identified as affecting the number of heat-attributable health outcomes (e.g., time 

of season, prior EHEs in the season) would enhance the results of these analyses. Further, 

the results of any enhanced weather-health outcome analyses could be used in a predictive 

fashion to calculate the potential health impact of forecast conditions. These predictive 

models could then provide a basis for defining EHE conditions based on predicted 

changes in health outcomes.

4.1.2 Ensure access to timely meteorological forecasts 

An effective EHE notification and response program requires access to reliable 

meteorological forecasts to provide lead time for implementing program elements. 

To forecast EHEs, we strongly recommend that local officials in the United States use and 

evaluate the meteorological data in the NWS’ 5-day regional forecasts. 

To enhance EHE forecasting, we recommend developing systems that electronically 

retrieve and evaluate revised NWS forecast data as they become available. For example, 

the University of Delaware’s Center for Climatic Research has developed automated 

computer systems for existing EHE notification and response programs that retrieve NWS 

forecasts as they are updated, assess the forecast data against EHE criteria over the 5-day 

forecast period, and notify EHE program managers when EHE criteria are satisfied. 

The TWG also recommends that cities not use surveillance-based systems as the primary 

means for identifying EHE conditions. Specifically, systems that rely on observable 

increases in the demand for medical services such as ambulance calls or demand for 

emergency room services to identify EHE conditions are not recommended. Although 

such systems may have a role in determining appropriate resource allocation during an 

EHE, they are of little value as a forecast tool because they do not provide the necessary 

lead time for implementing EHE responses.

4.2 Public Education and Awareness of EHE Risk Factors and 

Health Impacts 

A significant source of the public health impacts of EHEs is that individuals either 

fail to adequately recognize the danger associated with EHE conditions or make poor 

response choices during EHEs. This is tragically reflected by conclusions that most EHEattributable deaths are preventable (CDC, 2004a,c). This conclusion also suggests that 

there is a significant need for continued and enhanced public education about the EHEattributable risks and health impacts.

4.2.1 Increase and improve EHE notification and public education 

The TWG strongly recommends there be a formal system for notifying the public 

when EHE conditions are forecast. At a minimum, announcements made using this 

system should include information on the anticipated arrival, duration, and severity of 

the forecast EHE. In addition, these announcements need to provide the public with 

information about critical EHE risk factors (e.g., being very young or old, using certain 
Recommendations for EHE Notification and Response Programs 37

Chapter 4

medications, having physical or mental impairments that restrict mobility, or lacking the 

ability to respond to environmental changes), the symptoms of excessive heat exposure, 

and recommended response actions (e.g., seek air-conditioned locations, stay hydrated). 

These announcements can be conveyed to the public through usual methods such as 

television, radio, and newspapers, and by using established health alert networks such 

as those operated by some state health departments (e.g., Minnesota). EHE information 

could also be periodically distributed through other avenues such as fliers in newspapers, 

local magazines, and church and civic group literature at the start of and periodically 

throughout the EHE season. Announcements should describe basic precautionary steps 

individuals can take to limit the health risks: stay hydrated; spend time in air-conditioned 

environments; wear loose-fitting, light-colored clothing; check on individuals with highrisk characteristics [see Rudnick (2002) and U.S. EPA Aging Initiative (2004) for more 

detailed information]. The announcements should also suggest appropriate responses 

when symptoms of excessive heat exposure are observed. 

One way to enhance the public education program for EHE risks, impacts, and personal 

response strategies is to repeatedly present a clear and consistent message to varied 

audiences. An example of such an effort is Toronto Public Health’s hosting of an EHE 

media day each May before the start of the summer heat season. During this event, 

Toronto Public Health provides the media with information about the city’s EHE 

notification and response program and answers questions about the health risks and 

impacts of EHEs. This event maintains media interest in the program and generally results 

in reporting that keeps EHEs in the public’s eye. 

An example of another broad-based educational activity that could be pursued is EHE 

education programs for schools. These programs would help inform a vulnerable 

segment of the population about risks and appropriate responses and could potentially 

provide an effective means of having central messages repeated and adopted by a range of 

households. 

