EPA-23 0-12-85-026
September 1985
METHODS DEVELOPMENT FOR ENVIRONMENTAL
CONTROL BENEFITS ASSESSMENT
Volume VIII
THE BENEFITS OF PRESERVING VISIBILITY IN THE
NATIONAL PARKLANDS OF THE SOUTHWEST
by
William D. Schulze and David S. Brookshire
University of Wyoming
Laramie, Wyoming 82 0 71
Eric G. Walther
Visibility Research Center of the John Muir Institute
University of Nevada-Las Vegas
Las Vegas, Nevada 89154
Karen Kelley
National Park Service
Washington, D.C. 20240
Mark A. Thayer
San Diego State University
San Diego, California 92182
Regan L. Whitworth
Billings, Montana
Shaul Ben-David
University of New Mexico
Albuquerque, New Mexico
William Maim and John Molenar
Environmental Monitoring Systems Laboratory
U s . Environmental Protection Agency
Las Vegas, Nevada 8 9114
USEPA Grant # R805059-01-0
Project Officer
Dr. Alan Carlin
Office of Policy Analysis
Office of Policy, Planning and Evaluation
U*S. Environmental Protection Agency
Washington, D.C. 20460
OFFICE OF POLICY ANALYSIS
OFFICE OF POLICY, PLANNING AND EVALUATION
U.S. ENVIRONMENTAL PROTECTION AGENCY
WASHINGTON, D.C. 2 04 60
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Volume 6, The Value of Air Pollution Damages to Agricultural Activities in
Southern California, EPA-230-12-85-024.
This volume contains three papers that address the economic implications
of air pollution-induced output, input pricing, cropping, and location pat-
tern adjustments for Southern California agriculture. The first paper esti-
mates the economic losses to fourteen highly valued vegetable and field crops
due to pollution. Thg second estimates earnings losses to field workers ex-
posed to oxidants. The last uses an econometric model to measure the reduction
of economic surpluses in Southern California due to oxidants.
Volume 7, Methods Development for Assessing Acid Deposition Control Benefits,
EPA-230-12-85-025.
This volume suggests types of natural science research that would be most
useful to the economist faced with the task of assessing the economic benefits
of controlling acid precipitation. Part of the report is devoted to develop-
ment of a resource allocation process framework for explaining the behavior of
ecosystems that can be integrated into a benefit/cost analysis, addressing
diversity and stability.
Volume 9, Evaluation of Decision Models for Environmental Management, EPA-230-
12-85-027.
This volume discusses how EPA can use decision models to achieve the proper role
of the government in a market economy. The report recommends three models useful
for environmental management with a focus on those that allow for a consideration
of all tradeoffs.
Volume 10, Executive Sumtiary, EPA-230-12-85-028.
This volume summarizes the methodological and empirical findings of the series.
The concensus of the empirical reports is the benefits of air pollution control ap-
pear to be sufficient to warrant current ambient air quality standards. The report
indicates the greatest proportion of benefits fran control resides, not in health
benefits, but in aesthetic improvements, maintenance of the ecosystem for recreation,
and the reduction of damages to artifacts and materials.
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DISCLAIMER
This report-has been reviewed by the Office of Policy Analysis, U.S.
Environmental Protection Agency, and approved for publication. Mention in
the text of trade names or commercial products does not constitute endorse-
ment or recommendation for use.
ii
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ABSTRACT
The nation needs to know how much visibility is worth in order to evaluate
the benefits of air pollution control for the purpose of visibility protection.
This study was designed to measure the economic value of preserving visibility
in the National Parklands of the Southwest. During the summer of 1980, over
six hundred people in Denver, Los Angeles, Albuquerque and Chicago were shown
sets of photographs depicting five levels of regional visibility (haze) in
Mesa Verde, Zion and Grand Canyon National Parks. Although our calculations
suggest that projected emissions with existing and currently planned S02 con-
trols would not produce a perceived decline in visibility, complete decontrol
of S02 emissions by projected power plants in the region in 1990 would result
in a decrease in typical summer visibility from that which was represented in
the photographs as "average" visibility to that which was represented as "below
average" visibility. On the basis of this, the survey participants were asked
how much they would be willing' to pay in higher electric utility bills to pre-
serve the current average condition — middle pic ture--ra ther than allow visi-
bility to deteriorate, on the average, to the next worse condition as repre-
sented in the photographs (an estimate of total preservation value). They
were also asked about their willingness to pay in the form of higher monthly
electric power bills to prevent a plume from being seen in a pristine area.
To represent plume blight, two photographs were taken from Grand Canyon
National Park, one with a visible plume. The surveying had a very high response
rate (few refusals). Individual household bids ranged from an average of $3-72
per month in Denver to $9.00 per month in Chicago for preserving visibility at
the Grand Canyon. These average bids were increased by $2.89 to $7.10 per
month per household in the four cities if visibility preservation was to be
ext.ended to the Grand Canyon Region as a whole as represented by the photographs
taken from Mesa Verde and Zion. Prevention of a visible plume at the Grand
Canyon was worth on the average between $2.84 and $A.32 per month for the four
cities surveyed. Extrapolating these bids to the nation implies that preserving
visibility in the Grand Canyon Region is worth almost 6 billion dollars per
year. This is the base figure from which the benefits of power plant S02 con-
trols, projected to be in place in the region in 1990, are determined.
Adjusting this number for 1990 population levels and using a 10 percent dis-
count rate over a thirty year power plant life gives an annualized value of
7.6 billion dollars as the benefits of power plant S02control. The corre-
sponding control costs are estimated to be approximately three billion dollars
annually. Therefore, the existing and proposed control level in the Region is
not without economic justification. Additionally, prevention of a visible
plume at the Grand Canyon is worth almost two billion dollars to the nation.
These results suggest that preservation values derived from knowledge that a
unique natural wonder remains preserved may be very large for the Grand Canyon
Reg ion. Finally, the methodology used must be considered experimental since
this is the first study, to our knowledge, to include an estimate of preserva-
tion value for a unique national treasure.
iii
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CONTENTS
Page
Abstract iii
List of Tables i i i
List of Figures x'
i
Acknowledgements x i i
Executive Summary 1
Chapter 1 - Introduction 8
A. Why This Study? 8
B. The Value of Good Visibility to Society 8
c. History of Federal Visibility Protection 9
The 1977 Clean Air Act Amendments 9
1980 Visibility Regulations 10
D. Issues ^
E. Organization of the Report
Chapter 2 - Representing Visibility with Photographs 13
A. Photographs Used in the Survey 13
B. Data Base
Chapter 3 - Regional Emissions and Visibility 20
A. Introduction 20
B. Relating Visibility to Emissions 20
c. EmissionScenariOs 23
Scenario 0 ... 23
v
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CONTENTS, continued D
Page
Scenario 1 23
Scenario 2 26
D. Conclusions 29
Chapter 4 - Perception of Visibility 32
A. Introduction 32
B. Summary of Perception Studies 32
c. Study Results 34
D. Conclusion 44
Chapter 5 - Measuring the Economic Value of Visibility 45
A. Introduction 45
B. The Theoretical Basis - The Economics of
Preservation ^6
Chapter 6 - Survey Design 51
A. Introduction 51
B. Survey Instrument Structure 51
c. User Valuation Questions 55
D. preservation Value Analysis &0
C h a p t e-Snrvey7 Results 62
A. Introduction 62
B. Socio-economic and Demographic Characteristics
of the Sample 62
c. Value in Use to Visitors 65
D. Preservation Value 69
Chapter 8 - Aggregate Benefits of Preserving Visibility 77
A. Introduction 77
B. Estimating the Benefit Function for the Southwest ... 77
vi
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CONTENTS, continued page
c. Estimating the Benefit Function for the Nation 79
D. Summary 83
Appendix A - Theory of Visibility Applicable to this study 85
Appendix B - Valuing"Public Goods: A Comparison of Survey and
Hedonic Approaches , . 103
Appendix C - Visibility Questionnaire 122
Bibliography 135
v i i
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LIST OF TABLES
Chapter 2
1. Vista s for Survey 14
2. Photographs" for Plume Question , . . . 18
3. Target Specifications and Slides for Summer 1 980 Study .... 18
Chapter 3
b. Current S02 Emissions in Test Region 2 5
5. Major S02Sources Proposed for Test Region by 1990 27
6. Apparent Green Contrast Change to be Caused in Test
Region by Proposed Sources of S02 28
7. Slides in Regional Scenarios of Uncontrolled S02Emissions ... 30
Chapter 4
8. Correlation Coefficients between IPV and Cq , 36
9. Statistical Analysis of On-site and Slide Ratings 41
Chapter 6
10. Description of the Areas Sampled for the National Park
Survey - LosAngeles County 56
11. Description of the Areas Sampled for the National Park
Survey - Albuquerque Metropolitan Area 57
12. Description of the Areas Sampled for the National Park
Survey - Denver Metropolitan Area 58
Chapter 7
13a. Socioeconomic Characteristics of Preservation Value
Respondents by city (mean and standard deviation) . . . .". 63
13b. Socioeconomic Characteristics of User Value Respondents
by city (mean and standard deviation) 63
14a. Zero Bids by User Value Respondents for Specified
Visibility Improvements, by city (# of zero bids) 67
14b. Zero Bids by Reason Among User Value Respondents 67
15a. Southwest' National Park Use Patterns (by city) for User
Value Respondents (# of days at Parks during previous
10 Years, mean and standard deviation) 67
15b. Use Patterns Among User Value Respondents by Income
Classifications (mean days in previous 10 years) 67
v i i i
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Chapter 7 (continued)
16. Southwest National Park Use Patterns (by city) for
Preservation Value Respondents (# of days at Park during
Previous 10 years; mean and standard deviation) 71
17. Preservation Value Bids by city, mean and standard
deviation($) 71
Chapter 8
18. Benefit Functions Estimated from Albuquerque, Denver and
LosAngeles Data 78
19. Annual Aggregate Benefits for the Southwest Region
($ Millions) 79
20. Benefit Functions Estimated from Albuquerque, Denver, Los
Angeles and Chicago Data 79
21. Annual Aggregate National Benefits from Preserving Visibi-
lity in the Grand Canyon National Park ($ Millions) .... 81
22. Present Value of Future Benefits Assuming 30 Year Life Span
for Power Generating Plants 82
Appendix B
B1 . Estimated Hedonic Rent Gradient Equations 116
B2. Tests of Hypotheses 117
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LIST OF FIGURES
Chapter 2
1. Photographs of Grand Canyon Visibility 15
2. Photographs 'of"'Southwestern National Parks Regional
Visibility . . 16
3. Photographs of Grand Canyon Plume Analysis 17
Chapter 3
4. Test Region 24
Chapter 4
5. Index to Perceived Visual Air Quality as a Function of
Apparent Target Contrast for the Clear Sky Conditions .... 35
6. Index to Perceived Visual Air Quality as a Function of
Apparent Target Contrast for Cumulus Cloud Conditions .... 37
7. Index to Perceived Visual Air Quality as a Function of
Apparent Target Contrast for Overcast Cloud Conditions ... 37
8. Contrast Change Resulting from an Increase in Fine
Particulate - 38
9. Index of Perceived Air Quality Versus Change in Overall
Vista Color 38
10. Mean Rating of a Series of 6 Slides Taken at the La Sal
Mountains 40
11. Average Perceived Visual Air Quality Ratings of 13 Different
Three Dimensional Scenes Plotted Against Corresponding
Ratings of Slides Representing the Same Scenes 42
Chapter 6
12. Regional Map '.52
13. Questionnaire Structure 53
Chapter 7
I b. Grand Canyon Visitation 64
15. Mean Bid for Specified Visibility Conditions at the Grand
Canyon 66
16. Mean Regional and Plume Avoidance Bid by User Value
Respondents by City 68
17. Grand Canyon Visitation Experience and Expectations of
Preservation Value Respondents 70
18. Mean Grand Canyon Bids of Preservation Value Respondents
by City and Past and Future Visitation 73
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19. Mean Total Regional Bids of Preservation Value Respondents
by City and Past and Future Visitation 74
20. Mean Plume Avoidance Bids of Existence Value Respondents
by City and Past and Future Visitation 75
Appendix A
AI. Spectral Radiance 8 6
A2 . Scattering 88
A3. Absorption.'"." 8 a
A4. Schematic Representation of Vision through the Atmosphere . . . . 89
A5. The Dependence of Target Radiance on Distance 90
A6. Absorption/Extinction Measurements Versus Site Location 93
A7. Rayleigh Scattering Dependence on Observation Angle 95
A8. Observation Angle Scattering Dependence for Particles 96
A9. Scattering Efficiency Factor 9 7
A10. Range of variability in Humidogram data averaged by site 99
All. Absorptivity of N02 as a function of Wavelength of
Incident Light 100
A12. Characteristic Absorption Wavelength Dependence
Measurements 102
Appendix B
61. With identical housing attributes 113
62. With differing housing attributes 114
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ACKNOWLEDGEMENTS
We thank Phil Wondra and Dave Shaver of the National Park Service for
their helpful guidance during the design of the survey methodology. We thank
the Park Service for permission to use the photographs taken from the photo-
graphic monitoring program at several parks. Additionally, George Tolley and
John Hoehn of the University of Chicago and Glen Blomquist of the University
of Kentucky collected data in Chicago for this study and contributed greatly
to the research preparation. Ralph d'Arge and Thomas Crocker also provided
helpful suggestions throughout the research effort. Our thanks also go to
LeAnn Lively and Ema Bixler for editing and manuscript preparation. Research
Assistants at the University of Wyoming who worked on the project include
Morteza Rahmatian, John Hovis, Laura Bibo, William Weir ick, Col leen Kalsbeck,
Lou Murdoch, Jim Murdoch, Kim Case, Cale Case, and Patricia Smith.
