EMP A C T 

Environmental Monitoring for Public Access 

& Community Tracking 
Disclaimer: This document has been reviewed by the U.S. Environmental Protection Agency (EPA) 

and approved for publication. Mention of trade names or commercial products does not constitute 

endorsement or recommendation of their use. 
EPA/625/R-02/011 

September 2002 

RISK COMMUNICATION IN ACTION: 


ENVIRONMENTAL CASE STUDIES


United States Environmental Protection Agency


Office of Research and Development


National Risk Management Research Laboratory


Cincinnati, OH 45268


250% Recycled/Recyclable 

Printed with vegetable-based ink on 

paper that contains a minimum of 

50% post-consumer fiber content 

processed chlorine free 
ACKNOWLEDGMENTS

Dr. Dan Petersen (U.S. Environmental Protection Agency [EPA], National Risk Management 

Research Laboratory) served as principal author of this handbook. Co-authors included Linda 

Stein, David Berol, Judy Usherson, and Adam Parez of Eastern Research Group, Inc., an EPA 

contractor. EPA would like to thank the following people for their input during the development 

of this handbook: 

John Barten, Suburban Hennepin Regional Park District (Lake Access project) 

Scott Hammond, Miami River Index Project 

Kevin Rosseel, U.S. EPA SunWise Program 

Chet Wayland, U.S. EPA AirNow Project 
CONTENTS


Page


CHAPTER 1	 INTRODUCTION: TOOLS FOR COMMUNICATING


ENVIRONMENTAL HEALTH RISKS TO THE PUBLIC. . . . . . . . . 1-1


CHAPTER 2 HOW TO USE THIS HANDBOOK. . . . . . . . . . . . . . . . . . . . . . . . . . 2-1


2.1 Road Map . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1


2.2 Frequently Asked Questions. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2-1


CHAPTER 3	 DATA VISUALIZATION AND DATA INTERPRETATION


TOOLS FOR ENVIRONMENTAL RISK


COMMUNICATION. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1


3.1 Introduction. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1


3.2 Data Visualization Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1


3.2.1 How Can Maps Be Used for Environmental


Risk Communication? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-1


3.2.2 How Can Color-Coding Show Environmental


Quality Conditions?. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-2


3.2.3 How Are Icons (or Images) Used in Environmental


Risk Communication? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-3


3.2.4 How Are Graphs Used to Show Time-Relevant 


Environmental Data? . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-4


3.2.5 Geographic Information Systems. . . . . . . . . . . . . . . . . . . . . . . . 3-4


3.2.6 What Are Simulations and How Are They Used


for Environmental Risk Communication? . . . . . . . . . . . . . . . . . 3-5


3.3 Data Interpretation Tools. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-5


3.3.1 What Are Environmental Indexes? . . . . . . . . . . . . . . . . . . . . . . . 3-6


3.3.2 Publications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-9


3.4	 What's the Best Way To “Get the Word Out”?—


Distribution Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3-10


iii 
CHAPTER 4	 CASE STUDIES: DEVELOPING AND USING


DATA VISUALIZATION AND DATA


INTERPRETATION TOOLS . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1


4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1


4.2 AIRNow Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1


4.2.1 Project History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-1


4.2.2 Effective Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-2


4.2.3 Key Accomplishments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-6


4.2.4 Lessons Learned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-7


4.2.5 Future Plans. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-8


4.3 The River Index Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9


4.3.1 Project History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-9


4.3.2 Effective Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-10


4.3.3 Lessons Learned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-16


4.4 Lake Access Project . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-16


4.4.1 Project Description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-16


4.4.2 Effective Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-17


4.4.3 Key Accomplishments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-23


4.4.4 Lessons Learned . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4-23


CHAPTER 5	 GUIDELINES FOR DEVELOPING AND USING DATA


VISUALIZATION AND INTERPRETATION TOOLS


FOR RISK COMMUNICATION . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5-1


REFERENCES 

iv 
1INTRODUCTION: TOOLS FOR 

COMMUNICATING ENVIRONMENTAL 

HEALTH RISKS TO THE PUBLIC 

Communicating environmental health risks to the public has increasingly become a responsibility 

of local and state officials and private groups involved in environmental monitoring. People have 

come to expect access to more information about local air and water quality, for example, and 

advances in environmental monitoring and computer technology (such as the Internet) have made timely—sometimes daily—communication of environmental conditions possible. The experiences of the U.S. 

Environmental Protection Agency (EPA), state governments, and some local governments and private 

organizations in providing such time-relevant environmental risk communication can help other municipalities, states, and private groups develop or expand their own local environmental risk communication 

programs. 

This handbook reflects the experiences of a variety of projects that have been part of EPA’s 

Environmental Monitoring for Public Access and Community Tracking (EMPACT) Program, which 

was active from 1996 to 2002. A key goal of the EMPACT Program was to facilitate the process of 

providing the public with time-relevant environmental information, including information on any 

health risks associated with certain environmental conditions. Achieving this goal involved helping 

communities identify and use effective ways to collect, manage, and distribute timely environmental 

and health risk information; it also involved sharing the experiences of various municipalities that 

have successfully accomplished these objectives. 

Local and state EMPACT projects have been involved in a variety of environmental monitoring and 

risk communication activities, such as air quality monitoring and beach, lake, and river monitoring. 

In the course of these activities, certain tools and combinations of tools have proven to be effective for 

environmental risk communication, particularly data visualization and data interpretation tools. Data 

visualization tools graphically depict, in this context, environmental health risks or environmental 

quality conditions. Data interpretation tools describe complex scientific concepts in relatively simple 

terms (as index values, for example); this can help people understand the potential health risks associated with exposure to certain environmental conditions (such as air pollution). Some projects have developed such tools on a national scale, and some of these tools are available “as is” or are easily adaptable 

for use by localities to report local environmental conditions. Examples include EPA’s AIRNow project 

for air quality and the EPA SunWise project on UV radiation exposure from the sun. Other tools were 

developed on a more regional or local scale; some of these tools could be adopted by other communities (such as beach flags indicating local water quality, or the use of color-coded indexes or maps). 

This handbook discusses a wide variety of data visualization and data interpretation tools that municipalities involved in EMPACT projects have used successfully in environmental risk communication 

programs. The handbook explains what the tools are and how they can be used, and also presents a 

number of case studies of projects using such tools. It also provides some basic guidelines for developing and using data visualization and data interpretation tools. EPA hopes that sharing this information will help other states and municipalities establish environmental risk communication programs 

and expand existing programs to incorporate timelier, more effective risk communication methods. 

INTRODUCTION 1-1
2HOW TO USE THIS HANDBOOK 

This handbook provides both general and detailed information on how to use a wide variety 

of data visualization and data interpretation tools for effective environmental risk communication. The handbook is intended for local and state officials, environmental groups, and 

others who are responsible for communicating environmental conditions and associated health risks 

to the public. The handbook is organized as described below. 

2.1 ROAD MAP 

Overview of data visualization 

and data interpretation tools, 

including maps, color-coding, 

icons, graphs, geographic 

information systems, 

simulations, indexes, and 

publications: see Chapter 3. 

Case study presentations of

three projects that have successfully incorporated many

different data visualization and 

data interpretation tools into 

their programs: see Chapter 4. 

Guidelines for developing and 

using effective risk communication tools: see Chapter 5. 

2.2 FREQUENTLY ASKED QUESTIONS 

Whether you are just beginning to consider developing an environmental risk communication 

program or are in the process of expanding your program, the following frequently asked questions 

may be useful. 

Q: What are data visualization and data interpretation tools, and why are they important? 

A: Data visualization tools present information primarily through images (such as maps, icons, 

and pie charts) rather than words. Data interpretation tools (such as indexes) describe complex 

scientific concepts in relatively simple terms. Both of these tools can be particularly powerful in 

communicating information about environmental quality conditions (such as water quality) and 

environmental health risks. 

Q: What is time-relevant risk communication? 

A: The term “time-relevant” refers to the goal of providing real-time (such as daily or near-daily) 

environmental information. Providing time-relevant information can be particularly important 

when one seeks to communicate environmental risks, because such risks depend on conditions 

(such as air or water quality) that can change each day. The Internet and other data visualization 

and data interpretation tools often make it possible to communicate environmental risk information fairly quickly. 

Q: What are some of the most effective ways to inform the public about environmental risks? 

A: According to the experience of some environmental risk communication projects, the most effective ways to disseminate environmental risk information may include establishing a Web site that 

displays a variety of data visualization tools (e.g., maps, color-coded charts), arranging for local 

news media to present your information, establishing a telephone hotline, and developing a collection of printed materials. Many other outreach methods may also be effective, such as setting 

up kiosks at strategic locations to distribute information (sometimes on onsite computers), giving presentations to local officials and others, and incorporating the information into school science curriculums. 

HOW TO USE THIS HANDBOOK 2-1 
Q: Why is it sometimes desirable to make special presentations to children, senior citizens, and people 

with certain health problems? 

A: Children, senior citizens, and people with certain illnesses are often uniquely sensitive to the 

kinds of environmental problem that time-relevant monitoring typically addresses, such as 

ozone pollution and UV radiation. Therefore, it is sometimes worthwhile to tailor special materials for these audiences, since their issues and concerns may differ significantly from those of 

the general population. 

Q: How can our program avoid jargon and complex language in the materials we develop on environmental risks? 

A: One solution is to use graphic images as much as possible to convey your message in your materials. When you need to use language, first think about the literacy and education levels of your 

audience, and then tailor your language so that it will be comprehensible to the vast majority of 

that audience. With some effort and good writing skills, it is usually possible to express a complex 

concept clearly and in relatively simple terms. Where literacy and education vary dramatically, you 

may want to develop several editions of your written materials for different reading levels. Also, 

focus groups and interviews with members of your target audience can play an important role in 

identifying any jargon or overly complex language. 

2-2 Chapter 2
some of these tools for environmental risk communication, check to see whether any data visualiz

tion or data interpretation tools already exist that can meet your needs or be modified to do so. 

Some municipalities and organizations have successfully used tools developed by other projects. 

Experience has shown that the most effective tools are simple to understand and use, provide 

consistent messages, and reflect a uniform system that aligns with or complements already existin

systems. For example, if you use color-coding, use colors that are commonly used, understood, a

associated with particular messages (e.g., green for “go,” red for “stop”). Also, your tools will be 

more effective if they can be adapted to fit a variety of presentation formats (e.g., Web sites, 

brochures, presentations) and the requirements of the media (e.g., print, television, radio). 

Section 3.2 describes a variety of data visualization tools, and Section 3.3 describes some import

data interpretation tools. Section 3.4 summarizes the ways that risk information can be distribut

to your audiences (e.g., the Internet, newspapers, television). The ways in which projects have 

developed and used several of these tools, often in conjunction with one another (e.g., a colorcoded index) are described throughout this chapter and in Chapter 4. 

3.2 DATA VISUALIZATION TOOLS 

In this handbook, data visualization tools are any graphic representation of data to communicate 

health risks or other aspects of environmental quality. Presenting data in a visual format can 

enhance your audience’s understanding of and interest in the data. Data visualization tools 

discussed below include maps, color-coding, icons, graphs, geographic information systems (GIS

and simulations. 

3.2.1 HOW CAN MAPS BE USED FOR 

ENVIRONMENTAL RISK COMMUNICATION? 