EHE education should also be specifically directed at first responders and local emergency 

management personnel as well as to those who care for older individuals, the very young, 

the homeless, and the physically and mentally challenged. This targeted education would 

inform critical response personnel and caregivers about the health risks EHEs pose to 

members of the vulnerable groups they look after and emphasize the need for active 

assessment and intervention to prevent adverse health outcomes. 

4.2.2 Provide information on proper use of portable electric fans during EHEs

The TWG also strongly recommends that, as part of a public education program, cities 

emphasize that portable electric fans are not the simple cooling solution they appear to 

be. Because of the limits of conduction and convection, using a portable electric fan alone 

when heat index temperatures exceed 99°f actually increases the heat stress the body must 

respond to by blowing air that is warmer than the ideal body temperature over the skin 

surface (American Medical Association Council on Scientific Affairs, 1997; CDC, 2004c). In 

these conditions, portable electric fans provide a cooling effect by evaporating sweat. The 

increased circulation of hot air and increased sweat evaporation can, however, speed the 

onset of heat-attributable conditions (e.g., heat exhaustion). 
38 Excessive Heat Events Guidebook

Chapter 4

Thus, portable electric fans need to be used with caution and under specific circumstances 

during an EHE, such as exhausting hot air from a room or drawing in cooler air through 

an open window. Generally, portable electric fans may not be a practical and safe cooling 

mechanism during an EHE in homes that are already hot and are not air-conditioned; 

their use should be discouraged unless the fans are bringing in significantly cooler air 

from outside the dwelling. If a resident must stay in these dwellings, and if they are unable 

to access an air-conditioned environment, safer cooling approaches would include taking 

frequent cool showers and drinking cool, nonalcoholic fluids (e.g., ice water). Because of 

the importance of this issue, and the contradictory messages people may have received 

about using portable electric fans during EHEs, Appendix B provides a series of guidelines 

for fan use during EHEs. 

Finally, public officials should review the various educational messages about EHEs 

for consistency with other messages and information on other issues. For example, 

recommendations against letting cars idle to control ozone concentrations would be 

inconsistent with EHE recommendations to stay in air-conditioned environments 

whenever possible. Public officials can recognize any potentially conflicting messages and 

then make clear statements about which message should take precedence during an EHE. 

4.3 EHE Response Preparation

Preparations for an EHE can be distinguished according to when they are initiated relative 

to the development of the EHE. Long-term preparations address actions that need to be 

initiated well before an EHE is forecast because of the time needed to reach necessary 

agreements, develop systems, or secure supplies and personnel. Short-term preparations 

are actions that need to be taken when a multiday forecast anticipates EHE conditions. 

This section focuses on long-term preparations; Section 4.4 covers short-term preparation 

actions. 

4.3.1 Develop a clear plan of action identifying roles and responsibilities

Defining the structure, relationships, and responsibilities for those supporting an EHE 

notification and response program (e.g., health departments, utilities, homeless advocates) 

is an essential long-term action. More generally, this action requires establishing a means 

for planning and communication among the program supporters so that available 

resources are used most efficiently and potentially conflicting messages from program 

participants are clarified. 

To achieve this coordination, the TWG strongly recommends establishing periodic 

meetings among program participants, distributing materials electronically, and 

designating points of contact for each participating group or agency. Variations across 

locations in the structure and expertise of agencies and the presence of different 

private organizations make it problematic to offer specific recommendations about 

recommended organizational structures for an EHE program. However, because EHEs are 

a threat to public health, relevant public health agencies can and should play a significant, 

but not necessarily the lead, role in developing and managing an EHE program. In 

addition, local emergency management agencies, street and sanitation departments, 

and health code enforcement staff typically have significant contact with the public. As 

a result, their information distribution networks and staffs could, depending on local 

conditions, be a valuable resource to consider in EHE response planning. 
Recommendations for EHE Notification and Response Programs 39

Chapter 4

Finally, nonprofits such as the Red Cross, homeless outreach programs, area agencies on 

aging, and senior centers should be actively recruited to become EHE program partners to 

incorporate their expertise in identifying, communicating with, and providing services to 

populations that are at high risk during EHEs. 