x i i
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EXECUTIVE SUMMARY
THE BENEFITS OF PRESERVING VISIBILITY IN THE
NATIONAL PARKLANDS OF THE SOUTHWEST
The nation needs to know how much visibility is worth in order to eval-
uate the benefits of air pollution control for the purpose of visibility pro-
tection. This study was designed to measure the economic value of preserving
visibility in the National Parklands of the Southwest.
Historically Americans have placed a high value on good visibility,
that is, the ability to see distant objects clearly. This yearning for and
appreciation of atmospheric visual clarity is evidenced in the country's early
literature and art, including the Journals of Lewis and Clark as well as the
masterpieces of the great American landscape artists of the 19th century.
Today that love of visibility is demonstrated not only by the millions who
flock each year to our western parks, but also in the high prices brought by
those artists' work of a century ago and by the interest in Ansel Adams'
simple, yet dramatically clear black and white photographs of Yosemite and
other wonders of the U.S. National Park Service.
Over the past 100 years, Congress has acted to preserve many of our
nation's natural wonders. [t did so by creating and continually expanding the
National Parks, National Wilderness Areas, National Monuments, National
Recreation Areas, and Wild and Scenic Rivers.
Since the 1950s there seems to have been an increasing concern that
this beauty is threatened by industrial development and population growth.
Pollution from coal-fired power plants became a special concern with the advent
in 1963 of the first unit of the Four Corners Power Plant near Farmington, New
Mexico. It produced a plume that could be seen clearly for many miles,
reducing the clarity of the visual experience in areas of northwestern New
Mexico, southeastern Utah, southwestern Colorado and northeastern Arizona.
By the late 1960s and the early 70s, smog began to appear in Yosemite
Valley on warm summer days. Battles erupted over proposed coal-fired power
plants on the Kaiparowits Plateau and near Capitol Reef National Park, both
in southern Utah, because of their possible effects on visibility. The
increased publicity and concern resulted in magazine and newspaper articles
decrying the loss of visual clarity, particularly in the western United States,
and precipitated political pressures in Congress for legislative steps to pro-
tect visibility. Those pressures culminated in the August 1 977 adoption by
Congress of the nation's first specific visibility protection requirements for
national parks and national wilderness areas as amendments to the Clean Air
Act of 1 970. One of the large issues raised by these developments is whether
the value of visibility protection outweighs the cost, including air pollution
1
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control equipment and the regulatory requirements. The study reported on here
is designed to improve our ability to measure the benefits of visibility and
to provide some actual estimates of the value of that visibility in several
major national parks and for the region in which they are located. The region
and the parks located in it are shown on the map below. We refer to this area
as the Grand Canyon Region.
IS
0
REGIONAL MAP
REGIONAL INDUSTRIAL FACILITIES
Exampia list of Industrie Facilities
1. Navaio Power Plant, Pagt, AZ
2. San Juan Plant: Fruitland.NM
3. Four Corner*: Farmington, NM
4: Copper smelters, throughout Arizona
Pfanntd
5. Intermountain Power Plant (Utah)
6. Garfield Power Plant (Utah!
7. Warner Power Plant (Utah)
Pomts of fntantst
(7,178 ft.) Shiprock.NM
(7,178 ft.) Shiprock. NM -35 miles
from Mesa Verde
[8,029 ft.) Trumbull Mountain, AZ . 50
miles from Zion and 1 miie
from Grand Canyon
a
Visibility is the ability to clearly see both color and detail over long
distances. Human perception of visual air quality is associated with the ap-
parent contrast of distant visual targets with respect to their surroundings.
As contrast is reduced, a scene "washes out" both in color and in the
ability to see distant detail.
What then is the nature of the preservation value of visibility? That
value has at least-two possible components.
First, a scenic resource such as the Grand Canyon attracts millions of
recreators each year. The quality of the experience of these recreators
depends in great part on air quality, because scenic vistas are an integral
part of the Grand Canyon "experience." Thus, air quality at the Grand Canyon
is valuable to recreators. We might call this economic value user value,
or. the willingness to pay by users for air quality at the Grand Canyon. Thus ;
recreators in the National Parklands of the Southwest should be willing to pay
some amount to preserve air qual ity for each day of their own use if their
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recreation experience is improved by good air quality. One hypothetical
market for collecting user value is an increase in entrance fees to parks to
be used to finance preservation of air quality, i.e., purchase ofair pollu-
tion control equipment. Survey questionnaires can be designed to estimate
user value based on such a hypothetical market.
The second component of preservation value is termed existence value.
Individuals and households which might never visit the Grand Canyon can still
value visibility the,re . .s imply because they wish to preserve a national treasure.
Visitors also may wish to know that the Grand Canyon retains relatively pris-
tine air quality even on days when they are not visiting the park. Concern over
preserving the Grand Canyon may be just as intense in New York or Chicago as it
is in nearby states and communities.
Thus, preservation value has two additive components, user value and
existence value. However, it is difficult to construct even a hypothetical
market to capture existence value alone. Rather one could imagine a lump sum
fee added, for example, to electric power bills to preserve air quality in
the Grand Canyon and the surrounding parklands. Such a hypothetical fee would
capture total preservation value, the sum of existence plus user value, if
used as the basis of a survey questionnaire. In fact, the survey conducted
for this study asked approximately one-third of the respondents a pure user
value question (how much would they be willing to pay in higher entrance fees
per day for visibility at the Grand Canyon or other parks). The other two-
thirds of the respondents were asked how much they would be willing to pay at
most as a higher monthly electric power bill to preserve visibility first at
the Grand Canyon and second throughout the region as represented by photographs
of vistas at the Grand Canyon, Mesa Verde and-Zion National Parks (total pre-
servation value questions). Clearly, if total preservation value is much
larger than total user value, then existence value must be large.
During the summer of 1980, over six hundred people in Denver, Los Angeles,
Albuquerque and Chicago were shown sets of photographs depicting both clear
visibility conditions and regional haze conditions. Each set consisted of
5 photographs ranging from poor to excellent visibility. The middle picture in
each case approximated average visibility during the summer (the season of peak
visitation). The vistas were 3 different views from the Grand Canyon, 1 view
from Mesa Verde and 1 view from Zion. The 8 by 10 inch textured prints were
placed on display boards, each vista a separate row, and each row arranged with
5 photographs from left to right in ascending order of visual air quality (i.e.,
photograph A = "poor" visibility and photograph E = "excellent" visibility).
The relationship between the five levels of visibility shown in the
photographs to regional emissions can be summarized as follows: if (1) all
controls on S02for existing power plants in the region were removed; (2)
proposed power plants (through 1990) in the region were to emit SQ at the
maximum uncontrolled rate; (3) existing smelter emissions were hela constant;
and (4) particulate emissions remain at current levels, visibility would then
decline from current average conditions (middle photographs) by one step to
the level presented in the photographs just to the left of center. Thus ,
where the photographs can be described as representing "poor," "below average,"
"average," "above average" and "excellent" visibility, complete decontrol of
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Si\ emissions by projected power plants in the region in 1990 would result in
a decrease in typical summer visibility from that which is represented in the
photographs as "average" visibility to that which is represented as "below
average" visibility. The calculations which form the basis of the relation-
ship between the levels of visibility which were shown in the photographs and
regional emissions are presented in Chapter 3.
The survey participants were asked either (1) how much they would be
willing to pay for visibility as shown in the five sets of photographs from
worst to best on the day of a visit to the Grand Canyon (an estimate of user
value) or (2) how much they would be willing to pay in higher electric utility
bills to preserve the current average condition — middle pic ture--r a ther than
allow visibility to deteriorate, on the average, to the next worse condition
as represented in the photographs of the Grand Canyon or of the region (an
estimate of total preservation value). They were also asked about their
willingness to pay in the form of higher monthly electric power bills to pre-
vent a plume from being seen in a pristine area. To represent plume blight,
two photographs were taken from Grand Canyon National Park. Both photographs
are essentially identical except one has a plume, a narrow gray band, crossing
the entire vista in the sky. The source was not industrial or municipal pol-
lution but a controlled burn in the area around the Grand Canyon. However,
the effect was comparable to what a large uncontrolled industrial source might
produce.
The bidding game reveals the household's willingness to pay for pre-
serving visibility in specific locations as represented in the photographs.
For the interviewees asked the preservation value questions in the survey,
the bids include both existence value and user value. Therefore, we concen-
trate on the preservation value section of the survey here, since user values
are included in the preservation estimates.
The surveying had few refusals, partly because of the nature of the
interviews. Typically, interviews were conducted in the late afternoon or
early evening hours in residential neighborhoods. Due to the large size of
the display boards, most interviews were conducted on the front lawn
of the respondent's home. Often, both husband and wife partici-
pated jointly in answering the questions. This was viewed as appropriate
since the principal question was "how much would you be willing to pay in
higher monthly electric utility bills to preserve visibility at the Grand
Canyon or in the entire Grand Canyon region?" Household members would
often engage in extensive discussion before giving a dollar amount. In-
dividual bids ranged from an average of $3.72 per month in Denver to $9.00
per month in Chicago for preserving visibility at the Grand Canyon.
These average bids were increased from $2.89 to $7.10 per month per household
in the four cities if visibility preservation was to be extended to the Grand
Canyon region as a whole. Prevention of a visible plume in the Grand Canyon
was worth on the average between $2.84 and $4.32 per month for the four cities
surveyed.