Maps are one of the most basic and familiar data visualization tools that can be used to commun

cate time-relevant environmental quality information for particular locations. A map showing en

ronmental quality data can be based on specific geographic information (as in Figure 3-1) or 

it can illustrate environmental quality conditions on a broader conceptual scale, as in Figure 3-2

If kept simple (e.g., clutter-free) and accompanied by a good key that explains the symbols it use

a map can be one of the easiest data interpretation and visualization tools to develop and/or use. 

Figures 3-1 and 3-2 below illustrate how one EMPACT project, the SunWise Project, has succes

fully used different types of maps in its risk communication efforts. SunWise staff developed the 

maps to be intuitive and consistent with other map-reporting systems, such as the EMPACT 

AIRNow map for ozone (see Chapter 4 for a discussion of the AIRNow project). Many other 

EMPACT projects have also developed and used maps (see Chapter 4 for examples). TheAIRNo

project, for example, uses animated maps that depict the formation and movement of ozone 

throughout the course of the day; the colors on the map change as the ozone concentrations 

change. 

DATA VISUALIZATION AND DATA INTERPRETATION TOOLS 
tal quality are available are generally easy to locate on 

the map, and a simple key explains the map’s numbering system and color-coding. The key also translates numerical UV Index levels into different colorcoded exposure categories of minimal, low, moderate, 

high, and very high exposure. See Section 3.3.1 for 

more information about the UV Index. Sources: U.S. 

EPA, 2002a (http://www.epa.gov/sunwise); U.S. EPA, 

2002b (http://www.epa.gov/oei); National Weather 

Service, 2002 (http://www.nws.noaa.gov). 

Figure 3-2. Daily UV Index contour map. This map 

shows another way to communicate UV exposure 

levels. Rather than indicating specific locations (as 

Figure 3-1 does), this map uses color-coded areas to 

identify UV levels in general regions of the country 

on a daily basis. Source: U.S. EPA, 2002a 

(http://www.epa.gov/sunwise). 

3.2.2 HOW CAN COLOR-CODING 

SHOW ENVIRONMENTAL 

QUALITY CONDITIONS? 

Like maps, color-coding is already familiar to many 

people, and thus its message can be easily understood. The use of color-coding to indicate “good” or 

“poor” environmental quality conditions (and ranges 

between those extremes) has been combined successfully with maps, graphs, indexes, icons, and other 

tools for risk communication. Appropriate choices of 

colors (and ranges of colors) can enhance a viewer’s 

understanding. For example, using generally universally known color-coding schemes, such as green to 

http://www.epa.gov/sunwise/uvindexmap.htm

Figure 3-2 

http://www.epa.gov/sunwise/uvindexcontour.ht

represent “go” (e.g., the air quality in a particular area today is good, with little or no risk) and 

to represent “stop” (e.g., the air quality in this location today is unhealthy, and people may exp

ence health effects) is recommended. 

3-2 Chapter 
Protection developed a system to express


dissolved oxygen levels, which serve as one


indicator of water quality. The colors


selected range from blue for excellent dis- http://www.dep.state.ct.us/wtr/lis/monitoring/hyaug01.jpg


solved oxygen levels that support marine


life to black for severely impaired waters with very low dissolved oxygen levels. Additional clearly


differentiated colors (green, yellow, orange, and red) indicate intermediate levels of water quality


conditions. Source: University of Connecticut, 2002 (http://www.mysound.uconn.edu/index.html).


3.2.3 HOW ARE ICONS (OR IMAGES) USED IN

ENVIRONMENTAL RISK COMMUNICATION? 

The term “icon” is used here in a very general sense to describe any visual cue, or image, that is


used to communicate information—anything from a physical placard (e.g., a beach closure symbo

or sign) to a symbol on a computer screen. Although words may added, an icon should ideally be

able to convey at least its basic meaning without relying on language. For example, the Charles


River/Boston Harbor project uses two icons, as shown in Figure 3-4, to indicate whether water


quality conditions in certain areas of the river or harbor are suitable for boating or whether health

risks exist. These symbols are used both on the program Web site and on actual flags that are pos

ed at boat houses along the Charles River. Another beach water quality program, the Southeastern

Wisconsin Beach Health Program, uses an icon of a swimmer and an icon of a crossed-out swim­

mer to indicate the concepts of open and closed swimming beaches (see Chapter 5 and


http://infotrek.er.usgs.gov/pls/beachhealth). Other examples of icons used to indicate environmental


quality or health risks are included in Chapter 4.


Figure 3-4. Icons used in beach flagging Figure 3-4


program. The Charles River/Boston Harbor


project uses different-colored flags with an


icon of a boat on its Web site (and actual


flags at various sites on the river, including


boat launches) to quickly and easily commu­


nicate water quality and health risks to recre­


ational water users. Blue flags indicate that


water quality conditions are suitable for


boating on the river, while red flags, with a


line through the boat, indicate potential


health risks from boating at a particular


place and time. Source: Charles River


Watershed Association, 2002


(http://www.crwa.org/wq/daily/2002/daily.html). 

http://www.crwa.org/wq/daily/2001/daily.html 

DATA VISUALIZATION AND DATA INTERPRETATION TOOLS 
Figure 35. Use of a graph to plot several water Figure 3

5


quality parameters. Using a “profile plotter”


application, users of the Lake Access project Web


site can choose from a number of different water


quality variables to plot, including temperature,


pH, specific conductance, dissolved oxygen, and


turbidity. This particular graph shows tempera­


ture, pH, and dissolved oxygen concentrations at


various depths in a particular lake at 4:00 a.m.


on October 22, 2001, in the form of a lake pro-


file line plot. Graphing these and other water


quality variables can reveal how water quality


changes over time and depth. Source: Lake


Access, 2002 (www.lakeaccess.org).


3.2.5 GEOGRAPHIC INFORMATION SYSTEMS 

GIS are effective data visualization tools for displaying, analyzing, and modeling spatial or 

geographic information. A GIS can be used to generate maps, animations, and two- and threedimensional models once detailed data are input into the system by skilled staff. (This process 

be labor-intensive and fairly expensive.) Two key advantages of GIS are that it allows users to 

quickly overlay and view several different data layers simultaneously, such as open-space lands, 

water resources, and population, and that it lets users view and compare different future scenar

(such as future land uses) and their possible impacts (e.g., on environmental resources). State e

ronmental agencies and private organizations are increasingly developing GIS maps that includ

environmental and related features, such as hydrology, land uses, zoning codes, soils, topograph

political boundaries, watershed boundaries, and transportation data. These maps may be readil

available for display and use, including through the Internet. Often users can retrieve informat

generate maps (including customized maps), and query data simply by clicking on a map featu

However, some GIS maps are relevant for only particular geographic locations. Once develope

GIS maps are relatively easy to use and understand by local officials and the public. Figure 3-6 

shows a color-coded GIS map that focuses on land uses and water quality. 

3-4 Chapter 
Access.) Source: U.S. EPA, 2000.


3.2.6 WHAT ARE 

SIMULATIONS AND 

HOW ARE THEY USED 

FOR ENVIRONMENTAL RISK COMMUNICATION? 

Some EMPACT projects, such as the Tulsa Air and Water Quality Information System, use game

like simulations to convey information about environmental risk. Tulsa’s simulation is entitled 

Smog City and is based on a model developed by the Sacramento Metropolitan Air Quality 

Management District (see Chapter 4). Smog City contains a variety of controls for which a number of factors affecting smog formation may be set, as shown in Figure 3-7. These factors include 

temperature, population, presence of inversion layers, and cloud cover. An animated rendition of 

Smog City changes to reflect the user’s settings. The output of the simulation is an imaginary plo

of the typical smog profile (more specifically, a plot of ozone concentrations throughout the day) 

for the simulated city. Although simulations do not convey time-relevant data about the state of 

the real world, they do convey principles and conditions that can be useful to people in their real

world decision-making. 

Figure 3-7. Tulsa’s “Smog City” simulation. 

When users select representative emission levels from 

sources including vehicles, industry, and consumer 

products, as well as weather conditions (temperature 

and cloud cover) and population level, a simulation of 

resulting smog (ozone levels) appears that reflects the 

conditions selected. Source: Tulsa Air and Water Quality 

Information System, 2002. 

3.3 DATA INTERPRETATION

TOOLS 

Data interpretation tools such as indexes translatecomplex scientific concepts into relatively simple systems 

that can facilitate the users’ understanding of technical 

Figure 3-7 

http://www.e-tulsa.org/smogcity/runsmogcity.ht

data and related health risks. This section mainly discusses indexes, giving examples of indexes us

by EMPACT projects. It also touches briefly on publications, a common and traditional commun

cation tool. 

DATA VISUALIZATION AND DATA INTERPRETATION TOOLS 
When you develop or use indexes, related color-coding schemes or other data visualization and 

data interpretation tools, you will often need to decide where “good” (or “low risk”) ends and 

“poor” (or “high risk”) begins, as well as how additional intermediate ranges are to be determin

These key junctures are “cutoff ” points that identify the important data ranges in the overall in

scheme. In the context of environmental risk communication, basing cutoff points and ranges 

scientific information is recommended whenever possible so that the index reflects actual risk l

(as is the case for many of the indexes discussed as examples in this chapter and Chapter 4). 

Index values and their meanings can be calculated and reported in a number of different ways, 

such as reporting the highest single number based on measurements of several different polluta

(as in the Air Quality Index discussed below); mathematically combining the ratings of differen

parameters into a single index value (as in the River Index described in Chapter 4); or expressi

the different index ranges as multiples or percentages of measurements or standards generally u

A number of EMPACT projects use indexes as key data interpretation tools for risk communic

tion, including the SunWise Program and the AIRNow project. These two projects’ use of ind

is described below; see also Chapter 4, which provides a detailed, step-by-step review of how th

River Index was developed. Some of these indexes might be directly applicable and useable for 

your location, such as the UV Index used by the SunWise program and the Air Quality Index 

by AIRNow. Other existing indexes might be useful if modified for your location or program 

objectives. The examples provided below and in Chapter 4 provide an overview of how environ

mental indexes are developed, what they are based on, and how they are used. 

3.3.1.1 THE EPA SUNWISE PROGRAM AND THE UV IND

The EPA SunWise Program uses the National Weather Service’s (NWS’s) Ultraviolet Index 

(or UV Index), which provides a daily forecast of the expected risk of overexposure to the sun. 

The Index predicts the next day’s UV radiation levels on a 0 to 10+ (up to 15) scale, where 0 i

cates a minimal likely level of exposure to UV rays and 10+ means a very high level of exposur

The higher the UV Index, the greater the dose rate (the amount of UV skin- and eye-damagin

radiation to which a person will be exposed), and the less time it takes before skin damage occ

(For more background information on the UV Index, visit 

http://www.cpc.ncep.noaa.gov/products/stratosphere/uv_index/index.html.) 

The NWS develops the UV Index by using a computer model to first calculate the UV dose ra

then adjust the result for important effects likely to influence this rate. For UV radiation, such 

effects include elevation and cloud cover at specific locations. The resulting value is the next da

UV Index forecast. The SunWise Program also allows users to enter their ZIP code to get a UV 

forecast specifically for that location. The UV Index used in the SunWise Program includes th

cutoff ranges listed in Table 3-1. 