When developing a plan of action, we also strongly recommend EHE program partners 

pay particular attention to the potential for public recommendations that could 

conflict during an EHE and provide clear guidance regarding priorities. For example, 

environmental organizations may generally recommend against idling cars for extended 

periods of time to improve air quality. This message could be modified to note that 

if idling is necessary to stay in an air-conditioned environment during an EHE, it is 

acceptable and preferable to exposing the occupants to the heat. 

4.3.2 Develop long-term urban planning programs to minimize 

heat island formation 

Although not the focus of this guidebook, the TWG strongly recommends urban design 

and development programs be reviewed with a goal of promoting actions that will 

help control the development of urban heat islands. The longer timeframes envisioned 

for implementing any actions result in these actions being viewed as part of the EHE 

preparation actions. However, effective implementation of specific actions designed to 

mitigate urban heat islands, such as programs to increase the reflectiveness of urban 

surfaces, increase urban vegetation, and modify behavior, is likely to require a significant 

public education component. 

4.4 EHE Response Actions

This section covers activities that should be initiated after meteorological forecasts 

identify an impending EHE or EHE conditions have been announced. Four essential 

recommendations involve these short-term EHE response actions: 

The public should be encouraged to spend time in available air-conditioned buildings 

(e.g., shopping centers, movie theaters, senior centers, libraries). To the extent 

these types of buildings have air conditioning, they are also generally capable of 

accommodating sudden increases in public use for short periods of time (e.g., a few 

days) without significant difficulty. 

EHE program partners should reallocate resources to address critical short-term 

needs of the EHE that are likely to provide a significant public health benefit. For 

example, this could involve shifting some public health inspectors from inspecting 

dining facilities to visiting nursing homes or supporting home environment 

assessments for individuals who may call available non-911 help lines. Other examples 

could include having homeless agencies emphasize providing daytime services and 

interventions during the EHE instead of nighttime services when conditions will 

generally be cooler. 

Once a forecast for EHE conditions has been aired, the locality should prohibit the 

suspension of electric and water services. For this reason, all meetings related to the 

EHE program should include representatives from local utility companies who have 

been solicited as program partners.
40 Excessive Heat Events Guidebook

Chapter 4

Local medical examiners should be directed to use the guidelines set forth by 

Donoghue et al. (1997) for classifying heat-related deaths. Although statistical 

analyses of total daily mortality can and should be used to identify and quantify 

increases in mortality attributable to the EHE, using the Donoghue et al. guidelines 

will improve the accuracy of estimates of heat-attributable deaths for those who base 

these estimates solely on the information from death certificates. 

Additional recommendations for response actions that could provide additional public 

health benefits include: 

Conducting direct assessments of high-risk individuals during EHEs to check for 

signs of excessive heat exposure 

Increasing the extent and duration of public access to air-conditioned settings 

Increasing the capacity of the emergency medical system to respond to increased 

surveillance and treatment demands. 

Each of these additional recommendations for enhancing short-term responses is 

discussed below. 

EHE health risks are not equally distributed among the population. Therefore, the TWG 

recommends that enhanced program responses include direct assessments of the health 

and environments of those at greatest risk during the EHE. Increasing home visits, using 

telephone check-in systems, and operating toll-free lines to provide advice or receive 

reports of concerns can alert EHE program staff to individuals who may be at the greatest 

risk or experiencing health problems during the EHE and help avoid more serious health 

outcomes. 

Spending time in an air-conditioned environment has long been recognized and 

advocated as the most effective means of preventing heat-attributable health impacts 

during an EHE. To increase the potential time spent in air-conditioned locations, we also 

recommend the hours of operation and number of air-conditioned locations (e.g., senior 

centers, libraries) made publicly available be increased during an EHE. Providing free 

transportation to these locations could also increase their use.