The. validity of these survey results depends on the perception by indi-
viduals of visibility conditions as represented by photographs. A linear
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relationship has been shown to exist between perceived visibility as quantified
by individuals in a numerical one to ten ranking of visual air quality as
represented in an actual view and with the scientific measure of the apparent
contrast in the vista by a multiwavelength teleradiometer. This close linear
relationship between perception of an actual vista and the apparent contrast
of the vista also extends to perception of visibility conditions represented
by slides or 8" x 10" color photographs as is shown in the research presented
in Chapter 4.
The benefit estimates derived from the interview results can be extra-
polated from the sample population to the country as a whole by applying
statistical extrapolation techniques to the results of the survey. The bids
offered by interviewees to preserve visibility are statistically related to
income as well as other demographic characteristics. Using the estimated
linear relationship of bids to population characteristics, it is possible
to estimate the value of benefits to residents both for the entire Southwest
region and for the entire nation. This is done by substituting the average
value for these characteristics for each state into the relationship and
calculating the average value of the bid of a person in that state. This
value is then multiplied by the number of households in the state to get
a total bid or benefit.
When the analysis is performed for the southwestern U.S. (for residents
of California, Colorado, Arizona, Utah, Nevada, and New Mexico), the following
values are obtained.
Yearly Benefits from: Total ($mi 11 ion)
Preserving Visibility at the
Grand Canyon 470
Preserving Visibility at the
Grand Canyon Region 889
Preventing Plume Blight at the
Grand Canyon 373
To estimate the aggregate national benefits for preserving visibility,
a similar analysis is done for the entire U.S. and the following values are
obtained.
Yearly Benefits from: Total ($mil lion)
Preserving Visibility at the
Grand Canyon 3,370
Preserving Visibility in the
Grand Canyon Region 5,76o
Preventing Plume Blight at the
Grand Canyon 2,040
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The benefits of preserving visibility can be related to emissions by noting
the following. Projected emissions with existing and currently planned levels
of SO2 control would not produce a perceived decline in visibility in 1990
according to our calculations as shown in Chapter 3. However, complete decon-
trol of projected regional power plant emissions of S02 in 1 990 would decrease
visibility by approximately the same amount as the decrease shown in the photo-
graphs which form the basis of the preservation value questions in the survey.
Thus, the regional benefit figure forms the base from which benefits from
power plant S02 controls, projected to be in place in 1 990, are calculated.
¦4 ¦ - ,
Two modifications of the regional benefit figure are necessary. First,
benefits in 1 990 must reflect the expected population levels in that year.
Second, the present value of future benefits, based on a thirty year power
plant life and a 10 percent real discount rate which is consistent with the
Office of Management and Budget guidelines, must be determined. These modifi-
cations yield an annualized value of 7.6 billion dollars as the benefits of
power plant S02 controls.
The corresponding control costs, which include initial capital expendi-
tures, recurring expenditures and the regulatory system cost, are estimated to
be approximately three billion dollars annually. Therefore, estimated national
benefits exceed control costs and the proposed level of S02 control is not
without some economic justification.
Several other observations on the outcomes of the analysis of the inter-
view results are worth mentioning.
First, in the conventional view of the demand for environmental quality,
there is a smooth tradeoff between higher successive levels of environmental
quality and economic benefits, with successive units commanding less incremental
willingness to pay.
The survey respondents in the user portion of the study, however,
placed a much higher value on a small initial diminution in visual clarity
than on comparable subsequent decreases. This would produce a very unusual
upward sloping demand curve for visibility.
Second, again somewhat contrary to expectations, neither past nor pro-
spective visits to the Grand Canyon Region were shown to be important deter-
minants of preservation value. On the average those who had never seen the
Canyon valued it as highly as those who had.
Third, once more unexpected, distance from the region had no significant
relationship to the size of household bids. People in Chicago bid fully as
high as those closer by for preserving visibility at the Grand Canyon.
Fourth, whereas total annual preservation value of the Grand Canyon
Region for the nation approaches six billion dollars, user value is on the
order of tens of millions of dollars. Thus, existence value dominates the
benefits of preserving visibility.
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Because the Grand Canyon is the dominant feature in a region with many
visitor attractions, one must be especially cautious in extending these
findings to other recreational attractions. It seems likely that there are
only a very few natural phenomena in the United States about which Americans
have such strong feelings. Obvious candidates for this short list would be
Old Faithful in Yellowstone National Park, Niagara Falls and perhaps a few
others.
The main conclu^.iari of this study is that the magnitude of the annual
yearly benefits for preserving visibility when aggregated across households is
impressive: nearly one billion dollars in the southwest and about six billion
in the nation.
While these are necessarily rather crude extrapolations, the survey
results reveal that Americans place great value on preservation of air quality
in the Grand Canyon Region and that this valuation is not localized in the
southwest. Again, it is worth noting that pure existence value overwhelms
user value for the National Parks in the region.
The accuracy of these estimates, given the difficulty of quantifying en-
vironmental value in dollar terms, is probably on the order of plus or minus
50 percent. However, the methodology used must still be considered experimental.
The report is organized as follows: Chapter 1 presents the historical,
legal and institutional background for visibility protection. Chapter 2
describes the photographs of vistas in the National Parklands used in surveying
people in four metropolitan areas about the value of preserving visibility in
National Parks. Chapter 3 relates the levels of air quality shown in the
photographs to regional industrial emissions under three alternative scenarios.
Chapter 4 reports on a study of the relationship between perception of air
quality by direct observation as opposed to that presented in slides and photo-
graphs. Chapter 5 describes the economic theoretical basis for the survey
design, which is presented in Chapter 6. Chapter 7 gives the survey results
while Chapter 8 develops an aggregate benefit measure for preserving visibility
in the National Parklands of the southwest. The overall study thus brings
together work from atmospheric physics (Chapters 2 and 3), psychology and
sociology (Chapter 4), and economics (Chapters 5-8) to provide an estimate of
the benefits of preserving visibility in the Grand Canyon Region. Only with
knowledge of (1) how emissions affect visibility, (2) how people perceive
changes in visibility and (3) how people value changes in perceived visibility
in dollar terms can a valid estimate of such benefits be made.
-------
CHAPTER 1
INTRODUCTION
A. Why This Study?
The nation needs to know how much visibility is worth in order to eval-
uate the benefits of air pollution control for the purpose of visibility pro-
tection. This study was designed to measure the economic value of preserving
visibility in the National Parklands of the Southwest.
B. The Value of Good Visibility to Society
Historically Americans have placed a high value on good visibility,
that is, the ability to see distant objects clearly. This yearning and
appreciation of atmospheric visual clarity is evidenced in the country's early
literature and art, including the Journals of Lewis and Clark as well as the
masterpieces of the great American landscape artists of the 19th Century.
Today that love of visibility is demonstrated not only by the millions who
flock each year to our western parks, but also in the high prices brought by
those artists' work of a century ago and by the interest in Ansel Adams'
simple, yet dramatically clear black and white photographs of Yosemite and
other wonders of the U.S. National Park Service.
Over the past 100 years, Congress has acted to preserve many of our
nation's natural wonders. It did so by creating and continually expanding
the National Parks, National Wilderness Areas, National Monuments, National
Recreation Areas, and Wild and Scenic Rivers.
Since the 1950s there seems to have been an increasing concern that this
beauty is threatened by industrial development and population growth. Pollution
from coal-fired power plants became a special concern with the advent in 1963 of
the first unit of the Four Corners Power plant near Farmington, New Mexico. It
produced a plume that could be seen clearly for scores of kilometers, reducing the
the 'clarity of the visual experience in areas of northwestern New Mexico,
southeastern Utah, southwestern Colorado and northeastern Arizona.
By the late 1960s and the early 70s, smog began to appear in Yosemite
Valley on warm summer days. Battles erupted over proposed coal-fired power
plants on the Kaiparowits Plateau and near Capitol Reef National Park and
Zion National Park, both in southern Utah. The increased publicity and concern
resulted in magazine and newspaper articles decrying the loss of visual clarity,
particularly in the western United States, and precipitated political
pressures in Congress for legislative steps to protect visibility. Those
pressures culminated in the August 1 977 adoption by Congress of the nation's
first specific visibility protection requirements for national parks and
national wilderness areas as amendments to the Clean Air Act of 1970.
8
-------
c. History of Federal Visibility Protection
The 1977 Clean Air Act Amendments
The increasing public concern about and Congressional interest in protecting
visibility resulted in specific visibility provisions-being included in the Clean
Air Act Amendment of 1977 (P.L.95~95; August 7, 1 977). The House Commerce Com-
mittee in its report accompanying the amendments to the Clean Air Act, summarized
the Congressional int&nt as follows:
There are certain national lands, including national parks,
national monuments, national recreation areas, national primitive
areas, and national wilderness areas, in which protection of clean
air quality is obviously a critical national concern. In fact the
1916 National Parks Organic Act states the purpose of such lands
"is to conserve the scenery and the natural and historic objects
and the wildlife therein and to provide for the enjoyment of the
same in such a manner and by such means as will leave them unim-
paired for the enjoyment of future generations" (16 U.S.C.I).
Similarly, the 1 964 Wilderness Act provides that wilderness areas:
Shall be administered in such manner as will leave them unimpaired
for future use and enjoyment as wilderness, and so as to provide
for the protection of these areas (and) the preservation of their
wilderness character. (l6 U.S.C. 1131 (c))
In the Committee's view, these unique national lands should
not be despoiled or heavily shrouded in dense industrial pollu-
tion. Indeed, the millions of Americans who travel thousands of
miles each year to visit Yosemite or the Grand Canyon or the
North Cascades will find little enjoyment if, for example, upon
reaching the Grand Canyon it is difficult if not impossible to
see across the great chasm. if that were to come to pass - and
several of our great national parks, including the Grand Canyon,
are threatened today by such a fate - the very values which
these unique areas were established to protect would be irre-
parably diminished, perhaps destroyed. Former Secretary of
Interior Rogers Morton recognized the value of these lands and
their threatened loss when in June 1973 speaking of the national
park lands in the southwest, he stated:
The scenic beauty of the rugged Southwest land-
scape, coupled with the clarity of the air in the
vicinity, are national assets of major importance,
worthy of protection for the enjoyment of future
generations of Americans.
Unless a policy of prevention of significant deterioration
of air quality provides special protection for these national
lands belonging to all Americans, their beauty may be lost
forever.
9
-------
1 980 Visibility Regulations
On December 2, 1980, the Environmental Protection Agency promulgated
regulations' to Tmplement the Clean Air Act's visibility protection provisions.
Key provisions of these regulations include:
a) Phased Approach - The regulations recognize two distinct
types of air pollution which impair visibility:
4 • • -*
1) smoke, dust, colored gas plumes or layered
haze emitted from stacks which obscure the
sky or horizon and are reasonably attribu-
table to a single source or a small group
of sources, called "plume blight"; and
2) widespread regionally homogeneous haze from
a multitude of sources which impairs visi-
bility in every direction over a large area,
called "regional haze."
Because of ". . certain scientific and technical
limitations . . ." EPA promulgated a phased
approach to visibility protection regulations.
Phase I of2the program requires control of
impairment that can be traced to a single
existing stationary facility or small group
of stationary facilities.3
b) BART Analysis/Re-analysis and implementation -
The States must perform a "Best Available Retrofit
Technology" (BART) analysis on any appl icable
existing source to which the State can reasonably
attribute (through visual observation or other
monitoring technique) visibility impairment in
any applicable Class I area or integral vista.
In the Bart Analysis, the States determine what
additional controls, if any, are needed on the
sources of existing impairment in order to remedy
or reduce the visibil ity impairment.