3-6 Chapter 
Source: Climate Prediction Center, 2000 

3.3.1.2 THE AIRNOW PROGRAM AND THE AIR QUALITY INDEX 

The EMPACT AIRNow project uses the Air Quality Index (AQI) developed by EPA to commun

cate the level of health concern associated with different concentrations of certain air pollutants. 

The AQI ranges from 0 (“good” air quality) to 500 (“hazardous” air quality). The higher the Inde

value, the greater the health concern. 

The reported Index value reflects the single pollutant with the highest value. Exposure to multipl

pollutants is not reflected due to a lack of data on associated health effects. To facilitate risk communication, reporting of the AQI has shifted in recent years: instead of numbers, the colors with 

which the Index values are associated are reported. 

The AQI is divided into six color-coded ranges, as shown in Table 3-2. These correspond to the 

color scheme used in AIRNow’s ozone map (see Chapter 4). The use of uniform colors that are 

easily understandable by the general public to support a nationally uniform index was an important goal that was successfully achieved (though debate occurred regarding which particular color

to use). 

gg p

5 to 6 Moderate Use sunscreen if you work outdoors and remember to 

protect sensitive areas like the nose and the rims of the 

ears. Sunscreen prevents sunburn and some of the sun's 

damaging effects on the immune system. Use a lip balm 

or lip cream containing a sunscreen. Lip balms can help 

protect some people from getting cold sores. 

7 to 9 High Wear long-sleeved shirts and trousers made from tightly 

woven fabrics. UV rays can pass through the holes of 

loosely knit fabrics. 

10+ Very High Avoid being in the sun as much as possible. Wear 

sunglasses that block 99 to 100 percent of all UV rays 

(both UVA and UVB). Wear a hat with a wide brim. 

DATA VISUALIZATION AND DATA INTERPRETATION TOOLS 
Generally, the different AQI ranges (or cutoff points) are defined by different populations know

to exhibit noticeable health problems at these different ranges. (See the AIRNow case study in 

Chapter 4 for a more detailed discussion of the cutoff points and populations). Including Inde

ranges for sensitive groups provides useful information for these populations, while not alarmin

the general public (Stone, 2000). 

EPA used focus groups, discussions with state and local agencies and the news media, and pub

comment to help decide cutoff ranges and corresponding colors for the AQI. Some people sug

ed additional or different colors, shades, or categories than were finally selected. For fine partic

late matter (PM2.5), EPA lowered the cutoffs in response to public comment. Because the scie

ic basis for setting standards for particulate matter is not very precise, there was a legitimate rea

for the public to question where the lines should be drawn. Even the name of the index may b

important. For example, the AQI was previously called the “Pollutant Standards Index”; this n

was changed to the “Air Quality Index” because focus groups and others much preferred a nam

that reflected air quality rather than air pollution (Stone, 2000). 

3.3.1.3 IF YOU’RE CONSIDERING DEVELOPING OR 

USING AN INDEX... 

In choosing an index that would be a useful tool in your environmental risk communication 

efforts, consider what other organizations might partner with you in developing and launching 

index, think about the limitations of the index you are investigating (e.g., what it cannot comm

nicate), and decide whether that index meets the specific needs of your program. These factors 

discussed below. 

Partners. Working with other relevant organizations can be important when you seek to develo

or use an environmental index that meets your needs. For the UV Index, NWS has worked wi

EPA, the Centers for Disease Control and Prevention, meteorologists, health and medical prof

sionals, and the World Meteorological Organization to ensure consistency among different UV 

Indexes. For the AQI, EPA staff worked with state and local air agencies and regional organiza

for 2 years, attended many meetings and conferences nationwide, and held eight focus groups 

throughout the country. 

y 

Purple 201 to 300 Very unhealthy 

Maroon 301 to 500 Hazardous 

3-8 Chapter 
• Include as many key factors as possible in your index development process that could 

influence the results and accuracy of the index. If any important factors are not accounted 

for, let the user know what they are and how they might influence the index results. 

Communicate What the Index Does Not Do 

It may be important to communicate certain caveats about environmental indexes to the public. 

For example, the UV Index’s users are informed that because the Index is a forecast, it will not 

always be exactly correct (though it is very reliable, with an 84 percent accuracy rate to within +/-

2 percentage points). Also, users should be told if the index does not account for any potentially 

important factors. For the UV Index, the effects of air pollutants, haze, 

sensitivity

and surface reflection from 

snow, water, and sand are not included. These factors can result in higher actual UV exposure 

under these environmental conditions than the UV Index value indicates. In addition, the UV Index 

is not intended 

. 

for individuals who are very sensitive to the sun, such as people with lupus erythematosus or other sun-sensitive diseases, or people taking certain medications that result in sun 

• Determine the needed frequency of reporting of your index. For many projects, daily report

ing may be needed so that the public can use the information in a timely manner, but the fr

quency should also reflect realistic expectations. For example, for the AQI, reporting is 

required daily; however, “daily” is defined as a minimum of 5 days a week, since there is con

cern that some state and local agencies may not be able to provide AQI reports on weekends 

(Stone, 2000). 

• Solicit feedback from a broad audience during development of the index, including the public. Expect people to disagree about the semantics of what to call intermediate categories on 

the borderline between “good” and “poor.” For example, should there be one intermediate 

category? Two? Four? Bear in mind that you may never achieve complete consensus on index 

cutoffs and ranges. EPA has found that between 4 and 10 ranges are usually adequate to com

municate variability in environmental quality and health effects, based on a review of differe

countries’ use of indexes (Stone, 2000). 

3.3.2 PUBLICATIONS 

Almost all EMPACT projects develop and use publications to communicate their risk informatio

to the public or other more specific audiences. They use a variety of formats, such as pamphlets, 

fact sheets, handbooks, and flyers. While publications cannot provide time-relevant (e.g., daily) 

data, they do provide information about how to interpret the data and what associated health risk

from certain environmental conditions might be. Guidance for developing publications (as well a

other types of written text) appropriate for different types of readers is provided in Chapter 5. 

DATA VISUALIZATION AND DATA INTERPRETATION TOOLS 
• Meetings 

• Schools 

Then, choose one or more distribution methods that are likely to reach the most people in you

target audience. A Web site may be an excellent way to distribute your risk information if your 

audience is likely to have access to the Internet; if not, you might want to choose another distr

tion method in addition to, or instead of, a Web site. 

3-10 Chapter 
4CASE STUDIES: DEVELOPING AND USING DATA 

VISUALIZATION AND DATA INTERPRETATION TOOLS 

4.1 INTRODUCTION 

This chapter shows how three particular EMPACT projects have successfully used a variety of the 

data visualization and data interpretation tools discussed in Chapter 3, often integrating several tools 

into their programs. The AIRNow Project (Section 4.2) provides hourly air quality conditions and 

daily forecasts for many areas across the country using color-coded maps, an index, a telephone hotline, the media, and printed publications, among other tools. The River Index Project (Section 4.3) 

primarily uses an index system to report on the water quality of various river segments surrounding 

Dayton, Ohio, including an indication of whether river conditions are favorable for recreational 

activities. The River Index incorporates color-coding into its risk communication efforts to facilitate 

the public’s understanding of the index values. The discussion of the River Index also includes a 

detailed explanation of how the index was developed. 

The Lake Access Project (Section 4.4) uses color-coded maps, an index, charts, GIS, kiosks, and 

three-dimensional animation, among other tools, to provide near-real-time water quality information 

to different audiences, with information ranging from simple to more complex, as selected by the 

user. All of these projects rely in part on their Web sites, in addition to other tools, for effective risk 

communication. Understanding how these projects use this wide range of risk communication tools 

“in real life” will hopefully be useful to other projects that are considering developing or expanding 

their own environmental risk communication programs. 

4.2 AIRNOW PROJECT 

4.2.1 PROJECT HISTORY 

The AIRNow project, launched in 1998, offers daily air quality forecasts as well as real-time air quality 

data for over 200 cities across the United States in a visual, easy-to-understand format. AIRNow, serving 

as a central clearinghouse for data collected from state and local agencies, reviews the data for quality 

assurance and transfers the information to the public via its Web site, http://www.epa.gov/airnow. It also 

provides links to more detailed state and local air quality Web sites. The AIRNow project was initially 

funded by EMPACT and was developed in partnership with state and local air quality agencies. 

The AIRNow project collects data from existing local and state ozone monitoring networks. These networks are equipped with data loggers and modems that collect and transmit measurements to state host 

computers. In areas where ozone monitoring networks are not well established, special-purpose monitors are used. Each participating state agency’s host computer is linked to a central EPA database called 

the Data Management Center (DMC). The DMC manages and quality-checks the data and sends 

them out for use in making ozone maps, which are posted on the AIRNow Web site. 

The AIRNow project uses the AQI as one of its primary risk communication tools. Under the Clean 

Air Act, EPA is required to establish a nationally uniform index for reporting air quality. In 1976, EPA 

established the Pollutant Standard Index (PSI), which provided information on pollutant concentrations for ground-level ozone, particulate matter, carbon monoxide, sulfur dioxide, and nitrogen dioxide. 

In 1998, EPA adopted several important revisions to the PSI and changed its name to “Air Quality 

Index.” Other changes included providing uniform categories, colors, and descriptors for air quality; 

revising the ozone and particulate matter standards to address new scientific findings; and adding a category to characterize air quality deemed to be “unhealthy for sensitive groups.” Most significantly, the 

new AQI was useful as a forecasting tool, whereas PSI values had only been reported as historical data 

for previous days. 

CASE STUDIES 4-1
The development of the AQI and AIRNow coincided with the rapid growth of the Internet. This 

fortuitous timing enabled AIRNow tools to quickly become widely adopted for air quality risk 

communication. 

4.2.2 EFFECTIVE METHODS 

The AIRNow program successfully integrates several risk communication tools, including colorcoded geographic maps, an index, a recorded telephone hotline, and traditional printed materials, 

as shown in Table 4-1. These tools provide information that is relatively easy to understand for 

people with little prior knowledge about air pollution and its risks. The information alerts the 

public about air quality during the ozone season through a Web site with a memorable URL 

(http://www.epa.gov/airnow) and weather reporting by media outlets. The data are also used by local 

agencies. The following subsections describe some of the risk communication tools used by 

AIRNow, particularly the AQI and real-time ozone maps. 

4.2.2.1 THE AIR QUALITY INDEX 

The AQI serves as the foundation for AIRNow. It is a tool developed by EPA (see Chapter 3) 

to provide timely and easy-to-understand information on local air quality and associated health 

concerns. 