Finally, regardless of the extent of preparations and response implemented for an EHE, 

it is likely that the onset of EHE conditions will result in an increase in the demand for 

emergency medical services in the form of 911 calls, visits to emergency room facilities, 

and increased volume and need for medical examiner staff and services. The TWG 

therefore recommends additional staffing of emergency medical personnel to increase the 

number of people who can receive treatment at any given time, reduce waiting times for 

treatment, or both. Existing local and state mutual aid agreements and state emergency 

medical assistance compacts as well as the resources of state and local emergency 

management agencies, the Federal Emergency Management Agency, the Medical Reserve 

Corps, and the National Disaster Medical System may be available to help meet some of 

these needs. The applicability and availability of these resources need to be evaluated, 

however, and contacts must be established before the onset of EHE conditions. 
Recommendations for EHE Notification and Response Programs 41

Chapter 4

Appendix C provides one-page summaries of the critical actions individuals and EHE 

program partners can and should take once EHE conditions are forecast or are being 

experienced.

4.5 Review EHE Programs to Address Changing Needs, 

Opportunities, and Constraints

Over time, the constraints and opportunities faced by an EHE notification and response 

program will shift and experience will be gained in developing working relationships 

between program partners and in responding to different types of meteorological 

conditions. Finally, the relative importance of EHEs as a public health threat could change 

over time. 

As a result, the TWG strongly recommends establishing a regular and formal review of the 

program’s performance. For example, in the fall, when the risk of an EHE has diminished, 

program partners should evaluate past performance and make recommendations to 

improve the notification and response program. Alternatively, hypothetical “table-top” 

exercises could be conducted that allow program partners to work through how they 

would respond to alternative EHE scenarios in order to identify problems with current 

preparation and response activities and develop solutions. 
42 Excessive Heat Events Guidebook

Chapter 4
References 43

References

References

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American Medical Association Council on Scientific Affairs. 1997. Heat-Related Illness 

During Extreme Weather Emergencies. Report 10 of the Council on Scientific Affairs (A97). Presented at the 1997 AMA Annual Meeting.

American Red Cross. 2005. Heat Waves. http://www.redcross.org/services/

disaster/0,1082,0_586_,00.html.

Associated Press. 2005. Weather: Homeless Hit Hard by Heat. http://www.cnn.com/2005/

WEATHER/07/22/heat.deaths.ap/index.html. Accessed July 22, 2005.

Basu, R. and J.M. Samet. 2002. Relation between elevated ambient temperature and 

mortality: A review of the epidemiologic evidence. Epidemiologic Reviews 24(2):190-202.

Bernard, S.M. and M.A. McGeehin. 2004. Municipal heat wave response plans. American 

Journal of Public Health 94(9):1520-1522.

CDC. 1994. Heat-related deaths – Philadelphia and United States, 1993-1994. Centers for 

Disease Control. Morbidity and Mortality Weekly Report 43(25):453-455.

CDC. 1995. Heat-related mortality – Chicago, July 1995. Centers for Disease Control. 

Morbidity and Mortality Weekly Report 44(31):577-579. 

CDC. 1996. Heat-wave-related mortality – Milwaukee, Wisconsin, July 1995. Morbidity 

and Mortality Weekly Report 45(24):505-507. 

CDC. 1997. Heat-related-deaths – Dallas, Wichita, and Cooke counties, Texas, and United 

States, 1996. Morbidity and Mortality Weekly Report 46(23):528-530.

CDC. 1998. Heat-related mortality – United States, 1997. Morbidity and Mortality Weekly 

Report 47(23):473-476.

CDC. 1999. Heat-related-deaths – Missouri, 1998, and United States, 1979-1996. Morbidity 

and Mortality Weekly Report 48(22):469-472.

CDC. 2000. Heat-related illnesses, deaths, and risk factors – Cincinnati and Dayton, Ohio, 

1999, and United States, 1979-1997. Morbidity and Mortality Weekly Report 49(21):470-473. 

CDC. 2001. Heat-related-deaths – Los Angeles County, California, 1999-2000, and United 

States, 1979-1998. Morbidity and Mortality Weekly Report 50(29):623-626.