In this analysis, the States should consider the
cost of control, energy and environmental impacts
of control, air pollution controls already in
place at the source, the remaining useful life of
the source, and to what degree the control alter-
natives would improve visibility.
c) New Source Review - The regulation also requires the melding of
the visibility protection requirements of Section
165(d) with those of Section 169A, for purposes
of preventing new impairment resulting from pro-
posed major emitting facilities.
10
-------
Section 165(d) applies to air pollution impacts
within a Class I area and does not provide for
the balancing of economic, energy and other non-
air factors with air quality factors. Under
Section 169A, the States may weigh other factors,
such as economics, with protection of integral
vistas.
d) Long-Term'-'Strategy - The regulations require each applicable
State to develop and include in its State
Implementation Plan (SIP) a long-term (10 to 15
year) strategy for making reasonable progress
toward remedying existing and preventing future
visibility impairment.
In judging reasonable progress, the States may
weigh economics, energy, and other non-air qual ity
factors against improvements in air quality.
D. Issues
The overall issue is the value of visibility protection compared to the
cost, including air pollution control equipment and the regulatory system. Part
of the value of visibility is economic, expressed in many ways such as the extra
price people pay for homes with good vistas and the price people pay to travel
long distances to see vistas with high visual air quality. A related issue is
what people see when they look at a vista. What instrument measurement and
visibility-related variables describe visibility in a way consistent with hu-
man perception? How should vistas be presented to people in order to question
them about the economic value of visibility? These issues are the subjects of
on-going research. This study is based on the most up-to-date understanding of
these issues, much of which was developed by our research efforts.
E. Organization of the Report
Chapter 2 describes the photographs of vistas in the National Parklands
used in surveying people in four metropolitan areas about the value of pre-
serving visibility in National Parks. Chapter 3 relates the levels of air
quality shown in the photographs to regional industrial emissions under three
alternative scenarios. Chapter 4 reports on a study of the relationship
between perception of air quality by direct observation as opposed to that pre-
sented in slides and photographs. Chapter 5 describes the economic basis for
the survey design, which is presented in Chapter 6. Chapter 7 gives the survey
results while Chapter 8 develops an aggregate benefit measure for preserving
visibility in the National Parklands of the Southwest. The overall study thus
brings together work from atmospheric physics (Chapters 2 and 3), psychology
and sociology (Chapter 4), and economics (Chapters 5-8) to provide an esti-
mate of the benefits of preserving visibility in the Grand Canyon Region.
Only with knowledge of (1) how emissions effect visibility, (2) how people
perceive changes in visibility and (3) how people value changes in perceived
visibility in dollar terms can a valid estimate of such benefits be made.
1 1
-------
REFERENCES
1. 45 FR 8008 4 December 2, 1980.
2. Impairment - Visibility impairment is defined as "any humanly perceptible
change in visibility (visual range, contrast, coloration) from
that which would have existed under natural conditions."
3. EPA has determined ". . . that the present mathematical models and moni-
toring techniques show promise for being used in regulatory manner. However,
these techniques must be further evaluated . . . ." Teleradiometry and
photography are two visibility monitoring approaches that have been widely
used over the past three years.
12
-------
CHAPTER 2
REPRESENTING VISIBILITY WITH PHOTOGRAPHS
A. Photographs Used In The Survey
During the summer of 1980, over 600 people in Denver, Los Angeles,
Albuquerque and Chicago were shown 5 sets of photographs depicting regional
haze, each set consisting of 5 photographs of a national park vista with
different visual air quality. The vistas are from Grand Canyon, Mesa Verde
and Zion National Parks. The observation sites, vista names and specifications
are given in Table 1. Summer visibility conditions were chosen for the survey
because it is the season of peak park visitation.
These photographs were placed on display boards as full frame 8 by 10 inch
textured prints, arranged from left to right in ascending order of visual air
quality with each vista a separate row (see Figure 1 representing visibility
at the Grand Canyon and F gure 2 representing visibility conditions throughout
the Grand Canyon Region). The participants were asked how much they would be
willing to pay for visibi ity as shown in the five sets of photographs.
Participants in the survey were also asked about their willingness to pay
to prevent a plume from being seen in a Class I area. Two photographs were
used, one with and the other without a plume. The photographs were taken from
Grand Canyon National Park at the Hopi firetower observation point and towards
Mt. Trumbull (west). These two photographs, shown in Figure 3, were both
taken at 3 a.m. so the lighting on the canyon wall and other features are the
same. Both photographs have the same light high cirrus cloud layer.
The plume is a narrow gray band crossing the entire vista in the sky, except
where it is in front of the top of Mt. Trumbull. We believe the source was a
controlled burn near the Grand Canyon. The photograph specifications are in
Table 2.
B. Data Base
The photographs were taken with a 35mm lens on single lens reflex auto-
matic exposure came-ras at Grand Canyon, Mesa Verde and Zion National Parks
during the periods shown in Table 1. These cameras are operated as part of the
photographic program in the EPA/NPS regional visibility monitoring network.
The network also provides teleradiometer measurements of the apparent green
contrast of targets viewed from these parks, from which standard visual range,
attenuation coefficient and other visibility-related variables are computed.
The apparent green contrast is measured on each slide with a manual multiwave-
length teleradiometer. To do so, the slide is projected on a screen and the
apparent green radiance N is measured on the target used in the network and
the adjacent sky. The apparent contrast C, is computed with equation (2) from
13
-------
Table 1
Vistas for Survey
Park
Observation
Site
Vista
Direction
(°true)
Time of Day
(Loca1)
Target
Distance
(km)
Period
Photographed
Grand
Canyon
Hopi Point
Desert View
96
9AM
30
Oct.
79 to
present
Grand
Canyon
Hopi Point
TrumbuII M t.
293
9AM
96
Oct.
79 to
present
Grand
Canyon
Hopi Point
Trumbull Mt.
293
3PM
96
Oct.
79 to
present
Mesa
Verde
Far View
Visitor Center
Shiprock and
Lukachukai Hts.
208
9AM
6 8 to
Shi prock
130 to
Lukachukai
Ml t s., T a r g e t
Nlumber 1
Oct.
79 to
present
Zion
Lava Point
Trumbull Mt.
I 90
10AM
105
July-November 1979
-------
GRANDCANYON
VISIBILITY
C
OPI PT.
EST pm
HOPI PT.
WEST pm
-------
GRAND CANYON
is**:.!* XS*f&'y-~ r:- -
*
¦* »A"«WM|p
•-
A
PLUME ANALYSIS
B
-------
Figure 2
Regional Photograph Board
-------
Table 2
Photographs for Plume Question
Photograph
Archive #
Date
iime(Mb I)
Cloud
4
without piume
wi th plume
GC 395
GC 405
2 7 Nov. 197 9
2 8 Nov. 197 9
8:5o a.m.
9:20 a.m.
Cirrus
Cirrus
Table J
Target Specifications and SI Ides for Summer 1980 Survey
Target
Observation
Site
Time of Day
(local time)
C
o
_¦]
aR(km )
r (km)
Photograph
Archive
Number
C
r
f(% y
(aa)
*fn S*
TrumbulI
Hopi F J re
Tower,
Grand Canyon
9AM
-.735
.10327
96
GC 84
GC 92b
Med 1 an
GC 171
GC 268
GC 204
-oh
-.10
-.12
-.20
-.26
-.30
8
35
50
92
99
99.9
21
2.30
1.92
0.86
0.3*
0.01
TrumbulI
Hopi Fire
Tower
Grand Canyon
3PM
-.8
.00927
Sf
GC 519
GC 102
Median
GC s36
GC 313
GC 54s
-.08
-.Ik
-.17
-.18
-.2*1
-.30
9
30
50
55
85
97
2. gt,
I. 78
1.37
1.25
0,6s
0.19
Oesert View
Hop! Fire
Tower
Grand Canyon
9AH
-.88
0093*9
30
GC 9
GC 501
GC 9*
Median
GC 3H
GC 406
-.26
-.37
-.1»3
-.*5
-.59
-.71
I*
23
50
90
99. 1
6.26
3.91
2.90
2.6o
0.80
0
.ukachuka I I
ihiprock View)
Far View
Visitor
Center,
Mesa Verde
9AM
-.7
.009076
106
MV 54
MV 48
MV 133
Med 1 an
MV 23*»
MV 21
-.02
-.04
-.08
-.10
-.14
-.24
3
8
32
50
89
99.99
4.89
3.59
2.28
1.86
1.22
0.20
Trumbul i
Lava Point ,
ZIon
10AM
-.82
.009181
105
2 2
z
Med Ian
2 190
2 119
2 146
-.02
-.07
-.12
-.15
-.18
-.24
50
5.24
2.85
1.82
1.40
1.05
0.50
'umulat I ve frequency ( less than or equal ) of occurrence of spec! f led target apparent green cent rast
''Med Ian of measurements taken during Sunnier 1 9 7 9.
18
-------
Appendix A which gives a summary of the theory of visibility applicable to
this study.
It is important to know the frequency of occurrence of the photographed
visual air quality at each of the vistas. The cumulative frequency of the
apparent contrast of the official network target in each photograph is computed
from teleradiometer measurements taken during summer 1979 (see Table 3). The
5 photographs for each vista were chosen to have perceptible differences
(Maim, et al. 1980a), between adjacent pairs, and the middle photograph is
nearest the median visibility observed during summer 1 979. Only the Mt. Trumbull
morning series is slightly skewed, with the observed median being closer to
the second photograph.
19
-------
CHAPTER 3
REGIONAL EMISSIONS AND VISIBILITY
A. Introduction
The principal objective of this study is to measure the benefits
of preserving visibility. However, benefit measures associated with ambient
air quality must be related to emissions by industrial sources so that a
comparison of benefits to control costs can be made. This chapter, along
with Appendix A, provides the basis for relating benefits to industrial
emissions.
B. Relating Visibility to Emissions
The apparent target contrast, C„ distance between the target and observer,
r, and inherent green contrast, C., of the target allow us to compute the mean
attenuation coefficient, a, of t8e sight path, using equation (11) from
Appendix A.
1 c
a = —1 n^- (1)
r
The mean attenuation coefficient comprises three parts, contributed by fine
particulate, NO^ and the normal gaseous constituents of air, so that
a ¦ afp * aN02 * aR (2)
'here af = fine Part'cu^ate attenuation coefficient (km-'),
aN0 = NOjattenuation coefficient (kin j'and
= sight path weighted Rayleigh attenuation coefficient (km-').
Only the fine particulate is shown here, rather than total particulate, because
the fine particulate dominates the coarse particulate contribution to visi-
bility (Macias, et a I . , 1 979), except possibly in dust storms.
In order to evaluate the relative magnitude of cx^q , information is needed
2
on its concentration in clean air and the attenuation per unit path length and
per unit concentration. The attenuation coefficient for a gas that absorbs
light much more than one that scatters light is given by:
a = A = aC
where A = absorption coefficient (km '), a = absorptivity (km'mole liter')
and C = concentration (liter mole-'). Background concentrations of N02in the
Southwest are about 6 parts per billion (Walther, et a]., 1978) and the absorp-
20
-------
tivity (Hall and Blacet, 1 95 2) at,550_tjim is 31.1 mole cm , hence the NO
absorption coefficient is 8.3*10 km ._^ 1 n comparison, a typical RayleigR
attenuation coefficient is about 10 Km , over one magnitude larger. The
fine particulate attenuation coefficient is usual ly at 1 east as large as the
Rayleigh attenuation coefficient (Maim, et a I., 1980c), and hence also over
one magnitude larger than the N0^ attenuation coefficient. Therefore, we
assume the nitrogen dioxide concentration is low enough, so that
a-a^. + a.
fp • R. (3)
Combining (1) and (2), we get
i c
1. o
a r ct _ = ~ I rhr—
fp R r C
r r
o r
¦ 'lri. *
ac ~ 1 rh; aD ...
fp r C R. (4)
r
We know for the sight path because we know the elevation of the observation
sites and each target.