Table 4-1. Summary of AIRNow Communication Products 

Product/Event 

Still-frame and 

animated ozone maps 

Targeted Audience 

• General public 

• People with sensitivity 

to ozone exposure 

Data Interpretation and Presentation Tools 

Distribution Mechanism 

• AIRNow Web site; Web sites of state and local air 

pollution agencies 

• Television, via local weather broadcasts in a

handful of local markets 

The Air Quality Index 

(AQI)

• General public 

• People with sensitivity

to exposure to pollutants

covered by the AQI 

• AIRNow Web site; Web sites of state and local air 

pollution agencies 

• Newspapers 

Satellite forum 

Interactive AQI 

calculator 

AIRNow Web site

Various publications:

Air Quality Guide for Ozone, 

Guideline for Developing an 

Ozone Forecasting Program,

Guideline for Reporting of 

Daily Air Quality, Ozone and 

Your Health, and Report of 

Eight Focus Groups...1 

Other Outreach and Education Products or Information Dissemination Techniques

• General public 

• State and local air 

pollution agencies 

• State and local public

health agencies 

• State and local air 

pollution and public

health agencies 

• General public 

• People with sensitivity

to exposure to pollutants

covered by the AQI 

• General public 

Web Sites and Other Internet Applications

Publications

• AIRNow Web site 

• AIRNow Web site 

• Broadcast via EPA's Air Pollution Distance

Learning Network

• Internet 

1 U.S. EPA, 1999a-d, 1998.

4-2 Chapter 4 
The AQI converts raw measurements of the six pollutants regulated by the Clean Air Act (ozone, 

fine and coarse particulate matter, carbon monoxide, nitrogen dioxide, and sulfur dioxide) into a 

number on a scale of 0 to 500. The scale is subdivided into categories such as “good,” “moderate”, 

“unhealthy,” and “hazardous.” Converting the measurements involves using standard conversion 

scales developed by EPA, as described below: 

• The AQI value of 100, which is the upper bound of the “moderate” category, corresponds to 

health-based national air quality standards (the National Ambient Air Quality Standards, or 

NAAQS) established for each of these pollutants. These standards, and the corresponding 

Index value of 100, reflect scientifically peer-reviewed information on health effects. 

• The Index value of 50, which is the upper bound of the “good” category, is defined in one of 

three ways: (a) the level of the annual standard (if an annual standard has been established for 

that pollutant); (b) a concentration equal to one-half the value of the short-term standard 

used to define an Index value of 100; or (c) the concentration at which the risk to the public 

becomes very small (e.g., the 8-hour ozone average), and/or the magnitude of the health 

effects becomes highly uncertain. 

• Between the Index values of 100 and 500, a linear relationship generally exists between 

increasing values and increasingly severe health effects associated with pollutant levels. For 

example, the value for ozone of 150 (the upper bound for the “Unhealthy for Sensitive 

Groups” category) corresponds to an ozone concentration of 0.10 parts per million (ppm), 

based on a risk assessment conducted for the ozone NAAQS that indicated that this is the 

level at which exposures are associated with an increase in the number of individuals who 

could experience effects (including possible respiratory effects in the general population 

and a greater likelihood of respiratory symptoms and breathing difficulty in sensitive groups) 

(Stone, 2000). 

Originally, EPA based the AQI for ozone (the focus of the EMPACT AIRNow project) on a 1-

hour standard. Since 1997, the Index has been based instead on an 8-hour standard, because 

research has found that the original 1-hour standard was not adequately protective of human 

health. The 1-hour standard limited ozone levels to 0.12 ppm averaged over a 1-hour period; the 

new 8-hour standard requires that a community’s ozone levels be no higher than 0.08 ppm when 

averaged over an 8-hour period. 

An ozone measurement of 0.08 ppm (which is the NAAQS for ozone) corresponds to a “moderate” 

AQI value of 100 for ozone; carbon dioxide levels between 4.5 and 9.4 ppm correspond to “moderate” AQI values between 51 to 100. A similar measurement-to-index value conversion process is 

conducted for all six NAAQS pollutants individually; the highest individual pollutant value is then 

reported as the AQI for that local area for a particular day. Information may also be reported for 

any other pollutant with an Index value above 100. 

AIRNow associates each of the six AQI categories with a color (also used in ozone mapping), and 

the level of health concern associated with each AQI category is summarized by a descriptor. Table 

3-2 (in Chapter 3) outlines these categories and descriptors; Table 4-2 explains how they relate to 

the 1-to-500 scale. Table 4-3 explains what types of health effect are associated with each of the six 

categories and what individuals can do to avoid these effects. 

4.2.2.2 OZONE MAPS 

The AIRNow ozone maps present the AQI in a visual, easy-to-understand format. The maps use 

the categories and color scheme developed for the AQI and delineate geographic concentrations of 

ground-level ozone so that individuals can easily determine the quality of the air in their immediate 

vicinity. 

CASE STUDIES 4-3 
Table 4-2. AQI Color-Coded Index Ranges and

Risk Communication of Health Concerns 

Air Quality Index Range and Level

of Health Concern Communicated

Air Quality Index Rating

and Associated Color 

Good (green) When the AQI value for your community is between 0 and 50, air

quality is considered satisfactory in your area. 

Moderate (yellow) When the AQI value for your community is between 51 and 100, 

air quality is acceptable in your area. (However, people who are 

extremely sensitive to ozone may experience respiratory symptoms.) 

Unhealthy for sensitive 

groups (orange) 

Some people are particularly sensitive to the harmful effects of 

certain air pollutants. For example, people with asthma may be

sensitive to sulfur dioxide and ozone, while people with heart disease 

may be sensitive to carbon monoxide. Some groups of people may

be sensitive to more than one pollutant. When AQI values are between 

101 and 150, members of sensitive groups may experience health

effects. Members of the general public are not likely to be affected 

when the AQI is in this range. 

Unhealthy (red) When AQI values are between 151 and 200, everyone may begin to

experience health effects. Members of sensitive groups may 

experience more serious health effects. 

Very unhealthy (purple) AQI values between 201 and 300 trigger a health alert for everyone. 

Hazardous (maroon) AQI values over 300 trigger health warnings of emergency conditions. 

Such values rarely occur in the United States. 

Consider Focus Groups for Public Feedback 

In developing the AQI and ozone maps, EPA conducted a series of eight focus groups around the country 

which evaluated the effectiveness of these tools for risk communication. The groups 

were 

examined how effectively the map, cautionary statements, and an ozone health effects booklet (Smog—Who Does it Hurt?) 

conveyed information 

tested. 

to the general public and targeted audiences. Four different versions of the map 

4-4 Chapter 4
Table 4-3. Health Effects and Protection Measures 

Associated with AQI Categories 

CASE STUDIES 4-5
A Map Generator (MapGen) system produces both still-frame images of ozone concentrations, including hourly snapshots of data, and animated maps illustrating the movement of ground-level ozone over 

time. MapGen enables users to customize the maps based on their data and outreach needs. Users of 

MapGen can also customize maps to show supporting information such as geographic features, identifying text, and images. During the ozone season (May through September for most areas), the ozone 

maps are updated daily every hour. The software developed under this project is publicly available at no 

cost. Figure 4-1 shows an image composed using MapGen. 

Figure 4-1 

The map shows that ozone levels ranged from good 

to very unhealthy across the region 

Figure 4-1. Ozone map generated with MapGen. 

Source: U.S. EPA, 2002c (http://www.epa.gov/airnow). 

The AIRNow project is staffed by contractors and 

operates on a 24/7 basis. An automated quality control procedure processes reports that come in from the 

local, state, and EPA offices. Program staff also conduct additional quality assurance reviews of the data. 

A night staff ensures 24-hour-a-day accessibility of the 

system. AIRNow also has contacts at the state and 

local levels who provide technical support to fix problems with particular ozone monitors. The continuous 

monitoring provided by AIRNow obviates the need 

for local EPA offices to constantly check their ozone 

measuring instruments. 

Full implementation of the automated real-time ozone mapping system in the eastern United States 

began in 1998. The map will ultimately include all of the contiguous United States and feature additional pollutants (e.g., particulate matter). 

4.2.2.3 OTHER RISK COMMUNICATION TOOLS USED BY 

THE AIRNOW PROGRAM 

The AIRNow Web site includes an interactive AQI calculator that enables the user to convert ambient 

ozone concentrations (parts per billion or parts per million) to AQI values and vice versa. The 

AIRNow program also operates an online “WebBoard” that provides technical assistance and facilitates 

information sharing by program participants. The site posts question-and-answer sessions, contains a 

comprehensive search feature, and hosts a chat room related to ozone mapping. Off the Web, 

AIRNow provides conventional printed materials, such as fact sheets, booklets, and reports. 

4.2.3 KEY ACCOMPLISHMENTS 

Many innovative ozone outreach efforts have been implemented around the country using AIRNow 

communication tools. The project has placed a special focus on working with weather service providers 

for inclusion of the ozone maps in local television weather forecasts. The maps are also being used by 

local media in feature coverage of local and regional Ozone Action Day programs. AIRNow tools are 

also being integrated into science and health curricula, and are used for hotlines that provide recorded 

information about current and forecasted ozone levels. 

The AIRNow Web site gets over 3 million hits a month. On national cable television, The Weather 

Channel and CNN include AQI forecasts on their morning and evening weather forecasts during the 

ozone season and are working with EPA to make this a year-round information product. The Weather 

Channel’s Web site, http://www.weather.com, includes air quality forecasts on its health page every day, 

year-round. (Figure 4-2 shows an example of www.weather.com’s air quality information.) Also, the 

national newspaper USA Today publishes AQI information during the summer and is working to 

make this a year-round feature. 

4-6 Chapter 4 
Figure 4-2. The Weather Channel’s online air 

quality display. Source: Image courtesy of The 

Weather Channel, 2002 (http://www.weather.com). 

In addition to their widespread use in daily newspaper, television, and radio weather reporting, the 

AQI and other AIRNow products are the primary risk communication tools used in regional 

and local “Ozone Action Days” to inform the 

media and the public of health concerns associated with poor air quality. 

4.2.4 LESSONS LEARNED 

In developing and implementing AIRNow risk


communication tools, EPA and participating


state air quality programs have learned some


valuable lessons that have contributed to their success: 


Figure 4-2 

www.weather.com 

• It was important to get broad public feedback in creating and refining the AQI. Although 

achieving consensus is always desirable, the Agency learned that complete consensus was 

unlikely to occur. Semantic arguments were common, especially about defining or characterizing the “gray” areas on the borderline between “good” and “bad” air quality. 

• A positive (rather than negative) focus was found to be very important for effective risk 

communication. For example, EPA’s research showed that people overwhelmingly preferred 

the name “Air Quality Index” to “Pollutant Standards Index.” 

• EPA also learned that it is important to offer enough categories (e.g., 4 to 10) to display 

variability in air quality and health effects information. State and local air agencies are not 

required to display categories they do not use. 

• In refining the AQI, EPA learned the importance of keeping the Index as simple as possible, 

but consistent with the health message. 

• EPA also learned to use short, media-ready statements. This is the genesis of the sensitive 

groups statements (for example, for ozone: “children and people with asthma are the groups 

most at risk”). 

• It is important to use plain language (e.g., “unhealthy” rather than “unhealthful.”). (See 

Chapter 5.) 

• Developing an appropriate and intuitive color-coding scheme is vital in public risk education. 

AQI has become very well understood in just 2 years because the color scheme works so well. 

• In developing the AQI and AIRNow risk communication tools, it was (and continues to be) 

important to consider other contemporary visualization tools, such as weather maps, used by 

national print and broadcast media. 

• A lesson learned by the Sacramento Air Quality Management Division in getting ozone maps 

on television was the importance of cultivating strong working relationships with local broadcast meteorologists. In addition to pushing for broadcast of the maps, Division staff provided 

the meteorologists with information on all types of air quality issues, made themselves available to television station staff for their weather-related news and reports, and helped the stations develop feature stories. See the box below for more information on the Sacramento 

ozone mapping project. 

CASE STUDIES 4-7 
• The Texas Natural Resource Conservation Commission was able to render more accurate and 

timely maps by using 1-hour running averages. A high modem-to-monitor ratio also proved 

to be important in ensuring fast data transmission. See the box below for more on the Texas 

ozone mapping project. 