CDC. 2002. Heat-related deaths – four states, July-August 2001, and United States, 1979-

1999. Morbidity and Mortality Weekly Report 51(26):567-570.

CDC. 2004a. Extreme Heat: A Prevention Guide to Promote Your Personal Health and 

Safety. http://www.bt.cdc.gov/disasters/extremeheat/heat_guide.asp. Accessed January 24, 

2005.
44 Excessive Heat Events Guidebook

References

CDC. 2004b. Extreme Heat Bibliography. http://www.bt.cdc.gov/disasters/extremeheat/

bibliography.asp. 

CDC. 2004c. Extreme Heat: Tips for Preventing Heat-Related Illness. http://www.bt.cdc.

gov/disasters/extremeheat/heattips.asp. Accessed January 24, 2005.

Chestnut, L.G., W.S. Breffle, J.B. Smith, and L.S. Kalkstein. 1998. Analysis of differences in 

hot-weather-related mortality across 44 U.S. metropolitan areas. Environmental Science 

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Davis, R.E., P.C. Knappenberger, P.J. Michaels, and W.M. Novicoff. 2003a. Changing heatrelated mortality in the United States. Environmental Health Perspectives 111(14):1712-1718.

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in summer mortality in U.S. cities. International Journal of Biometeorology 47(3):166-175.

Donoghue, E.R., M.A. Graham, J. Jentzen, B.D. Lifschultz, J.L. Luke, and H.G. 

Mirchandani. 1997. Criteria for the diagnosis of heat-related deaths: National Association 

of Medical Examiners: Position paper. American Journal of Forensic Medicine and 

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Ebi, K.L., T.J. Teisberg, L.S. Kalkstein, L. Robinson, and R.F. Weiher. 2004. Heat watch/

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FEMA. 2005a. Extreme Heat: Are You Ready? http://www.fema.gov/areyouready/heat.

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FEMA. 2005b. Hazards Backgrounder: Extreme Heat. http://www.fema.gov/hazards/

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Greene, J.S. and L.S. Kalkstein. 1996. Quantitative analysis of summer air masses in the 

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Kalkstein, L.S. 1997. Climate and human mortality: Relationship and mitigating measures. 

Advances in Bioclimatology 5:161-177.

Kalkstein, L. 2002. Description of our Heat/Health Watch-Warning Systems: Their Nature 

Extent, and Required Resources. Prepared for Stratus Consulting, Boulder, CO.

Kalkstein, L.S. and R.E. Davis. 1989. Weather and human mortality: An evaluation of 

demographic and interregional responses in the United States. Annals of the Association 

of American Geographers 79(1):44-64.

Kalkstein, L.S. and J.S. Greene. 1997. An evaluation of climate/mortality relationships 

in large U.S. cities and the possible impacts of a climate change. Environmental Health 

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Kalkstein, L.S., P.F. Jamason, J.S. Greene, J. Libby, and L. Robinson. 1996. The Philadelphia 

Hot Weather-Health Watch/Warning System: Development and application: Summer 

1995. Bulletin of the American Meteorological Society 77(7):1519-1528.
References 45

References

Koppe, C., S. Kovats, G. Jendritzky, and B. Menne. 2004. Heat-Waves: Risks and Responses. 

World Health Organization, Rome.

Kunihiro, A. and J. Foster. 2004. Heat Exhaustion and Heatstroke. http://www.emedicine.

com/emerg/topic236.htm. Accessed November 28, 2005.

LBNL. 2000. Heat Island Group. http://eetd.lbl.gov/HeatIsland/. 

Meehl, G.A. and C. Tebaldi. 2004. More intense, more frequent, and longer lasting heat 

waves in the 21st century. Science 305:994-997.

Mills, D.M. 2005. Excessive Heat Events: A Review of Evidence on Health Risks, Impacts, 

and Opportunities for Response. Prepared for U.S. Environmental Protection Agency, 

Office of Air and Radiation, Office of Atmospheric Programs, Climate Change Division. 

October, 27. 