A constant of proportionality, k, between fine particulate attenuation
coefficient and concentration, was derived by others (Macias and Husar, 1 976):
"fp ¦ k*fp (5)
~3 "1 "3 -1
where k = 5*10 km (ygm ) and
X^p = fine particulate concentration (ygm ^) .
In the EPA/NPS regional visibility network, standard visual range (SVR)
is computed with the relation
SVR = _3;912— (6)
a-a^+.0l
Combining (3) and (6),
svr1. hm— (7)
% * 01
and combining (5) and (7), we get the equation for k as a function of SVR and
X V
, _ 1 3.912 . 1 ,n,
k " JT -svr ¦ 0 ' (8)
"fp , ,
21
-------
From the EPA/NPS network, computations for 191 ocati oris over 6 seasons from
summer 1978 through fall 1979 indicate anqveral 1 geometric mean standard visual
range of 165 km. If we assume Xf = 3ygm over the test region (to Ve
in Chapter 2B) and time period, tnen use of (8) leads to k = A.6*10 (ugm ) .
This agrees within 10% to the value found by Macias and Husar (1 97 6).
Using airport observations in the southwest, NASN (National Air Sampling
Network) data, and emissions data, the rate of change of attenuation coefficient
with S£> -emissions has Jaeen studied by Marians and Tr i jon i s (I 979) • We wi l I
define such a change by the coefficient b:
b ¦ da/dES02.
Because we assume that fine particulate dominates the variation of attenuation
coefficient, then da.
da-da, , so b =
fp
'fp' '
Solving for the change in fine particulate concentration as a function of changing
S 02emissions,
fife- ifE- . . b/k.
% 02 % 02 afp
Marions and Tri jonis (1979) found
^afn ^ -3 -] -1
Tp - 2• 10 km (1000 tons S02per day)
SO
^ X
If we let k = 5 0 1 C? k m'(ygm ^, then ,-^p = 0.4 ugm ^ (lOOOtpd S 02) 1 .
S~0,
This rough relationship is used here with projected changes in the S02emission
inventory affecting the region to estimate the resulting change in fine particu-
late concentration. It is a rough relationship because the regression analysis
used to produce the coefficient does not take careful account of different
categories of sources, the various mechanisms by which these sources lead to
ambient fine particulate concentrations, and the resulting attenuation coefficient.
We can derive an estimate of the fine particulate concentration prevailing
in a picture. Combining (4) and (5), we get
i i c
Y 1 n——¦ - a ) (9)
xfp ¦ k(r irX V *
r
22
-------
Equation (9) is used to compute the fine particulate concentration we
expect to be associated with each photograph used in the survey, assuming the
particulate concentration is uniform throughout the vista.
c. Emission Scenarios
Now we want to develop scenarios of future anthropogenic effects on vis-
ibility in a test region defined as southern Utah, southwestern Colorado,
northern Arizona and.northwestern New Mexico (see Figure 4). One of the impor-
tant driving forces will be the increase in energy related activities, including
coal mining, coal combustion to generate electricity, coal conversion to liquid
and gaseous fuels and the diverse activities of new people moving into the
region.
All these activities create pollutant gases and particulate, some emitted
in the region and some transported into the region from similar activities
upwind. Fully recognizing the possibility that other sources may be more
important, we will arbitrarily simplify this complex set of sources and pollu-
tants by focusing on only coal-fired power plants, the S02they emit and the
resulting sulfate fine particulate that affects visibility. This approach seems
justified in this specific test region because the proposals for coal-fired
power plants there far outweigh the proposals for other major sources of air
pollution in the same region (Walther and Coma row, 1 979).
The scenarios are developed for sources that are proposed to be constructed
by 1 990-1 995, because information from various energy projections is available
only to this future time period.
Scenario 0
There may be no appreciable change in S02emissions (EPA, 1979; Mitre
Corp., 1979) because the increase in power plant emissions may be offset by the
decrease in smelter emissions. If we assume natural S02emissions also do not
change, then we are led to a projection of no change in sulfate fine particu-
late. If we also assume that sulfate dominates fine particulate, then we pro-
ject no change in ambient fine particulate concentration, hence no change in
the attenuation coefficient of fine particulate. There wouId be no change in
apparent contrast of any target in the test region. This 'no change' scenario
provides no basis for asking people about the economic value of a regional
change in visibility related to energy development.
Scenario 1
In order to develop a scenario based on a definite change in emissions, the
the smelter emissions contributing to the test region are assumed to rema i n
constant.
In the test region the current major sources of S02are listed in Table
4. All these sources are coal-fired power plants.
The size is given as a range where various sources of information differ.
23
-------
UTAH
Figure 4
Test Region
ARIZONA
State
County
State
County
Arizona
Colorado
Apache
Cocon i no
Mohave
Navajo
Yovapa i
Archuleta
Dolores
La Plata
Montezuma
San Juan
New Mexico
Utah
San Juan
Rio Arriba
McKinley
San Juan
Kane
Washington
I ron
Garfield
Wayne
Emery
Grand
24
-------
Table 4
Current Major S02 Emissions In Test Region
Su
N>
VJ1
Power
Control
Leve 1
Emissions
Rate (tons r day)
Name
locat ion
1 i t
(mw)
(*)
b90'
>90'
'7:«'
22-4o
22-4o
Four j
Corners
Jrtland, NM
1
2
3
4
5
190
190
245
778
778
65
65
0
0
0
8.5-20.5
8.5-20.5
10-24
90-160
90-160
35
35
<•0
160
160
Hunter
(Emery)
astle Dale, UT
1
2
00(H)-') 30(G)
001 N)-i| 30(G)
80
80
7
35
26
26
2
lunt i ngton
Huntington, UT
1
2
400
A15
80
80
21.5
21.5
26
26
Mohave
>u) 1 head City, AZ
1
2
82o
82o
0
0
40,463,502,64
40.46. s0.64
40-64
40-64
Navajo
'age, AZ
1
2
3
770
770
770
0
0
0
.5216
.5216
.5216
<¦6.7*. 55-7?, 81.3
46.73,55 74,81.3
46.73.55.7 .81.3
46.7-81.3
46.7-81.3
46.7 -81.3
CorOnado
it. Johns, AZ
1
50(N)-395(g)
66*
.816
38
113
q
Gardner
loapa, NV
1
2
3
110-130
110-130
110-130
80
80
80
16.7
16.7
16.7
83.3
83.3
83.3
3
San Juan
ruitland,NH
1
2
3
360
350
500
67
67-5
67
.55
.53
.55
22
21
35
67
65
1O6
TOTALS
23
units
692- 10?4
1398-1587
'ur Dioxide
N = net rating = gross rating minus on site consumption of power
G = gross ratinq
* = .8 of total flow Is controlled to 82 percent level
Sources:
(1) Roberts, Edwin, 1980, phone communication to Arizona Public Service Company, June 30; (2) Christian, John,
1980, personal coiiinunicat ion to National Park Service, Air Quality Office, June 2; (3) Cope I and, John O. , 1 979,
EPA memo to Steve E Jgst i , July 17', (4) Noon, Don, 1980, phone communicatIon to Salt Rive Project, July 9; and
(5) Syzedek, Laura, 1980, persona I commun I cat ion to Nevada Power Company, June 19.
-------
The two sizes are sometimes the net and gross ratings, respectively. Some refer
to maximum possible electrical output while others refer to the normal output.
These differences are small enough to neglect for the purpose of this study.
Each generating unit is listed separately because we must account for the great
variation of size, control equipment and S02emissions that sometimes exists
between units of the same power plant.
The controlled emission rate of S02 is reasonably well known for these
sources. A list of units proposed to operate by 1 990 is presented in Table 5.
The .projected S0„ emissions for these units are not so readily available.
Each ut i l i ty company was requested to provide emissions by phone or letter if
there existed no report with the information.
da d y _
Using the relations for f p and fp , the increase in controlled S02
dES02 dES02
emissions will cause the concentration of fine particulate to increase by
Ax^p = 0.19-0.20 ygm"3
This change is small, but must be translated into the change in apparent con-
trast of specific targets in order to judge perceptibility. Perceptible
changes are required in order to ask people questions about their economic
willingness to pay to prevent such changes. Selected locations and targets
are listed in Table 6 along with the information used to compute contrast change.
Equation 4 is used in the form
c . c.'N^,r
w r wo •
The change in the apparent green contrast between columns 7 and 8 of Table 6
cannot be perceived (Maim, et a I., 1 980a). This finding suggests that the addi-
tion of 392-410 tons of S02per day to this region would be insignificant to
visibility. For comparison, the 1979 S02emissions from copper smelters in
southern Arizona were 2 4ootons per day, almost 5 times as much (Billings,
1980) . Another approach is to compute an artificially larger scenario that
causes a perceptible change in contrast which could be used in a questionnaire.
Scenario 2
The current and proposed power plants for the test region will be supposed
to emit S02at the maximum possible uncontrolled rate. Direct particulate
emissions will continue to be controlled. The uncontrolled SJl emissions are
listed in Tables k and 5. The increased emissions would be 3692-4327 tons per
day. These uncontrolled S02emissions would cause Ax^ = l.48-1.73ugm ffver
the summer 1979 fine particulate concentrations listecP in Table 6. The changes
in apparent contrast shown in column 9 of Table 5 vary between .05 and .09, and
are perceptible changes (Maim, et a I., 1980a).
The actual photographs used in the summer 1980 perception/economic survey
are listed in Table 3 with information on the target name, time of day, inherent
26
-------
Table 5
Major S02Sources Proposed for Test Region by 1990
Sulfur Dioxide
Control
Level
S02 Emission K3tG
Unit
Power (™)
(pounds S02
(tons Der dav)
Name
%
per 10°BTU)
control led
'Jncontrol led
Harry Al len'
1
2
3
it
500
500
500
500
92
92
92
92
.17
.17
• 17
.17
1 0
10
ID
10
129
129
129
129
Sreen River
1000
90
.2
25
250
Werner Valley'
1
2
250
250
92
92
.17
.17
5
5
65
65
Sarfield
I
400
90
.2
10
100
Inter-Mountain
1
2
3
4
75o[J]!-82o|g! |
750^-820]^ I
750v -820
90
90
90
90
.2
.2
.2
.2
18-20
18-20
18-20
18-2o
184-2oo
184-200
184-200
i84-2oo
Hunter
3
4
400430
400430
90
90
.2
.2
10
10
100-106
100-106
Colorado
i
250
90
.2
6
61
:holla
3
i»
5
242-289
350-375
350-375
90
90
90
.06- .07
.07
.07
2
]2
20
30
30
Soronado
2
3
350-395
350-395
66'
66
•8j"9
381'\-^
38z,3-iO
113-127
113-127
Spri ngervi I le
1
2
3
350
350
350
60
60
8
.6
.6
.25
2.it
25'
2A";
10?
62.5
62.5
6I
MOOn I ake
800
90
.2
20
200
San Juan
4
500
67
.55
3 5
106
Plains
Electric
I
210
90
.2
5
50
New Hexi CO
G.5.
1
2
3
4
500
500
500
500
80
80
80
80
.34
.34
.34
.34
21
21
21
21
105
105
105
105
Reid Gardner
'~
250-295
85
.14-. 16
10
67
Tota s
33 units
12,704-13,480
48 I -t>99
3328-3432
a0n i y 80 percent of total flow is directed through wet scrubbers with 82 percent control
N — net
G = gross
Sources:
(1 ) Syzedek, Laura, 1980, persona I commun i cat ion to Nevada power company , June 19; (2) Energy impact
Associates, 1979, Update Report; (3) Noon, Oon, 1980. phone communication to Salt Rive Project, July 9;
and (4) Fleck, Lowell, 1980, pnone communication to Tucson Electric Power Company, July II.