• In establishing its monitoring system, Texas learned that the density of the monitoring network is critical to producing useful and accurate ozone maps. Hence, the system uses one 

modem for every four monitoring stations. 

Sacramento Works the Media 

The Metropolitan Air Quality Management District (AQMD) in Sacramento, California, has successfully 

integrated AIRNow risk communication tools into local weather reports. AQMD has a long history of working with the region’s television meteorologists to familiarize them with the AQI and regional air quality 

issues. When ozone mapping became available in 1996, it proved to be a valuable new outreach tool. 

Since 1998, two Sacramento television stations have regularly aired AQMD’s animated ozone maps and 

forecasts during weather segments on the stations’ combined nine daily newscasts. AQMD has consistently sought feedback from the meteorologists to ensure that the maps serve their needs. AQMD’s Web 

site, http://www.sparetheair.com, provides animated ozone maps (“Ozone Movies”) that are updated 

hourly during the ozone season (May 1 through October 31). The local all-news radio station also regularly broadcasts air quality forecasts within weather and traffic reports. 

Source: Sacramento Metropolitan Air Quality Management District, 2002. 

4.2.5 FUTURE PLANS 

The AIRNow program is integrating new technologies into its risk communication tools. For 

example, EPA is working toward using a GIS map rather than standard maps for different metropolitan areas. The plan is to introduce a GIS map of the whole country that enables users to zoom 

in on a specific area. This will make it possible for each user to more easily localize the map and 

access more specific, local air quality information. 

4-8 Chapter 4
Timeliness and Accuracy in Texas

In 1994, the Texas Natural Resource Conservation Commission (TNRCC) upgraded its 20-year-old air 

quality monitoring technology. Of paramount concern was the need to provide accurate and immediately 

useful information to the public, especially during the ozone season, which is longer in Texas than in most 

other parts of the country. The new system purchased by Texas collects data every 5 minutes and transmits the data to regional hub computers. Every 15 minutes the hubs transmit data to the central office. In 

accordance with EPA rules, the central office averages 12 5-minute data reports to derive hourly averages. 

TNRCC is currently mapping southeastern Texas (covering the Houston, Galveston, and Brazoria region) 

and the Dallas/Fort Worth area, and will start mapping El Paso during the summer of 2002. TNRCC is 

working with the government in Ciudad Juarez, Mexico, to include monitoring on that side of the border 

and anticipates that the El Paso map will be bilingual. 

In creating ozone maps from the data collected, TNRCC uses 1-hour running averages to improve the presentation of air quality changes over time. TNRCC is widely recognized as providing some of the fastest 

(and therefore most accurate) real-time air quality updates among participants in the AIRNow program. 

Source: Texas Natural Resource Conservation Commission, 2002. 

4.3 THE RIVER INDEX PROJECT 

4.3.1 PROJECT HISTORY 

The Miami Valley River Index Project, one of EMPACT’s 

MetroGrant programs, provides time-relevant water quality 

information on some of the rivers and creeks surrounding 

Dayton, Ohio. Before the project began, there was little public awareness of the Dayton area’s watershed. What public 

awareness did exist tended to be unduly pessimistic about the 

Photo courtesy of Miami River Index environmental condition of the Miami Valley’s waterways. 

(Dayton, Ohio) The River Index program was founded in 1998 as a way to 

improve public knowledge about the condition of these 

waterways and thus make them more accessible to recreational use. Some of the water-related 

recreational activities that the Dayton-area public now engage in include canoeing, fishing, and 

bicycling along the river shorelines. 

CASE STUDIES 4-9
Official work on the River Index Project proceeded in January 1999 as a collaboration between 

many different partners: the Miami Valley Regional Planning Commission, the Miami 

Conservancy District, the consulting firm CH2M Hill, Inc., the City of Dayton, Wright State 

University, the Yellow Spring Instrument Company, and the U.S. Geological Survey. The River 

Index Project has collected data from six Dayton-area automated monitoring sites over the last 3 

years (1999, 2000, and 2001). The project’s data collection season runs for the period of time in 

which the public is likely to make use of the rivers—roughly from the beginning of summer 

through early fall. 

4.3.2 EFFECTIVE METHODS 

4.3.2.1 OVERVIEW OF THE RIVER PROJECT INDEXES 

An innovative risk communication tool of the River Index Project is its indexing system, which 

synthesizes a wide array of water quality data. The indexing system converts measurements into a 

single, easy-to-understand rating, which is disseminated to the public on the Web site 

http://www.riverindex.org. 

A key concern for the River Index Project as it developed its index and other risk communication 

tools was that the tools meet, and be perceived as meeting, the highest professional and scientific 

standards. Yet generating a river quality index involved making judgement calls about where to set 

cutoffs between different categories of environmental quality (i.e., between “excellent” and “good” 

river quality). Also necessary were judgement calls about how to weight and combine an array of 

dissimilar measurements into a single measurement of river quality. To this end, the River Index 

Project recruited eight internationally recognized water quality experts to serve on a review panel 

that supervises the project’s activities. 

Drawing on their own expertise and that of a peer review panel, the staff of the River Index Project 

developed two indexes to convey information about local rivers: 

• A water quality index, which synthesizes and summarizes information about the following 

river water measurements: 

- Dissolved oxygen - Specific conductivity 

- E. coli - Temperature 

- pH 

• A river index, which includes all the parameters of the water quality index plus two additional 

physical parameters: 

- Flow rate 

- Turbidity 

While the water quality index focuses on those issues pertaining to the health of the river ecosystem, the river index provides a broader sense of whether conditions are right for recreational use of 

a river. Flow rate is a particularly important parameter for determining river safety. A very high 

flow rate not only indicates strong, potentially dangerous currents, it warns of possible flooding. 

For the sake of safety, the river index is set up to automatically take the “poor” rating (regardless of 

how good the other parameters are) if flow rate approaches a level characteristic of flood activity. 

Under these circumstances, the River Index Web site also displays a special flood warning. 

4.3.2.2 COMMUNICATING THE INDEX 

General vs. Specific Ratings. The River Index is a mathematical procedure for “rating” a stretch of 

water in terms of its current suitability for recreational pursuits. The system does not specify which 

particular recreational activities are likely to be safe or advisable—it simply states whether or not 

4-10 Chapter 4 
the river conditions are favorable for recreation in general. The developers of the River Index 

originally considered issuing use-based advisories (e.g., the river is or is not safe for boating, swimming, fishing, etc.) but ultimately decided against this strategy because they felt it called for overly 

subjective judgements and exposed the project to an undesired level of legal liability. It remains the 

responsibility of individual users to make their own judgments about whether or not a particular 

river activity is wise. The River Index Web site also provides the raw data upon which its general 

rating was founded, which may help the user make such decisions. 

River Index Maps and Icons 

On the main page of its Web site, the River Index Project displays a schematic map of the Miami River 

Valley, centered on the city of Dayton, Ohio. The purpose of this map is to provide an “at-a-glance” summary of water quality for all the rivers covered by the project. The most prominent features of the map are 

the area’s rivers and streams, colored light blue. Certain river segments are labeled on the map. The 

background color of each segment’s label changes to match the river’s current water quality index—a key 

on the map reminds the viewer of what each color means. The map also displays the boundaries of local 

counties. 

One prominent feature of this map is the cartoon-like icon of a “happy fish.” The happy fish serves as a 

navigational icon and a recurrent design element throughout the Project’s Web site. On various other 

pages of the Web site, there are small, click-able icons of happy fish that return the user to the River Index 

home page. This iconography not only makes it easier to refer back to the summary map, but also gives 

visual and thematic cohesion to the entire Web site. 

Source: River Index Project, 2002. 

What the Ratings Mean. Each of the six monitoring sites may have a different river index “rating,” 

depending on how many points have been assigned to it in the indexing process. Table 4-4 summarizes the different ratings. 

CASE STUDIES 4-11
Table 4-4. Rating System Used in the River Index 

Rating Number of 

Total Points Meaning 

Excellent 32–40 "Overall measurements indicate high water quality. 

Conditions highly favorable for recreation." 

Good 25–31 "Most measurements meet or exceed Water Quality Standards. 

Conditions favorable for recreation." 

Fair 18–24 "Some measurements meet or exceed Water Quality Standards. 

Conditions marginally favorable for recreation." 

Poor 11–17 "Measurements indicate some water quality problems. 

Conditions generally not favorable for most recreation." 

Color-Coded Index Ratings. Each of the index ratings is paired with a color. Table 4-5 summarizes 

the color relationships used by River Index and their cultural connotations. The color scheme chosen by the River Index Project amplifies and coincides with the explanatory text for each rating. 

This is particularly important because some people may not bother to read and/or think about the 

carefully crafted text (included in Table 4-4) that explains each rating. These people may simply 

note the color of the rating and make their conclusions about the river based on their intuitive 

understanding of that color. Other people might read the explanatory language but be confused 

about its practical significance (e.g., about the difference between “favorable” and “highly favorable”). The cultural connotations of a color help to communicate the level of risk reflected by the 

different ratings. 

Table 4-5. Color-Coding System Used in the River Index 

Rating Color Cultural Significance of Color 

Excellent Green In traffic signals, the green light says "go ahead." Similarly, this rating 

entices the index user to "go ahead" and use the river for recreation. 

Green also connotes environmental well-being. It suggests that the river 

is not only good for recreation, but also ecologically healthy. 

Good Blue Unlike the other three colors, blue is not used in traffic signals. "Good" 

therefore lacks the directive impact that the other ratings possess. 

In aesthetic terms, however, it is widely accepted as the normal color of 

water. Even though "good" is not the best possible rating, the color blue 

reassures the index user that the water is still clean and safe. 

Fair Yellow Yellow is the caution light in traffic signals. Without forbidding passage, 

it exhorts the viewer to exercise discretion and maintain a heightened 

state of awareness. Similarly, a yellow rating encourages the River Index 

user to think twice about his or her plans for using the river. The color 

encourages the user to learn more about the specific nature of the river's 

problems. 

Poor Red In traffic, the color red commands the viewer to stop. In an 

environmental context, it also conveys an impression of danger, 

emergency, and authority. The color red anchors "poor" at the bottom 

of the ranking system and it indicates that there is, at present, a serious 

problem with the river. The color encourages users to avoid the river 

altogether until the situation improves. 

4-12 Chapter 4
Averaging Index Values. Since some of the factors that contribute to the calculation of the river 

index change hourly, the river index itself must be updated frequently. It is updated every 8 hours, 

using an average of the previous 8 hourly automated readings and the most recent manual readings. Web site visitors can “drill down” to the most recent automated readings from the monitoring 

stations if they wish. One reason for updating the index only every 8 hours (rather than hourly) is 

to prevent it from fluctuating in a seemingly random and confusing manner. It is conceivable that, 

depending on the value of particular water parameters, the river index might be on the borderline 

between two different readings—for example, “good” and “fair.” If the index were updated every 

hour, insignificant variation (i.e., “noise”) in a river’s water quality parameters might cause its rating to flip-flop between good and fair. This phenomenon might undermine public confidence in 

the index’s reliability. This pitfall is avoided by reliance on averaged data, which are more likely to 

reflect significant changes in water quality. 

Another Data Visualization Tool: Dials 

Before the widespread use of digital readouts, scientific instruments typically presented their readings 

by means of analog dials. In automobiles, these dials remain the principal technology for communicating real-time information (e.g., speed, RPMs, oil pressure) to the driver. Thus, for many people the 

idea of reading a value off of a dial is quite intuitive. 