Milwaukee Health Department and Milwaukee Heat Task Force. 2005. Milwaukee Health 

Department and Milwaukee Heat Task Force: Plan for Excessive Heat Conditions 2005. 

http://www.city.milwaukee.gov/display/displayFile.asp?docid = 2689&filename = /

Groups/healthAuthors/DCP/PDFs/Heat_Plan_2005_-_rev_6-17-05.pdf

NCAR. 2005. Heat Wave Awareness Homepage. http://www.isse.ucar.edu/heat/. 

New York City Office of Emergency Management. 2005. Ready New York: Extreme Heat. 

http://www.nyc.gov/html/oem/html/readynewyork/hazard_heat.html. 

NOAA. 1995. Natural Disaster Survey Report: July 1995 Heat Wave. National Oceanic and 

Atmospheric Administration, Silver Spring, MD.

NWS. 2004. Heat Wave: A Major Summer Killer. National Weather Service. http://www.

nws.noaa.gov/om/brochures/heatwave.pdf. Accessed January 13, 2005.

NWS. 2005. Natural Hazard Statistics. http://www.nws.noaa.gov/om/hazstats.shtml. 

NWS Forecast Office, Pueblo, Colorado. 2004. Heat Index. National Weather Service. 

http://www.crh.noaa.gov/pub/heat.htm. Accessed January 13, 2005.

Palecki, M.A., S.A. Changnon, and K.E. Kunkel. 2001. The nature and impacts of the 

July 1999 heat wave in the midwestern United States: Learning from the lessons of 1995. 

Bulletin of the American Meteorological Society 82(7):1353-1368.

Philadelphia Office of Mental Health & Mental Retardation. 2002. Fan Facts. Philadelphia, 

PA.

Rudnick, A. 2002. Reducing the Risk of Heat Stress Disorders for Consumers of Behavioral 

Health Services: Questions and Answers. Philadelphia Office of Mental Health & Mental 

Retardation, Philadelphia.

Semenza, J.C., J.E. McCullough, W.D. Flanders, M.A. McGeehin, and J.R. Lumpkin. 1999. 

Excess hospital admissions during the July 1995 heat wave in Chicago. American Journal of 

Preventive Medicine 16(4):269-277.
46 Excessive Heat Events Guidebook

References

Sheridan, S.C. and T.J. Dolney. 2003. Heat, mortality, and level of urbanization: Measuring 

vulnerability across Ohio, USA. Climate Research 24:255-266.

Sheridan, S.C. and L.S. Kalkstein. 1998. Heat watch-warning systems in urban areas. World 

Resource Review 10(3):375-383.

Sheridan, S.C. and L.S. Kalkstein. 2004. Progress in heat watch-warning system 

technology. Bulletin of the American Meteorological Society 85:1931-1941.

Toronto Public Health. 2002. Summer Safety: Fan Facts. Toronto, Ontario, Canada.

U.S. EPA. 2005. Heat Wave Response Programs. U.S. Environmental Protection Agency. 

http://epa.gov/heatisland/about/heatresponseprograms.html. Accessed February 22, 2005.

U.S. EPA. 2006. Heat Island Effect. U.S. Environmental Protection Agency. http://www.

epa.gov/heatisland/about/index.html. Accessed January 5, 2006.

U.S. EPA Aging Initiative. 2004. It’s Too Darn Hot: Planning for Excessive Heat Events. 

September. U.S. Environmental Protection Agency. http://www.epa.gov/aging/resources/

epareports.htm#itstoodarnhot. Available in English, low literacy, Spanish, Chinese, 

Vietnamese, Haitian Creole, Russian. Accessed August 3, 2005.
Appendix A: Excessive Heat Event Resources Available on the Internet 47

Appenidix A

Extreme Heat Bibliography

Extreme Heat Bibliography. http://www.bt.cdc.gov/disasters/extremeheat/bibliography.

asp. (CDC, 2004b)

Heat Index Summaries

Heat Index. http://www.crh.noaa.gov/pub/heat.htm. (NWS Forecast Office, Pueblo, 

Colorado, 2004)

Summaries of the Health Risks and Tips for Minimizing Risk 

from Exposure to Elevated Temperatures

Extreme Heat: A Prevention Guide to Promote Your Personal Health and Safety. http://

www.bt.cdc.gov/disasters/extremeheat/heat_guide.asp. (CDC, 2004a)