27
-------
Table 6
Apparent Green Contrast Chan9e Co be Caused In Test Region by Proposed Sources of SO^
Median Fine Particulate
Concentration (|igm
Median Apparent Green
Contrast
iyju-
99s»-l
395
Location
larget
1 (me
or Day
Summer
19/9
Scenario 1
Scenario 2
Summer
1979
Scenario 1
Grand
Canyon
Trumbul1
Mountain
9
a.m.
1.92
2.12
3. <10-3.65
-.12
-.11
-.06,-.05
"
"
3
p.m.
1.37
1-57
2.85-3.10
-.17
-15
-.08,-.07
ii
Desert View
9
a.m.
2.60
2.80
4.08-4.33
-.45
-.44
-.36.-.35
Mesa
Verde
Lukachukai
#1
9
a.m.
1.86
2.06
3.34-3.59
-.10
= ; 09
-.05,-.04
Z ion
Trumbul1
Mountain
9
a.m.
1.82
2.02
3.30-3-55
-.12
".II
-.06,-.05
-------
contrast, Rayleigh attenuation coefficient, distance between the observer and
the target, archive number, apparent contrast measured with a teleradiometer
on the slide image projected on a screen, and the associated fine particulate
concentration.
The regional analysis of the change in visibility from the current (summer
1979) median to the 1990 uncontrolled S02 emissions used the slides listed in
Table 7, whose specifications are listed in Table 3.
D. Conclusions
The photographs collected in a regular photographic monitoring program over
a period of at least half a year are numerous and varied enough to provide sets
for surveying purposes. The photographs can be presented as slide images on a
screen (Maim, et a I., 1980a) or as prints. The frequency of occurrence of each
photograph can be computed roughly from the photograph collection (Walther and
Carey, 1980) or from the set of teleradiometer measurements of the apparent
green contrast of a target in the scene. The apparent green contrast of the
target in each photograph differs from the adjacent photographs in its subset
by .02 to .12. These differences are perceptible, but they are not uniform
because the photographic monitoring period was not long enough to produce every
desired apparent contrast with the constraints of blue sky and no snow on the
target. Photographs with these constraints and with perceptibly different con-
trasts allowed people to be questioned about the economic value of different
visual air quality.
The locations of the EPA/NPS regional visibility monitoring program cameras
and teleradiometers constrained the region that could be chosen for the scenarios
of future changes that may affect visibility. The test region represents an
area where good visibility is probably necessary for the high social value
people place on the region's many national parks and monuments. Coal-fired
power plants are the most numerous future sources of air pollution proposed for
this test region and they have been the most controversial air pollution sources
in the past history of this region. Because fine particulate is the single
most important kind of pollutant affecting visibility in this region (Waggoner,
et al., 1981) and because S02emissions are the most important contribution to
fine particulate, (White and Roberts, 1 977) visibility will here be directly
related to S02emissions. This relationship was developed by others on the
basis of airport visibility observations and the S02emission inventory his-
tory of the southwest (Marians and Trijonis, 1 979). As such it is a rough
model, but it is consistent with the roughness of the economic information
obtained by asking-people how much they would be willing to pay on their monthly
power bills to protect visibility.
One scenario of the future suggests no deterioration of visibility
because smelter S02emissions near the test region may decrease more than the
S02emissions may Increase from proposed coal-fired power plants. This scenario
provides no basis for the survey process. A second scenario based on the
actual S02emissions expected from the proposed power plants suggests there will
be no perceptible deterioration of visibility, again providing no basis for a
survey. The third scenario is hypothetical, based on the totally uncontrolled
29
-------
Table 7
- . Slides in Regional Scenario of
Uncontrolled S02 Emissions
SI ides
Location
Target
Current
Median
1990 Scenario
Uncontrolled S02
Zion
Trumbull Mt.
Z190
z1 6
Mesa Verde
Lukachukai 1
MV133
m v4 8
Grand Canyon
Desert View
GC94
GC 501
30
-------
release of allSO,, that can be created from the sulfur in the coal for both
existing and proposed power plants. The r,egression-based relationship of visi-
bility and S0„ emissions i s combi ned wi th thi s hypothet i cal scenari o to compute
a percept ible deteriorat ion of visibility from the middle photograph of each
vista to the next worse photograph. This change allows comparison of the
value of the visibility increment to the cost of air pollution equipment
needed to reduce the uncontrolled emissions to the actually projected level
of control.
4 . ...
All three scenarios of future S02emissions in the test region should be
recomputed with the use of a long range transport model, allowing for: 1) the
transport of distant emissions into the region; 2) the chemistry of S02con-
version to sulfate fine particulate; 3) the removal by dry and wet deposition
of pollutants affecting visibility; and 4) the inclusion of smelter and urban
emissions.
31
-------
CHAPTER 4
PERCEPTION OF VISIBILITY
A. Introduction
Valuing visibility in economic terms requires a clear understanding of
how people perceive visual air quality. This chapter summarizes our current
understanding of perception of visibility and presents some new results of
a study utilizing photographs similar to the ones used in the economics portion
of the study.
Visibility is commonly interpreted as visual range, which roughly
speaking, is the distance an observer would have to back away from a target
for it to disappear. Visual range cannot be measured directly, nor is it
necessarily representative of what an observer "sees." More importantly,
visibility involves human perception of color, form and texture of near and
distant natural structures.
0. Summary of Perception Studies
Characterization of visibility involves a selection of physical vari-
ables that can be directly measured and correlated with human perception of
changes in visual air quality. Previous field experiments have examined the
relationships between physical parameters of visibility such as apparent tar-
get contrast, color contrast, sun angle, and human perception of changes in
those parameters (see Maim, et a I., 1980a, 1980b). These studies also ad-
dressed human perception of changes in air quality as presented in different
media, comparing observer judgments of color slides, color photographs, and
the actual scene as viewed on-site.
The original study which examined these variables was conducted by the
National Park Service (NPS) and Environmental Protection Agency (EPA) at
Canyonlands National Park during the summer of 1 9 7 9. Visitors to the Island
in the Sky District of the park were asked to rate color slides representing
variations in air quality, sun angle, meteorological conditions, ground cover,
and landscape elenfisnts. It was assumed, a priori, that such variables would
be important factors affecting human perception 'of visual air quality. Thus,
these factors were specifically controlled so that the effect of changes in
air pollution on perceived visual air quality could be explicitly studied.
This approach may be contrasted to that of randomly sampling the joint occur-
rences of all of these variables and then, a posteriori, attempting to separate
their effects by means of statistical regression procedures (Latimer, et a I.,
1980) . Both approaches can make valid and valuable contributions to the under-
standing of visibility perception. Where a purely statistical approach may
have problems in explicitly extracting the targeted relationships between per
32
-------
ception of air quality and elect ro-optical parameters, it may achieve greater
generalization in predicting the effects of illumination and meteorological
conditions.
The study slides, all of the same scene, were chosen from over 1000 slides
taken throughout the previous year as a part of the NPS/EPA visibility moni-
toring program. At the time each slide was taken, teleradiometer readings of
apparent target contrast, color contrast, and various meteorological measure-
ments were made. Therefore, for each slide rated by visitors, the physical
and optical parameters of air quality were known. After viewing 10 preview
slides representing the full range of air quality conditions, v i s i tors rated
48 evaluation slides on a lto 10 scale, with 1 representing very poor visual
air quality and 10 representing very good visual air quality. Interspersed
with the 48 evaluation slides were 15 control slides used to determine the
precision with which each visitor used the rating scale. After rating the
slides, visitors completed a demographic questionnaire and were administered
a test for color-blindness. Finally, they entered a second room of the
survey trailer where they could view the La Sal Mountains through a window,
framed much like the slides. The visitors were then asked to rate the visual
air quality on that day as viewed through the window on the same 1 to 10 scale
used for rating the slides. A color slide and teleradiometer reading were
taken to correspond with each on-site rating. Later in the survey period,
these slides were shown to visitors, who again rated visual air quality on the
1 to 10 rating scale. Nearly 700 visitors completed the survey.
Studies similar to the Canyonlands study were conducted at Mesa Verde
and Grand Canyon National Parks during the summer of 1 980. The differences
i nc 1 ude:
- Where the Canyonlands study used only one scene, the 19 8 0
studies utilized several vistas located in different
national parks;
where the first study allowed visitors to rate a three
dimensional scene constrained by a window to mimic the
identical scene as viewed in the slides, the 1980 studies
allowed the visitor to rate physically unrestricted views
of a vista in the same general direction as the slides
were taken. These on-site ratings were then compared to
ratings (by other observers) of color slides;
- where the Canyonlands study reported results for all
visitors combined as a group, the later studies specifi-
cally investigated the effects of a number of social
and demographic characteristics on judgments of perceived
visual air quality;
where the 1979 study focused primarily on a determination
of a humanly perceptible amount of change in visual air
quality, the 1980 studies also examined social and economic
issues associated with changes in visual air quality;
33
-------
and, where the first study compared only visitors' judgments
of changes in air quality shown in color slides and the
actual scene, the 1980 studies compared visitors' judgments
of air quality represented in color slides, the actual
scenes, and color prints.
c. Study Results
Visitors used'the 1 to 10 rating scale with precision, as is evidenced
by their ratings of the 15 control slides used in the Canyon lands study. The
control slide mean rating (CSMR) for 50, 100, or 300 observers varied by less
than .01 and the mean of their standard deviations varied by less than 0.4.
Similar analysis of the evaluation slides shows almost identical results.
Generally speaking, slides with extremely good or extremely poor visual air
quality were universally rated the same by all observers. Slides which repre-
sented intermediate levels of visual air quality were more difficult to rate;
control slide ratings indicated that some observers tended to be extremely
precise and consistent in their ratings while others had more difficulty in
using the rating scale. It is important to note, however, that the average
rating given each slide by a series of observers did not change when those
observers with a control slide standard deviation (CSSD) of greater than 1.0
were eliminated from the data set, nor did the introduction of more observers,
beyond approximately 50, change the average rating given each slide.
There was, however, an ordering effect when a slide representing average
visual air quality was preceded by a slide representing extremely good or
poor visual air quality. This effect was minimized by reversing the order
of the slides half-way through the study period. Thus, a slide that initially
followed an extremely good or poor slide, would be evaluated first, normal-
izing the overall slide ratings.
There seemed to be little or no difference in the way observers with
different demographic backgrounds used the rating scale. However, a Z-score
analysis was carried out to minimize the effect of variations between indivi-
dual observers. This Z-score analysis then allowed for calculation of
Indexes of Perceived Visual Air Quality (iPV's).
Figure 5 is a plot of mean IPV's versus apparent target contrast, Cp,
at 550nm (as measured by a multiwavelength teleradiometer) for clear sky days
(99 percent confidence limits around the mean ,s i 0-11). The broken and
solid lines correspond to snow and tree covered scenes, respectively. It is
evident that the functional relationship between Perceived Visual Air Quality
(IPV) and contrast (Cp,) is linear. The correlation coefficients, significant
at the 99 percent colliidence level , between IPV and C for the six meteorolog-
ical and air quality conditions measured are presented in Table 8.
34
-------
Figure 5
Clear Sky /
>
a.
a
3
a
<0
>
•a
o
®
a.