In the River Index Project, each dial has four sections, one for each of the four ratings. The needle of 

the dial always points to the middle of a section of the dial. All the sections of the dial are labeled (poor, 

fair, good, excellent) but only the one that the needle is pointing to is “lit up” with color. These dials 

do not represent continuous variation in index values: since the needle simply “jumps” from one state 

to the next, the dial would not distinguish between a “good” rating that was very close to “fair” and 

one that was very close to “excellent.” An interested user could make this distinction by looking at the 

actual numerical score for the index; but the fact that the dial does not visually distinguish between 

different scores within a single rating might convey the message that the distinction is unimportant. 

http://www.riverindex.org 

4.3.2.3 CALCULATING THE RIVER INDEX 

Except for the special case of flood danger, the procedure for determining the River Index is 

described below. 

Step 1: Rate individual water quality parameters. Each of the water quality parameters that contribute to the River Index can have a different value. The River Index rates these parameters as 

either poor (1 point), fair (2 points), good (3 points), or excellent (4 points). 

Let us take the case of dissolved oxygen as an example. According to Ohio EPA regulations and 

the judgement of several water quality experts, dissolved oxygen levels greater than 9 milligrams per 

liter (mg/l) are “excellent,” levels between 5 and 9 mg/l are “good,” levels between 2 and 5 mg/l are 

“fair,” and any value below 2 mg/l is “poor.” Therefore, a reading of 5.6 mg/l of dissolved oxygen 

would translate into 3 points, as shown in Table 4-6. 

CASE STUDIES 4-13
Table 4-6. Example of Rating System for

Individual Water Quality Parameters 

Dissolved Oxygen Level (mg/l) Parameter Rating 

> 9 Excellent (4 points) 

5–9 Good (3 points) 

2–5 Fair (2 points) 

< 2 Poor (1 point) 

Rating Parameters Are Based on Science 

For pH, for which a central value is the best and extremes on either end are poor, the River Index splits 

the pH parameter into an upper and lower range. Above pH 7, a lower pH garners more points; below pH 

7, a higher pH garners more points. 

Thus, valuation may be different for different parameters, based on scientific information. For dissolved 

oxygen (DO), an “excellent” rating of 4 is based on DO levels > 9, since the higher the DO level, the better the water quality. For pH, an “excellent” rating of 4 is based on pHs between 7 and 8, since a pH above 

or below this range is either too acidic or too basic. 

Range Excellent 

(4 points) 

Good 

(3 points) 

Fair 

(2 points) 

Poor 

(1 point) 

Upper (pH>7) 7–8 8–8.4 8.5–9 > 9 

Lower (pH<7) 7–8 6.5–7 6–6.4 < 6 

Step 2: Weight and add the point values of the different parameters. On a basic level, the next step 

involves simply adding up all the different points from the different water quality parameters. The 

advantage of the point system is that it puts the parameters in a standardized form—there are only 

four possible values per parameter, and the larger the sum total, the better the water quality. 

An element of complexity is introduced, however, when one acknowledges that not all the water 

quality parameters are equally important to the final quality of the river. To resolve this complexity, 

the River Index staff developed a system for weighting points assigned to different parameters, as 

shown in Table 4-7. The point value obtained in Step 1 for each parameter is multiplied by that 

parameter’s weighting factor to arrive at the final score for a particular parameter at a specific time 

and place, which will range from a minimum score of 11 to a maximum score of 40. In other 

words: 

Point value of each parameter × weighting factor for each parameter = final value for each parameter 

4-14 Chapter 4
Table 4-7. Weighting Factors Used To Indicate

the Relative Importance of Parameters 

Parameter Weighting Factor 

Dissolved oxygen 3 

E. coli 1 

pH 1 

Specific conductivity 1 

Water temperature 1 

Flow 2 

Turbidity 1 

Thus: Total point score for river water quality = (dissolved oxygen value × 3) + (E. coli value × 1) + (pH value × 1) + 

(specific conductivity value × 1) + (water temperature value × 1) + (flow value × 2) + (turbidity value × 1) 

Step 3: Assign a final rating based on the total score from the individual parameters. There remains 

the task of assigning a river segment a “poor,” “fair,” “good,” or “excellent” water quality rating, 

based on its total point value. Table 4-8 shows the cutoff ranges used in the River Index that 

correspond to these water quality ratings. 

Table 4-8. Overall River Water Quality Rating

and Corresponding Cutoff Ranges 

Water Quality Rating Cutoff Ranges (Points) 

Excellent 32–40 

Good 25–31 

Fair 18–24 

Poor 11–17 

One important caveat about the River Index’s rating system is that it has a limited ability to convey 

information about extreme deviations from the norm in any particular parameter. Say, for example, 

that a river somehow became extremely acidic (e.g., pH 4). Out of a possible 40 points, the river 

would lose 3 for the low pH. If all the other water quality parameters were in reasonable shape, the 

final rating for an acidic, nearly lifeless river would be “excellent.” 

This of course, is a highly unlikely scenario since there is no practical reason why the pH of a river 

near Dayton would suddenly drop in such an extreme fashion. The scenario merely serves to 

demonstrate the logical limitations inherent in an empirically weighted, linear indexing system. As 

mentioned earlier, the River Index Project has addressed this limitation by instituting a safety override to prevent extremely high flow levels from getting “hidden” in the index’s scoring process. Any 

organization developing a similar data interpretation tool in another context should consider 

whether that tool’s parameters could range to plausible extremes beyond which the tool would 

cease giving reasonable output. 

CASE STUDIES 4-15
4.4.3 LESSONS LEARNED 

The River Index Project has been successful in disseminating its daily river ratings through the 

media as well as its Web site. Local newspapers ran stories about the project and some listed the 

daily index on their weather page. Several television weather reports expressed some interest in displaying river quality information, but the nature of TV reporting made this somewhat difficult 

(e.g., TV weather reports would prefer to receive river index information as an immediately available, “prepackaged” video signal). Weekend TV weather reports did include the river index as a 

recreational advisory. 

Feedback from the public was modest but almost always positive. Anglers, in particular, were a 

major audience for the information. The employees of a nearby vehicle manufacturing plant took a 

particular interest in monitoring the quality of nearby rivers. The River Index Project sponsored a 

pre-survey and a 2-year progress survey of their target audiences’ knowledge of river conditions. 

These surveys, conducted using random phone interviews, revealed that audience awareness of 

Dayton’s rivers has increased slightly over the time period in which the River Index Project operated. However, the survey did not reveal widespread awareness of the River Index Project or the 

indexes themselves. This was the case in spite of the fact that the river indexes had been 

announced in the area news media, advertised on buses, and incorporated into a professionally 

designed Web site. In hindsight, the staff of the River Index Project concluded that they should 

have employed a marketing expert when they first presented the river indexes to the public. They 

felt that the project would have benefitted from more extensive “brand-building” to increase public 

awareness and media interest in it. The River Index Project continues to evaluate and revise its 

program to make it more meaningful and cost-effective. 

4.4 LAKE ACCESS PROJECT 

4.4.1 PROJECT DESCRIPTION 

The Lake Access water quality monitoring project was initiated in the state of Minnesota to deliver 

near-real-time data to a variety of audiences. The project aims to provide public officials, scientists, 

and the general public with information that will help them make sound decisions regarding water 

quality issues. The project team developed a series of data visualization tools that present scientific 

measurements in easy-to-understand formats such as charts or three-dimensional images. These 

tools allow data that were once available to and used mainly by scientists to be accessible and useful to the general public. 

The Lake Access team developed interactive data presentation tools with the goal of giving users 

control of the data. The different audiences for Lake Access data have different specific needs and 

interests. For example, a public official might be interested in determining the effects that phosphorus contamination from fertilizers have on local lakes, while a fisherman might be interested in 

knowing the oxygen content in certain areas of a lake to help determine where fish will most likely 

be located. Thus, the Lake Access project made many of its tools “user-controlled” (see Chapter 5) 

to allow more flexibility in manipulating and presenting data. 

The project team uses Remote Underwater Sampling System (RUSS) devices to collect time-relevant information from four locations in Minnesota. RUSS units collect data on five water quality 

variables: 

• Conductivity: The amount of dissolved salts, or ions, in water. 

• Turbidity: An indication of how clear the water is. 

4-16 Chapter 4
• Dissolved oxygen: A certain amount of oxygen is necessary for the survival of aquatic 

organisms. 

• Water temperature. 

• pH: In water, the pH level determines the solubility and availability of chemical constituents, 

including heavy metals. 

These RUSS units are also used in lakes elsewhere in the country. The Lake Access project aims to 

work with these other monitoring programs, such as those at Lake Onondaga in Syracuse, New 

York; Lake Washington, Seattle; and elsewhere in Minnesota. The project team also collects other 

types of information from additional monitoring stations, and integrates the non-RUSS data with 

the RUSS data. 

The Lake Access project is a cooperative effort of the Suburban Hennepin Regional Park District; 

the Minnehaha Creek Watershed District; the University of Minnesota Water on the Web 

Investigators (i.e., the Natural Resources Research Institute, the University of Minnesota-Duluth 

Department of Education, and Minnesota Sea Grant); and Apprise Technologies, Inc., which holds 

the license to RUSS technologies. Many of the key features on the Lake Access Web site, such as 

the data visualization tools, were developed under a grant from The National Science Foundation’s 

Advanced Technology Education Program. 

4.4.2 EFFECTIVE METHODS 

The Lake Access project’s data visualization and interpretation tools include color maps, charts, 

and three-dimensional animation to convey and manipulate water quality profiles collected by 

RUSS units and from manual sampling. Although these tools are designed to work with data generated by RUSS technology, they could also be set up to work with data collected from different 

monitoring systems in other communities. The Lake Access project team also uses the Carlson 

Trophic State Index to rate water quality. A summary of the data visualization and interpretation 

tools developed or used by Lake Access is shown in Table 4-9, and some of the tools are discussed 

below. 

Some of the Lake Access data visualization and interpretation tools deliver numerical data (Lake 

Access Live) or offer users simple graphs and charts created in Microsoft Excel. Others offer more 

sophisticated tools, such as GIS, that allow users to manipulate data. Most of the tools use color 

and graphical interfaces to enable users to “see” the information. 

4.4.2.1 CARLSON TROPHIC STATE INDEX 

The Lake Access project uses the Carlson Trophic State Index, which measures a water body’s 

eutrophication—the process by which lakes are enriched with nutrients, which increases the 

production of aquatic plants and algae, removes oxygen, and diminishes water quality. The Index, 

which is used by many organizations to set water quality goals, combines various measurements 

(e.g., transparency, phosphorus concentration) into a rating of water quality that ranges from 0 

to 100 (0 indicates clear water; 50 to 60 indicates mild concentration of nutrients, decreased 

transparency, and “threatened” quality; and 100 indicates algal scums and summer fish kills). 

CASE STUDIES 4-17
Table 4-9. Summary of Lake Access Data Visualization

and Data Interpretation Tools 

Data visualization tools 

(DVToolkit includes Profile 

Plotter, Color Mapper, and 

Depth Versus Time Profiler)

Lake Access Live: near-realtime display of numeric data; 

Profile Plotter; Color Mapper; 

Depth Versus Time Profiler 

• Explore lake data as they vary with depth and 

over time. 