Extreme Heat: Are You Ready? http://www.fema.gov/areyouready/heat.shtm. (FEMA, 

2005a)

Extreme Heat: Tips for Preventing Heat-Related Illness. http://www.bt.cdc.gov/disasters/

extremeheat/heattips.asp. (CDC, 2004c)

Hazards Backgrounder: Extreme Heat. http://www.fema.gov/hazards/extremeheat/heat.

shtm. (FEMA, 2005b)

Heat-Related Illness During Extreme Weather Emergencies. http://www.ama-assn.org/

ama/pub/category/13637.html. (AMA, 2005)

Heat Wave: A Major Summer Killer. http://www.nws.noaa.gov/om/brochures/heatwave.

pdf. (NWS, 2004)

Heat Wave Awareness Homepage. http://www.isse.ucar.edu/heat/. (NCAR, 2005)

Heat Wave Response Programs. http://epa.gov/heatisland/about/heatresponseprograms.

html. (U.S. EPA, 2005)

Heat Waves. http://www.redcross.org/services/disaster/0,1082,0_586_,00.html. (American 

Red Cross, 2005)

Natural Hazard Statistics. http://www.nws.noaa.gov/om/hazstats.shtml. (NWS, 2005)

Extreme Heat: Tips for Preventing Heat-Related Illness. http://www.bt.cdc.gov/disasters/

extremeheat/heattips.asp. (CDC, 2004c)

Summaries of Existing EHE Programs

Milwaukee Health Department and Milwaukee Heat Task Force: Plan for Excessive 

Heat Conditions 2005. http://www.city.milwaukee.gov/display/displayFile.asp?docid = 

2689&filename = /Groups/healthAuthors/DCP/PDFs/Heat_Plan_2005_-_rev_6-17-

05.pdf. (Milwaukee Health Department and Milwaukee Heat Task Force, 2005)

Ready New York: Extreme Heat. http://www.nyc.gov/html/oem/html/readynewyork/

hazard_heat.html. (New York City Office of Emergency Management, 2005)

Appendix A: Excessive Heat Event 

Resources Available on the Internet
48 Excessive Heat Events Guidebook

Heat Island Effect: Heat Wave Response Programs. http://epa.gov/heatisland/about/

heatresponseprograms.html. (U.S. EPA, 2005)

Urban Heat Island Overview and Control Measures

Heat Island Effect. http://www.epa.gov/heatisland/. (U.S. EPA, 2006)

Heat Island Group. http://eetd.lbl.gov/HeatIsland/. (LBNL, 2000)

EHE Case Studies

Natural Disaster Survey Report: July 1995 Heat Wave. ftp://ftp.nws.noaa.gov/om/

assessments/heat95.pdf. (NOAA, 1995)

Morbidity and Mortality Weekly Report. http://www.cdc.gov/mmwr/

(CDC). Examples:

Heat-Wave-Related Mortality – Milwaukee, Wisconsin, July 1995. June 21, 1996. Vol. 45. 

No. 24. (CDC, 1996)

Heat-Related-Deaths – Dallas, Wichita, and Cooke Counties, Texas, and United States, 

1996. June 13, 1997. Vol. 46. No. 23. (CDC, 1997)

Heat-Related Mortality – United States, 1997. June 19, 1998. Vol. 47. No. 23. (CDC, 1998)

Heat-Related Illnesses, Deaths, and Risk Factors – Cincinnati and Dayton, Ohio, 1999, and 

United States, 1979-1997. Vol. 49. No. 21. (CDC, 2000)

Heat-Related-Deaths – Four States, July-August 2001, and United States, 1979-1999. July 5, 

2002. Vol. 51. No. 26. (CDC, 2002)

Heat-Related-Deaths – Los Angeles County, California, 1999-2000, and United States, 

1979-1998. July 27, 2001. Vol. 50. No. 29. (CDC, 2001)

Heat-Related-Deaths – Missouri, 1998, and United States, 1979-1996. June 11, 1999. Vol. 48. 