X
®
~n
a
Morning
Afternoon
Snow on _ /
Mountain /
Snow free
Mkfclu n t a i n
0.1 0.2 0.3 0.4 0.5
Green Contrast of Pine
Graph of the index to Perceived Visual Air Quality (IPV) as a function of apparent target (tree covered
portion of the La Sal Mountains) contrast for the clearsky condition. Tf,e dotted and 3olid line are for
snow covered and snow free conditions, respectively while (•) AND (¦) indicate slides that were taken
in the morning and afternoon, respectively.
35
-------
Table 8. Correlation Coefficients between IPV and C.
G
Clear Sky
Cumulus Clouds
Overcast Sky"
Snow
covered mountain
0.93
0.93
0.94
Green
mountain
y • - »
0.90
0.98
0.93
This functional relationship can be expressed as follows:
IPV = mCG + b
where IPV is the Index of Perceived Visual Air Quality, Cg is apparent target
contrast (tree covered mountain in this case), b is the y-intercept, and m
is an index indicating the sensitivity of a given vista to changes in air
pollution. The sensitivity of a vista to the impact of air pollution, then,
is the slope of the IPV vs. X curve; the steeper the slope, the more sensi-
tive a vista is to increments? changes in air pollution. Upon comparison of
the slopes of the curves shown in Figures 5 , 6 and 7, it is clear that cumulus
clouds and overcast cloud conditions cause m to decrease; with m being the
lowest for the cumulus cloud condition. Clouds tend to obscure the effects
which increased air pollution has on perceived visual air quality.
Perceived visual air quality of a vista under clear sky conditions seems
to be most sensitive to changes in amounts of air pollution. In addition,
snow in a vista appears to increase the observer's rating of visual air quality
for all sky conditions. It should be noted that even though an observer's
rating of visual air quality increases with a snow covered mountain (indicating
greater scenic quality), the sensitivity of that vista to contrast change, and
thus air pollution, remains approximately the same for different meteorological
conditions.
It is important to understand that changes in apparent target contrast
due to increased air pollution are dependent on the amount of pollutants in
the existing atmosphere. In a clean atmosphere, a small increase in particu-
late concentration will cause a large decrease in contrast, while in a relatively
dirty atmosphere that same increase in particulate concentration may not be
perceptible. Figure 8 graphically shows the expected change iq contrast
resulting from additions of 2 micrograms per cubic meter (yg/m ) fine particu-
late (0.1 y - 1.0 y diameter particles) to atmospheres containing approximately
0, 4, 8 and l8yg/m3fine particulate as a function of vjsta distance. It has
been assumed that an attenuation coefficient of 0.01 km 'is equivalent to a
fine particulate concentration of 2 yg/m. It is clear in all cases that the
cleaner the existing atmosphere, the more sensitive it is to an incremental
increase in particulate loading.
Also, as shown in Figure 8 , the maximum sensitivity to incremental in-
creases in air pollution occurs at a vista distance of abouJj 60-100 kilometers
in a clean atmosphere. In an atmosphere containing l8yg/m particulate
this distance of maximum sensitivity decreases to 10 kilometers.
36
-------
Figure 6
>
Q.
= 3 51 Cumulus Sky ¦
Morning
¦ Afternoon
§ 3.0 ¦
'-~-Snow on Mountain
< 2.5 -
/*
Snow free Mountain
.2 2.0 -
Snow free Mountain
0.5-
T>
0.0 O.I 0.2 0.3 0.4 0.5 0.6 0.7 0.8
Green Contrast of Pine
Same as Figure 5 but for cumulus cloud conditions.
Figure 7
> 3.5
Overcast
. Morning
• Afternoon
.h 2.5
Snow free Mountain
I.O
0.5
0.0 0.1 0.2 0.3 0.4 0.5 0.6
Green Contrast of Pine
Same as Figure 5 but for overcast cloud conditions.
37
-------
Figure 8
0.3 "
0.2 "
1.0
XfpsQ*jq/m3
Z/m 3
0.0
Srn3
11 i i i
20 40 60 80
Distance (km)
100 I20
A plot of contrast change resulting from an increase in
fine particulate concentration of 2 ug/m3 as a function
of vista distance for initial loadings of 0.0, 4, 8 and 18
ug/m3.
Figure 9
3.5-
3.0
2.5
2.0
1.5
[-0
0.5
0.0
• Morning- Snow free mountain
¦ Afternoon—Snow free mountain
A Morning-Snow on mountain
~ Afternoon—Snow on
mountain
0.0
0.2 0.4 0-6 0.8
A
= Difference in color contrast of VISTA (X 10)
Graph of I PV versus change in overall vista color.
Indices of perceived visual qir quality presented in
this graph, were derived from visitor's ratings of
the morning and afternoon, snow, and no snow,
clear sky conditions.
38
-------
Results of the Canyonlands study also indicate that any increase in
color of the total vista results in increases in the IPV. The change in over-
all color contrast, AC_, for each slide was plotted against the IPV, indicating
the 1 inear relationship shown in Figure 9. The observer rated the visual air
quality of a scene in direct proportion to the amount of color present.
Sun angle plays an important role in vista color and observer's judg-
ments of visual air quality. Visitors were asked to rate a series of slides
of the La Sal Mountains which were taken starting at 8:00 a.m. and continuing
until A:00 p.m. The air pollution as measured by a teleradiometer and an
integrating nephelometer remained unchanged throughout the day. The canyon
walls in the mid-foreground of the scene were in complete shadow at 8:00 a.m.
The color of the canyon walls continually increased as the day progressed and
the sun angle changed. As more color appeared in the scene, observers gave it
a higher rating of visual air quality. Figure 10 shows this relationship,
plotting the mean slide rating (raw score) for 50 observers as a function
of color contrast for the green portion of the La Sal Mountains. Time of day
is indicated next to each data point. During the course of the day, the con-
trast at 550nm actually decreased because of a decrease in inherent contrast,
while the mean rating of the slides increased. However, the relationship
between change in color contrast and perceived visual air quality remains lin-
ear. The correlation coefficient between these two variables is greater than
0.9, significant at the 99 percent confidence level. This relationship also
appears to be independent of the demographic characteristics of the observers.
Once these physical and perceptual relationships are established, it is
important to analyze the relationships between human perception of changes in
visual air qual ity as represented in different media. Do observers perceive
changes in visual air quality in an actual on-site situation with the same
precision as they would perceive the same amount of change as shown on a color
slide? In order to examine this question, visitors in the Canyonlands study
rated 40 slides that had been taken during on-site ratings earlier in the study
period. The optical and meteorological data for the approximately 400 on-site
ratings were inspected to locate cases representing sun angle, meteorological
and air pollution conditions as near as possible to those in each of the 40
slides. For some slides, several corresponding on-site ratings were found.
A student t-test was used to determine whether the slide ratings were statis-
tically different from on-site ratings. Since the test was applied to the null
hypothesis that the two samples being compared were drawn from the same popula-
tion, calculations were made to determine the probability of the difference be-
tween means of on-site and slide ratings having a value as large as, or greater
than observed. The null hypothesis being examined assumed that the two samples
belong to the same population, consequently, the two variance estimates must
not be significantly different. This hypothesis was examined by means of the
F-test.
Results of the comparisons are summarized in Table 9 while a scattergram
of the on-site and slide ratings is shown in Figure 11. The first column of
Table 9 gives the time that the slide was taken; it is also the time, +30 min-
utes, that the on-site ratings were made. Column two is a meteorological code
indicating the cloud cover present at the time the photograph was taken;
39
-------
Figure 10
8
26
to
5 *
o 5
tr
a>
.5 4
o
cc
§3
0>
4:00 P.M.
-------
Table 9
Statistical Analysis of On Site and Slide Ratings
Time
Sky
Code
Green
Con t.
Slides
O n
Site
Tests
Nobs
Mean
SD
95%-CL
Nobs
Mean
SD
95%-CL
T
T(Crlt)
F
F(Crlt)
1000
2
.34
22
3.1
1.6
.66
8
3-5
1.9
1.36
.574
2.05
1.451
2.4
1030
1
.40
208
A.5
1.7
.24
13
b.5
1.5
.84
.080
1.96
1.27h
2.1
1100
0
.38
45
3.8
1.2
.37
10
4.5
1 .It
.86
1.631
2.00
1.273
2.8
1100
2
.33
22
«t.5
1.7
.71
17
4.7
1.9
.94
.354
2.00
1.287
3.0
1130
1
.36
45
1.2
.37
21
4.7
1.1)
.60
.944
1.96
1.329
l.k
1130
2
.34
22
k.3
l.li
.59
18
5.2
1.8
.86
.523
2.00
1.696
2.8
1130
5
.34
22
4.8
1.3
.57
9
4.8
1.6
1.04
".041
2.05
1.446
3.35
1130
4
.19
22
3.7
I.I
.48
9
4.3
1.1
.75
1.449
2.05
1.033
3.35
1330
2
.30
208
6.5
1.8
.25
15
6.o
2.1
1.07
1.029
1.96
1.323
2.o4
1330
2
.33
208
7-5
1.8
.25
23
7-5
I.I
.45
.057
1.96
2.769
1.79
1400
0
.36
45
6.5
\.k
.42
13
8.1
1.0
.53
3.802
2.00
2.153
2.66
1400
0
.35
160
7-5
1.6
.26
8
7.3
-9
.63
.438
}.96
3.258
2.51
1400
0
.35
160
6-7
1.7
.27
8
7.3
.9
.63
.907
1.96
3.678
2.51
-------
Figure 11
Average perceived visual air quality ratings of 13 different three-dimen-
sional scenes are plotted against corresponding ratings of slides that
represented those same scenes.
§
>
-o
a)
>
'3
u
w
M
CD
a.
0)
c
O
Slide Perceived Visual Air Quality
42
-------
0 = cloudless skies; 1 = no clouds in the plane of the observer, Sun, and vista*
2 = O to 1/3 cloud cover; 3 = 1/3 to 2/3 cloud cover; 4 = 2/3 to full cloud
cover; and 5 = overcast. Column three is the apparent target contrast at
550nm of a forested section of the La Sal Mountains on the day when the slide
was taken; it is also the apparent target contrast +0.01 of that same portion
of the vista on the days that the three dimensional-on-site ratings were made.
Columns four to seven are the number of observations, arithmetic mean, standard
deviation, and 95 percent confidence interval of the slide ratings, and columns
eight to eleven give the same statistics for the on-site ratings. Columns
twelve and fourteen are the t and F statistic while columns thirteen and fif-
teen are the associated "critical" values which the t and F number should not
exceed for a 5 to 1 percent level of significance respectively. These calcula-
tions were carried out only if there were at least 8 on-site ratings.
An examination of the F-test shows that of 13 populations that were
compared, the F value exceeds its critical value 3 times. For the remaining
10 populations the difference between the variances is not significant at the
one percent level. If the calculated t value is greater than the tabulated
critical value (5 percent level of significance), the null hypothesis is
rejected and the conclusion is that the difference between the on-site and slide
rating is significant. Or conversely, if the value of t is less than the
critical value it is concluded that there is no statistically significant
difference between on-site and slide ratings. In only one case is the calcu-
lated t value greater than its associated critical value. Thus, there are 9
comparisons of on-site versus slide ratings that show no significant difference
between their means.
The previous statistical tests do not prove that the means of on-site
and slide ratings are the same, only that they are not statistically different.
However, the analysis in conjunction with a fairly high correlation of 0.94
between the on-site and slide ratings and the close proximity of the data
points to the line that shows where they would fall if there were a one-to-
one correspondence, seems to indicate that when the actual scene is confined
to the same form as that of the slides, slides are good substitutes for the
actual three dimensional scenes.