• Create animated water quality profiles. 

• Feed real-time data to Web site. 

• Investigate correlations between water quality 

variables and trends. 

Tool Group Tools Primary Uses

Geographic information 

systems (GIS) 

Several, including ArcInfo; 

ArcView; GeoMedia; and 

MapInfo Professional 

• Integrate and model spatial data (e.g., water quality 

and land use). 

• Develop Internet mapping applications. 

Data interpretation tool Carlson Trophic State Index • Measure lake quality with a single index. 

Lake Access Web Site Color maps; charts; 

DVToolkit; GIS maps 

• Interactive capabilities to develop custom maps. 

Spreadsheet programs Microsoft Excel; Lotus 1-2-3 • Display raw data. 

• Investigate correlations between water quality 

variables and trends. 

• Create summary graphs of data. 

The Lake Access Web site (described below) shows the data in sample color-coded graphs. For 

example, blue represents clear water, while green indicates degrees of eutrophication. For water 

quality between 40 and 45, a light green shade is visible, and at 80, the shade is dark green. The 

site provides an in-depth discussion of the Index, and lets users access Index information for the 

four Minnesota lakes showcased in this project. 

4.4.2.2 LAKE ACCESS WEB SITE 

The Lake Access Web site (http://www.lakeaccess.org) is the project’s primary avenue of disseminating 

information through visually interactive tools (e.g., color maps and charts of temperature and pH levels 

in lakes). The site’s design features a rolling banner that presents time-relevant data from RUSS units in 

three lakes, as shown in Figure 4-3. The site also features a history page about one of the lakes, providing the user with background on the many influences that have affected the lake over time. 

Figure 4-3. The Lake Access Web site’s front Figure 4-3 

page for lake data. Visitors to the Web site


can access the tools available through the


Internet or they can download the


DVToolkit. With the DVToolkit saved on


his or her hard drive, the user can open the


data tools in a Web browser without having


to connect to the site. Users must download


the kit again if they want to access updated


information. The Lake Access team updates


the DVToolkit whenever it receives new


RUSS data. When using the toolkit online,


the user receives near-real-time data via the


Water on the Web server (http://wow.nrri.umn.edu/wow/).


It may take a while to load these data, but the toolkit runs quickly once they are loaded.


4-18 Chapter 4 
In addition to the interactive toolkit, the site offers users an interactive GIS mapping feature, with maps 

showing land use and land cover, as well as information on soils, roads, political boundaries, and other 

data layers that can be used in conjunction with the water quality data, such as the graph shown in 

Figure 4-4. 

Figure 4-4. Water Quality Trends. Graphs can be very useful data visualization tools—for example, 

to indicate trends over time. The graph above shows average pH values in the surface layer of Lake 

Independence, part of the Lake Access project, over time. The vertical bars over the data points 

represent the range of values measured for a particular day. Source: Lake Access, 2002. 

Communicating Information to Specific Audiences 

The Lake Access Web site is organized to present data to four distinct groups: swimmers, boaters, 

anglers, and land owners. For different users, the site offers different information that varies from simple to complex. For example, if users click on the “Swimmers” link, the site takes them to a page that 

shows the water temperature for Lake Independence, explains the risks of exposure to certain types 

and levels of bacteria, and describes the illness “swimmer’s itch.” For fishers, the link takes users to 

a page depicting the oxygen concentrations in Lake Minnetonka, Halstead Bay. Data are presented in 

color graphs, in which green indicates ample oxygen, and black or darker colors represent areas of 

depleted oxygen. 

The “Lake Data” section of the site provides more complex information and leads users to the 

DVToolkit. The section explains how RUSS data are collected, tells how the team ensures the quality 

of the data, and provides a link to EPA’s guidance on quality assurance measures. The “Lake Data” 

section also explains important terms, such as conductivity, dissolved oxygen, pH, and turbidity. 

Use of Color Coding. The DVToolkit, as well as the Excel-based graphs and charts, uses color to 

help convey the data to the user. For example, the Color Mapper uses intuitive colors that range 

from blue (to indicate cold) to red (to indicate hot) when measuring lake temperature, and colors 

ranging from green (for “good”) to black (for “poor”) when measuring oxygen concentration. 

Intuitive colors make it easier for users to understand data. For example, when using the Color 

Mapper, users can see changes in oxygen concentration in the background color. When oxygen 

concentration reaches 5 on the Color Mapper, the color fades to brown, then to blue when the 

CASE STUDIES 4-19 
concentration reaches 3, then to black. For temperature, the color is blue until about 10 degrees 

Celsius, after which it turns green, then yellow at 20 degrees Celsius, and finally red at 25 degrees 

Celsius. These colors function the same way on the Depth Versus Time (DxT) Profiler and most 

other Lake Access data visualization and interpretation tools. 

The only tool that deviates from these color codes is the Profile Plotter, which features the six Lake 

Access variables as lines plotted on a graph. Each category is assigned its own color, and these colors do not represent changes in data, only the category itself (e.g., temperature). Figure 4-5 shows 

examples from the Profile Plotter and Color Mapper. 

Figure 4-5. Screens from the Lake Access Profile Plotter and Color Mapper. Source: Lake Access, 2002. 

4.4.2.3 ANIMATION 

Lake Access also employs sophisticated animation and two- and three-dimensional graphics to convey water quality information to the public. Animation techniques are powerful visualization tools 

to help individuals understand technical data. The Lake Access Profile Plotter conveys water quality over time. Users can animate the profiles to see daily, monthly, and annual changes. The Color 

Mapper conveys the same information using a different graphical method: while the Profile Plotter 

uses color-coded line graphs with multiple lines designated by the user, the Color Mapper uses a 

single line with a color-coded background that represents another variable, allowing the user to 

understand the correlation between two different variables (such as pH and temperature). The 

Color Mapper can also be animated to show how the data change over time. 

4.4.2.4 TWO- AND THREE-DIMENSIONAL VISUALIZATION 

The Lake Access team wanted users to be able to display and analyze data in two or three dimensions. Accordingly, the DxT Profiler allows users to select a time period and a variable (such as 

oxygen concentration) and allows them to add grid lines, show the actual data points, and interpolate data by depth and time, as shown in Figure 4-6. This kind of flexibility in mapping information allows users to create sophisticated analyses of water quality data. In addition, the tool is used 

to create image files of the graphs for the Lake Access Web site. 

The Lake Access project also uses movie files to display data. Many Web sites use movie files (e.g., 

MPEGs, AVIs) to showcase video clips of items such as movies and news programs, but movie files 

can also be used to animate data. This unique method for displaying and conveying data is 

extremely useful for demonstrating how lake temperature changes throughout the year. By using a 

combination of color, motion, and easy-to-understand charts, the animation provides users with a 

good idea of where and when lake temperature is affected. 

4-20 Chapter 4 
The Lake Access team created an AVI animation of a chart depicting the change in lake temperature 

over time. The animation starts off with an image of a lake moving along the X axis of a chart, with 

the X axis representing time and the Y axis representing the lake’s depth. The dates displayed change 

as the picture moves along the X axis, as does the color of the lake. The user can see how the water 

nearer the surface heats up during the summer months (and that the temperature at the lake bottom 

remains relatively unchanged), and how the entire lake reaches a uniform temperature in the winter 

months. A question mark appears in the lower portion of the image to indicate periods in which no 

data were collected. Once the image reaches the end of the axis, it becomes a three-dimensional 

image displaying the lake’s various temperatures, as well as lake depth. It then rotates into the DxT 

plane, linking the animation to the output of the DxT Profiler and displaying a profile of the lake’s 

temperature change over time. 

Figure 4-6. Example of Lake Access three-dimensional lake cross-section × time animation. Source: 

Host et al., 2000. 

4.4.2.5 GEOGRAPHIC INFORMATION SYSTEMS 

GIS maps provide power and flexibility in using data. At the Lake Access Web site, under “Land 

Use/GIS,” users can see multiple land and water features for the Minnehaha Creek Watershed and 

Hennepin Park District, as shown in Figure 4-7. This Web-based capability uses ArcView Internet 

Map Server (IMS) to distribute GIS data. Users can zoom in and out of maps and perform queries 

to gather information about different map elements. The IMS allows users to turn off different 

kinds of map layers such as roads and water bodies. The IMS screen has three sections: 

• A toolbar for performing map operations 

• An interactive legend that turns off different layers 

• A frame that shows the map itself 

CASE STUDIES 4-21
Figure 4-7. A GIS map from the Lake Access Web site. Source: Lake Access, 2002. 

The DVToolkit and the GIS mapping function, all freely and easily accessible via the Lake Access 

Web site, are valuable data visualization tools that offer users the power to display different aspects 

of water quality that interest them. Using the color-coded and graphical displays created by these 

tools can help local officials and water users make decisions based on actual, near-real-time water 

quality data. 

4.4.2.6 OUTREACH 

To effectively market the Lake Access tools to local officials and the general public, Lake Access 

project coordinators worked with naturalists, teachers, museum officials, and others. After discussing target audiences, key messages, and the types of outreach materials they thought should 

be developed, the project team created a variety of materials, including a Web site, a printed 

brochure, and a survey. Kiosks were developed to reach those without Internet access. 

Brochure and Survey. The Lake Access project released a “plain English” brochure describing the 

components of the project. The brochure, a two-page, four-color publication entitled Seeing Below 

the Surface, targets both the general public and those decision-makers interested in water quality 

data, explains how the data are collected through RUSS units, and provides easy-to-follow information on the data visualization tools available through the project’s Web site. 

The Lake Access project also conducted a survey to ascertain the public’s general knowledge 

of lakes and water quality and land-use issues in the Hennepin County area in Minnesota. 

Administered to 450 randomly selected addresses, the survey included a cover page explaining the 

Lake Access project, a postcard that residents could return if they wanted to participate in a focus 

group, and a questionnaire covering lake use, level of concern about lake water quality, and preferred ways of receiving Lake Access project information. Forty percent of the residents responded 

to the survey, and the results revealed that residents were generally somewhat concerned about or 

interested in the lake and water quality. 

Kiosks. The Lake Minnetonka Regional Parks Visitor’s Center, the Eastman Nature Center, the 

Science Museum of Minnesota, and the Great Lakes Aquarium in Duluth set up kiosks for users 

without Internet access. The kiosks feature the same information as that found on the Lake Access 

4-22 Chapter 4
Web site. Using a touch-screen computer at the kiosks, users can access the same time-relevant data 

from the RUSS units. 

Presentations. The Lake Access team also gives presentations to local officials. After using simple 

visual tools, such as pie charts, to explain water quality data, the team encourages officials and 

other interested parties to visit the Web site to explore its DVToolkit and GIS mapping features. 

4.4.3 KEY ACCOMPLISHMENTS 

Local officials typically rely on scientists and engineers for water quality advice because of the technical nature of the subject. By making highly technical data accessible and comprehensible to a lay 

audience, Lake Access more directly involved the public in decision-making about water quality 

issues. 

4.3.3.1 LAKE MINNETONKA 

The Lake Access project has not only helped educate people about local water quality issues, but 

also saved tax dollars. For example, a consulting group had recommended an $8 million project to 

eliminate “external loading” (phosphates that enter a water body) of phosphates into Lake 

Minnetonka. After data were analyzed, however, it was apparent that external loading was not as 

critical as “internal loading” (existing phosphates that have settled to the bottom of the lake and 

dissolve in the water). The $8 million project would not have addressed this problem. The Lake 

Access team used the project’s data visualization tools to persuade local decision-makers to consider 

these facts, and the $8 million project did not proceed. 