No. 22. (CDC, 1999)

Appenidix A
Appendix B: Use of Portable Electric Fans during Excessive Heat Events 49

Appenidix B

Appendix B: Use of Portable Electric 

Fans During Excessive Heat Events

The widespread availability and ease of using portable electric fans draw 

many people to use them for personal cooling during an EHE. Portable 

electric fans can, however, increase the circulation of hot air, which 

increases thermal stress and health risks during EHE conditions. 

As a result, portable electric fans need to be used with caution and under 

specific circumstances during an EHE. Here is a list of Do’s and Don’t’s 

for their use: 

Do

Use a portable electric fan in or next to an open window so heat can 

exhaust to the outside (box fans are best).

Use a portable electric fan to bring in cooler air from the outside.

Plug your portable electric fan directly into a wall outlet. If you need 

an extension cord, check that it is UL (Underwriter Laboratories) 

approved in the United States or CSA (Canadian Standards 

Approved) approved in Canada. 

Don’t

Use a portable electric fan in a closed room without windows or 

doors open to the outside.

Believe that portable electric fans cool air. They don’t. They just move 

the air around and keep you cool by helping to evaporate your sweat. 

Use a portable electric fan to blow extremely hot air on yourself. This 

can accelerate the risk of heat exhaustion.

Use a fan as a substitute for spending time in an air-conditioned 

facility during an EHE.

If you are afraid to open your window to use a portable 

electric fan, choose other ways to keep cool (e.g., cool 

showers, spend time in an air-conditioned location).

Sources: Philadelphia Office of Mental Health & Mental Retardation, 2002; Toronto Public Health, 2002.
50 Excessive Heat Events Guidebook
Appendix C: Excessive Heat Events Guidebook in Brief 51

Appenidix C

Appendix C: Excessive Heat Events 

Guidebook in Brief

Quick Tips for Responding to 

Excessive Heat Events

For the Public

Do

Use air conditioners or spend time in air-conditioned locations 

such as malls and libraries

Use portable electric fans to exhaust hot air from rooms or 

draw in cooler air

Take a cool bath or shower

Minimize direct exposure to the sun 

Stay hydrated – regularly drink water or other nonalcoholic fluids

Eat light, cool, easy-to-digest foods such as fruit or salads

Wear loose fitting, light-colored clothes 

Check on older, sick, or frail people who may need help 

responding to the heat

Know the symptoms of excessive heat exposure and the 

appropriate responses.

Don’t

Direct the flow of portable electric fans toward yourself when 

room temperature is hotter than 90°f

Leave children and pets alone in cars for any amount of time

Drink alcohol to try to stay cool

Eat heavy, hot, or hard-to-digest foods 

Wear heavy, dark clothing.
52 Excessive Heat Events Guidebook

Appenidix C

Useful Community Interventions

For Public Officials

Send a clear public message 

Communicate that EHEs are dangerous and conditions can be 

life-threatening. In the event of conflicting environmental safety 

recommendations, emphasize that health protection should be the 

first priority.

Inform the public of anticipated EHE conditions

When will EHE conditions be dangerous?

How long will EHE conditions last? 

How hot will it FEEL at specific times during the day 

(e.g., 8 a.m., 12 p.m., 4 p.m., 8 p.m.)?

Assist those at greatest risk

Assess locations with vulnerable populations, such as nursing homes 

and public housing

Staff additional emergency medical personnel to address the 

anticipated increase in demand

Shift/expand homeless intervention services to cover daytime hours

Open cooling centers to offer relief for people without air 

conditioning and urge the public to use them.

Provide access to additional sources of information

Provide toll-free numbers and Web site addresses for heat 

exposure symptoms and responses

Open hotlines to report concerns about individuals who may 

be at risk

Coordinate broadcasts of EHE response information in newspapers 

and on television and radio.

Penalty for Private Use: $300

Official BusinessWashington, DC 204601200 Pennsylvania Avenue NWOffice of Atmospheric Programs (6207J)United States Environmental Protection Agency

Events GuidebookExcessive Heat