4.3.3.2 PHOSPHORUS RUNOFF 

The Lake Access team also demonstrated the negative impacts on water quality from the use of 

phosphorus-containing lawn fertilizers. High phosphorus concentrations in a lake promote rapid 

growth of algae and other plant life, adversely affecting water quality. Public education through the 

Lake Access data visualization and interpretation tools has prompted legislative activity to restrict 

the use of phosphorus fertilizers. 

4.4.4 LESSONS LEARNED 

• The Lake Access team learned that traditional graphing techniques, such as simple pie charts 

and bar graphs, are quite effective in communicating environmental information to the public. Lake Access uses a variety of more innovative data visualization tools in its outreach to 

environmental managers and elected officials, but it sometimes relies on the more traditional 

tools for its public outreach efforts. 

• The Lake Access team’s partnership with a local university (the University of Minnesota) 

greatly facilitated the design and maintenance of the Lake Access Web site. Major research 

universities often have large, highly trained information technology departments; by partnering with the University, the Lake Access project gained access to knowledgeable Web designers 

at a reasonable cost. 

• The Lake Access project planners found that the continual development of new data presentation and interpretation features is a major part of the labor involved in maintaining the Lake 

Access Web site. The Web site staff spend about 50 percent of their time maintaining existing 

data presentation components and about 50 percent developing and bringing new data presentation tools online. 

Lake Access is starting a new project to analyze phosphorus runoff. The tool will use a GIS 

mapping function for evaluating a Minnesota watershed that drains into Lake Medicine. This 

new model will be based on a pre-existing one called the Source Loading and Management Model. 

The new model will be available on the Lake Access Web site once it is complete. 

CASE STUDIES 4-23 
Use data visualization as much as possible, and minimize the use of lengthy text. 

When using text, use language that is appropriate for your audience. 

It is often possible to use data visualization tools such as icons, maps, graphs, or 

other visual tools in place of language to convey risk information. These visual 

tools are useful because they tend to transcend cultural boundaries and differin

educational levels more easily than language does. Thus, your message may be 

understood by more people through data visualization than through text. For 

example, the icon on the left may be universally understood without words. 

Some information, however, may be too complex to present without any language. When develo

ing written communications, be sure to use a level of language that accurately represents your pa

ticular audience. For example, you may want a brochure written at an elementary school reading 

level, with simple explanations of technical information, when addressing the general public or a 

more targeted audience that may have little or no knowledge about the subject matter. For a mo

specialized audience with some knowledge and education about a particular subject, you may wa

to develop text written at a junior high school or higher reading level, with more detailed techni

information. If a brochure is for both the general public and a more educated audience, the mor

advanced text might be placed is a separate section or in a sidebar. 

Use universal colors and images whenever possible. 

Some colors schemes and images are almost universally recognized, such as red f

“stop,” green for “go,” and yellow for “caution.” Also, the icon of a circle with a 

line through it is now well known to mean “don’t do this”; superimposing this 

symbol on a picture of a swimmer is a quick and easy way to communicate “do

swim here” to a wide audience with varying degrees of education whose membe

may speak different languages. 

Using tools such as standardized icons and color-coding can increase the usefulness of your risk 

communication materials. 

GUIDELINES 
gyg

It is equally important to let people know what actions they can take to avoid such risks, such 

avoiding time in the sun on certain days, refraining from swimming in a particular beach area 

day or two, or obtaining state advice about whether they should get their backyard soil cleaned 

These risk avoidance actions should ideally be communicated simultaneously with the risk exp

sure information. 

Determine the best communication style: “Telling” or “User-Controlled” 

Often one of the first steps in a risk communication/outreach program is determining who you

audience is (deciding on your “target audience”), analyzing their information needs, and choos

the best communication style to fit those needs. For example, will your risk communication st

gy involve primarily “telling” a large segment of the general public some relatively simple infor

tion, or will it involve giving a more specialized, knowledgeable audience some control in selec

the different types of information they are seeking? The latter might involve setting up a relativ

more complicated environmental database that allows some “user control.” Some projects use a 

combination of these two styles, first providing general information in a “telling” style, then pr

senting more detailed information (or, on a Web site, links to such information). 

THE “TELLING” STYLE OF RISK COMMUNICATIO

When your strategy involves providing (“telling”) relatively simple risk information to people w

little prior knowledge about a subject, some of the guidelines described above for risk commun

tion are particularly important, such as using visual tools and relatively simple language. For ex

ple, the designers of the Southeastern Wisconsin Beach Health Web site, which provides inform

tion about beach water quality conditions and closures, established a system for presenting rela

ly simple data about beach water quality. All visitors to this Web site initially receive essentially 

same type of information (e.g., beach quality on specific days at particular beaches) presented i

essentially the same way. (For users with a more detailed interest in water quality trends or spe

test results, the Web site also provides a “user-controlled” section; after specifying particular da

sets and time periods, more advanced users can obtain detailed laboratory results presented in 

ular form.) Even when using the “telling” mode of communication, it may be useful to provide 

option to display the Web site in a language other than English. 

Risk communicators (including Web site designers) seeking to “tell” information to the public 

should avoid overestimating the amount of effort that their audience is willing to expend in pu

suit of this information. Ideally, for a Web site, the user should not be required to do more tha

type in a single, memorable URL and then make one or two obvious clicks of the mouse in or

to view the risk information. 

5-2 Chapter 
these predictions directly from the SunWise Web site or through other media, such as television o

newspaper weather reports. 

http://www.epa.gov/sunwise/uvindex.html 

http://www.epa.gov/sunwise/uvindexcontour.html 

GUIDELINES 
http://infotrek.er.usgs.gov/pls/beachhealth 

THE “USER-CONTROLLED” STYLE OF RISK

COMMUNICATION 

Some projects serve a smaller audience (e.g., a subset of the public, local health officials, etc.) t

is likely to have specific and detailed interests in particular aspects of a project’s environmental 

data. The risk communication/outreach strategies for these projects may be most useful if they 

users more control over what information they obtain and how their data are presented. For ex

ple, the Lake Access project presents information about how water quality in certain lakes varie

with depth and over time. Someone with an interest in such specialized data may have a fair 

amount of education on the topic and be willing to expend some energy in pursuing the inform

tion. It is also reasonable to assume that the precise nature of such an informed user’s interest 

would be difficult for a risk communicator to anticipate. Therefore, it would make sense to pro

vide greater complexity and flexibility in using data visualization and interpretation tools than 

the “telling” risk communication style described above. 

Examples of EMPACT projects that follow the “user-controlled” style of presentation include: 

Lake Access, Boulder Area Sustainability Network (BASIN), Des Moines Waterworks, and the 

Monitoring Your Sound (MYSound) project for Long Island Sound, as discussed below. 

5-4 Chapter 
Des Moines Water Works. The Des Moines Water Works has established a Web site to provide 

information about the water quality of its drinking water sources. It provides users with custom 

water quality reports (including some graphs) in response to input queries. The user’s input query 

provides information about the particular water source, laboratory test, and time period of interes

to the user. 

GUIDELINES 
http://www.mysound.uconn.edu 

CONCLUSION 

The projects discussed in this handbook illustrate the wide range of data visualization and data 

interpretation tools and techniques available for environmental risk communication, including 

time-relevant environmental information. We hope that you have found these tools interesting 

useful for adaptation to your own risk communication efforts. We also hope that this handboo

stimulates further research and encourages development of additional tools to communicate en

ronmental risk. 

Table 5-1 lists the addresses of the project Web sites discussed in this handbook; visit these site

you wish to explore the projects’ risk communication messages further. The Reference list inclu

additional resources. Also, an overview of environmental risk communication can be found in 

EPA’s publication Considerations in Risk Communication: A Digest of Critical Information (order 

EPA/625/R-02/004). Ordering information for other titles in this series can be found in the or

booklet EPA/625/N-02/001 or at the EPA Web site: http://www.epa.gov/ttbnrmrl. 

Table 5-1. Websites of Projects Highlighted in this

Handbook 

EPA AIRNow http://www.epa.gov/airnow 

Web Site Name URL 

Boulder Area Sustainability Information Network http://bcn.boulder.co.us/basin 

Charles River Basin Flagging Program 2002 http://www.crwa.org/wq/daily/2002/daily.html 

Des Moines Water Works EMPACT Project http://www.dmww.com/empact.asp 

Smog City http://www.e-tulsa.net 

Lake Access http://www.lakeaccess.org 

Miami Valley River Index http://www.riverindex.org 

MYSound http://www.mysound.uconn.edu 

Southeastern Wisconsin Beach Health http://infotrek.er.usgs.gov/pls/beachhealth 

Spare the Air http://www.sparetheair.com 

EPA SunWise School Program http://www.epa.gov/sunwise 

Texas Natural Resource Conservation Commission: 

Air Monitoring http://www.tnrcc.state.tx.us/air/monops/index.htm

5-6 Chapter 
Lake Access. 2002. <http://www.lakeaccess.org> 

National Weather Service. 2002. National Oceanic and Atmospheric Administration.


<http://www.nws.noaa.gov>


River Index Project. 2002. Miami Valley River Index. <http://www.riverindex.org>


Sacramento Metropolitan Air Quality Management District. 2002. Ozone movie archive.


<http://www.sparetheairnow.com/moviearchive.html> 

Stone, S. 2000. Structure of the Air Quality Index (AQI). In: Air Quality Index and Emission 

Inventory for Delhi: Abstracts. June 6-8, New Delhi. Centre for Science and Environment, India 

Habitat Centre, New Delhi. 

Texas Natural Resource Conservation Commission. 2002. Animated ozone concentrations. 

<http://www.tnrcc.state.tx.us/cgi-bin/monops/ozone_animation> 

Tulsa Air and Water Quality Information System. 2002. <http://www.e-tulsa.net/smogcity/smog1.html

University of Connecticut. 2002. MYSound. <http://www.mysound.uconn.edu/index.html> 

U.S. EPA. 1998. Report of eight focus groups on the Ozone Map, the Pollutant Standards SubIndex for Ozone, and the Ozone Health Effects Booklet. Report prepared by Eastern Research 

Group, Inc. Washington, DC. 

U.S. EPA. 1999a. Air quality guide for ozone. EPA/456/F-99/002. Washington, DC. 

U.S. EPA. 1999b. Guideline for developing an ozone forecasting program. EPA/454/R-99/009. 

Research Triangle Park, NC. 

U.S. EPA. 1999c. Guideline for reporting of daily air quality—Air Quality Index (AQI). 

EPA/454/R-99/010. Research Triangle Park, NC. 

U.S. EPA. 1999d. Ozone and your health. EPA/452/F-99/003. Washington, DC. 

U.S. EPA. 2000. Delivering timely water quality information to your community: the Lake 

Access–Minneapolis project. EPA/625/R-00/013. Washington, DC. 

U.S. EPA. 2002a. SunWise school program. <http://www.epa.gov/sunwise> 

U.S. EPA. 2002b. Office of Environmental Information. <http://www.epa.gov/oei> 

U.S. EPA. 2002c. AIRNow. <http://www.epa.gov/airnow> 

Weather Channel. 2002. Air quality forecast. <http://www.weather.com/activities/health/airquality/> 

REFERENCES