For research design purposes, it is also important to know if observers
perceive changes in visual air quality as shown in color prints with the same
precision as they perceive changes shown on color slides. In the 1980 Grand
Canyon study, groups of observers were asked to rate sets of 30 randomly
ordered 8 X 10 inch color prints on a 1 to 10 scale. Two sets of photographs
were rated; one set- contained Mt. Trumbull scenes under differing ground
cover, meteorological and air quality conditions, while the other photographic
set contained Desert View scenes under varying meteorological and air quality
conditions (the Desert View data set did not contain any scenes with snow on
the ground). Groups of observers rated the sets of 30 color slides from which
the photographs were made. Mean ratings for all slides in each set were then
compared to the mean ratings for each color photograph for groups of at least
50 observers. Comparisons were made by regressing the slide-based ratings
(mean ratings on the 1 to 10 scale) on the ratings of the corresponding color
photographs. Again, the relationship is a positive one, as indicated by a
43
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simple correlation coefficient of .96, significant at the 99 percent confidence
level, between the slides and corresponding photographs used in the economic
analysis.
D. Conclusion
These positive relationships of human perception of changes in visual
air quality, whether viewed in a color slide, color print or on-site, allow
for different research methods. It appears that it may no longer be necessary
to conduct air quality perception research only in on-site situations. This
finding enables researchers to conduct air quality perception studies in
other environments throughout the country, with substantially' reduced costs,
but more importantly, allows for a statistically random sample of observers
which is not possible in on-site studies. It is important that researchers
continue to examine these relationships in order to develop a valid model
for the prediction of air pollution and scenic quality effects on perceptions
of visual air quality.
44
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CHAPTER 5
MEASURING THE ECONOMIC VALUE OF VISIBILITY
A. Introduction
Visibility is a pure public good as described by Samuelson (1954). The
goal of Congress in passing the prevention of significant deterioration (PSD)
amendments to the Clean Air Act was, in great part, provision of visibility i n
the National Parklands. However, utilities and other industries have claimed,
quite correctly, that preservation of visibility (air quality) is costly. Do
the benefits of preservation justify these costs? The purpose of this chapter
is to provide a methodology for assessing the benefits of preserving visibi-
lity so that the question posed above can, in part, be answered.
Economists have used a number of techniques for valuing public goods.
These include, first, direct costing wherein, for example, benefits of air
pollution control could partly be measured as the reduced economic damage to
material (e.g., paint), vegetation (including agriculture) and health (e.g.,
inure productive workers). A second technique called the hedonic approach uses
an indirect method to value public goods by trying to associate changes i n
market prices with changes in public goods across locations. Thus, urban pro-
perty value studies are typically utilized in areas of heavier air pollution.
One can get an indication of how people value clean air by looking at the pre-
mium paid for homes in clean air areas. Both of these methods are described
in detail by Freeman (1979) and MSler (1974) but are not applicable to valuing
visibility in rural recreation areas such as the National Parklands of the
Southwest.
To develop value in such a situation, economists have turned to survey
methods . A large literature has developed around the use of survey techniques
in valuing visibility which includes, in part, early work by Randall, et al.
(1 974) and Brookshire, et al. (1976), and more recently work by Rowe, et al.
(1 980) and Brookshire, et al. (1 980). This literature has been summarized in
Schulze, et al. (1981) so we will not go into great detail here. However, it
has been shown that-survey techniques do provide willingness to pay measures
for air quality in an urban setting (Los Angeles) consistent with results of
a hedonic property value analysis, lending support to the survey approach
(see Brookshire, et al. [ 1 9 8 2 ] ) . This last study is included as Appendix B.
Additionally, survey work with consumers has failed to show any evidence
of strategic bias (Schulze, et al. [1981]) in valuing public goods. This
result is in agreement with the work of Grether and Plott (1973) and Smith
( 1 9 7 8 ) which also failed to find evidence of strategic economic behavior in
experimental settings. A number of other biases which have long been recog-
45
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nized in the survey literature have been identified, but standard techniques
developed in the political science, psychology and sociology survey literature
have been employed to cope with them (see description of the survey procedure
in the next section).
B. The Theoretical Basis -The Economics of Preservation
The goal of the PSD regulations is preservation of the natural environ-
ment. An integral part of the environment of the national parklands of the
southwest is visibility, the ability to see both color and detail clearly over
long distances. It has been shown that human perception of visual air quality is
associated with the apparent color contrast of distant visual targets. A s
contrast is reduced, a scene "washes out" both in terms of color and in the
ability to see distant detail. Chapter 3 has related decreases in apparent
color contrast to air pollution, noting, of course, that only part of the
regional air quality situation is attributable to identifiable man-made air
pollution. Chapter 4 has quantified perception of visual air quality. We now
attempt to specify how people value preservation of perceived visual air quality.
The existing literature in environmental economics suggests that pre-
servation value has two possible components.
First, a scenic resource such as the Grand Canyon attracts large numbers
of recreators. The quality of the experience of these recreators depends in
great part on air quality, in that scenic vistas are an integral part of the
Grand Canyon "experience". Thus, air quality at the Grand Canyon is valuable
to recreators. We might call this economic value, or willingness to pay for
air quality at the Grand Canyon that enhances the qual ity of the recreation
experience, user value. Thus, recreators in the National Parklands of the
Southwest should be willing to pay some amount to preserve air quality for each
day of their own use if their recreation experience is improved by good air
quality. Total annual user value is then, simply, the total number of annual
users times the average number of days spent in the parklands by each user per
year times the average value to users of preserving visibility per day. One
hypothetical market for collecting user value is an increase in entrance fees
to be used to finance preservation of air quality, i.e., purchase of air pol-
lution control equipment. Survey questionnaires can be designed to estimate
user value based on such a hypothetical market.
The second component of preservation value is termed existence value.
Individuals and households which may never visit the Grand Canyon may still
value visibility there simply because they wish to preserve a national
treasure. Visitors also may wish to know that the Grand Canyon retains rela-
tively pristine air quality even on days when they are not visiting the park.
Concern over preserving the Grand Canyon may be just as intense in New York
or Chicago as it is in nearby states and communities.
Thus, preservation value has two additive components, user value and
existence value. However, it is difficult to construct even a hypothetical
market to capture pure existence value. Rather one could imagine a lump sum
fee added., for example, to electric power bills to preserve air quality in the
Grand Canyon and the surrounding parklands. Such a hypothetical fee could
46
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capture total preservation value, the sum of existence plus user value, if
used as the basis of B survey questionnaire. In fact, the survey described
in the next chapter asked approximately one-third of the respondents a pure
user value question (how much would they be willing to pay in higher entrance
fees per day for visibility at the Grand Canyon or other parks) and the other
two-thirds of the respondents how much would they be willing to pay as
a higher monthly power bill to preserve visibility in the parklands, a total
preservation value question. Clearly, if total preservation value is much
larger than total user value, then existence values must be large.
From an economic-theoretical perspective, consumer preferences can be
modeled as follows:
Let CU = color contrast (visibility) during a visit to the site
by a user household;
C ¦ average color contrast over the year at the site;
V = number of visits per year by the household to the site;
D = distance of the household from the site;
m a cost per mile of travel;
Y = household income;
X = composite commodity;
q = quality of the visit,a function q(CU) of visibility during
the visit;
R = q v = quantity of recreation obtained at the site;
E = entrance fee per visit;
B = total lump sum preservation bid for visibility;
U 3 household utility, a quasi-concave increasing function
U(C,R,X,) of average yearly visibility, C, recreation at
the site, R, and consumption of the composite commodity, X.
In general, a household will wish to maximize utility,
U(C,R,X),
subject to the amount of retreation attained by visiting the site
R= q(CU)V
which we assume is the productof the quality of the visit, a function of visi-
bility during the visit, C"^ and the number of visits, V. Additionally where
we take the price of the composite commodity as unity, the availability of the
composite commodity is
X = Y - B - (E + 2mD)V
or income minus any lump sum bid for visibility, B, minus any expenditures
for visiting the site which are the sum of entrance fees, E, and travel costs,
47
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2mD, for each visit, V. Note, any costs other than travel costs could con-
ceptually be lumped with E. We take V, X, R, B, and E to be non-negative as
wel 1.
To get at user value, we will first take B to be identically equal to
zero. The first order condition for use, V, where we substitute the con-
straints into the utility function is then:
U_q - U (€ +• 2mD) ' 0
K X
Note that, with the terms rearranged, if
\ < E + 2mD
U q
x
then V = 0. In other words, if the sum of entrance fees plus travel costs
divided by quality (the r.h.s. above) exceeds the marginal rate of substitu-
tion between recreation and the composite commodity (the value of recreation
which is the l.h.s. above), then visitation is zero for the household. Note
then, that, where distance from the site, D, is large, V may well be zero,
a corner solution. Thus, someone from New York may never visit the Grand
Canyon and consequently have a zero user value as well. To show that user value
is zero if visitation is zero let us assume that the entrance fee, E, is a
function of visibility, *6 , sowe have E(CU). The consumer can then have a
first order condition over choice of C by paying E(C ). This condition is
V-(URq» - UxE') = 0.
If V > 0, the user will then have
x
So E' is a measure of marginal user value of visibility per visit. However,
i f V = 0, the first order condition for" C "is 'satisfied without equality of
URq' and U E', so E' measures nothing, i.e., is of no relevance to the consumer.
Tnus, logically, a change in entrance fees will measure marginal willingness
to pay for visibility in use only for users.
To get at total preservation value, let us fix entrance fees at E" and
allow households to make a lump sum bid, B, for visibility at the site where
we also assume that CU = C. In other words, households assume that the ex-
pected visibility level for their visit, C", is the average visibility level ,
c Since we have made the household utility function purely dependent on
visibility at the site, the marginal bid for better visibility (derived by
holding the utility level constant and totally differentiating the utility
function) takes the form
48
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Ma" "b I'
where the term in brackets "a" is the pure marginal existence value and the
term in brackets "b" is marginal user value per visit (shown to be E' above
for users if an entrance fee is collected for visibility). Thus, the lump sum
bid, B , "collects" both existence value and user value from the household. B
is then a measure of preservation value. The survey questionnaire presented
in the next chapter attempts to estimate both E^'^and B(C) as defined above
and thus provides measures of user and total preservation value.
The model developed in the paragraphs above focuses on the difference
between pure user value and pure existence value. The notion of pure existence
value was put forward by Krutilla (1 967) as an outgrowth of the notion of
option value developed by Weisbrod ( 1 964 ) . In particular, Weisbrod argued that
a potential user who might never actually visit a particular national park in
his lifetime might well be willing to pay to preserve the option of use over
that lifetime. This notion simply adjusts the concept of user value (as
developed in the model above) for uncertainty. In other words, a potential
user who might never make the trip to the Grand Canyon might be willing to pay
a kind of insurance premium to retain the option of future use. The notion of
pure existence value is, however, totally different from user or option value,
in that, knowledge of the continued existence of a pristine national park in
and of itself provides satisfaction. Thus, although option value might accrue
to individuals who might never visit the Grand Canyon, that value is still
based on potential use. Alternatively, existence value has no basis in actual
or potential use, rather only on knowledge of the continued preservation of
a unique resource such as the Grand Canyon.
ks
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REFERENCES
1. This approach does not account for uncertainty over visibility conditions,
but will suffice for our purposes here. A model incorporating uncertainty
would replace the user value notion with an option value measure.
50
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CHAPTER 6
SURVEY DESIGN
A. Introduction
The survey instrument addressed a multiple set of issues in the problem
of valuing visibility in the national parklands. First, the parklands are
unique national treasures and part of the national heritage. Thus, the
parklands and their characteristics (i.e., visibility) might be valued by all
citizens, whether or not they have or ever will visit the area. The survey
instrument elicited valuations for actual users--in the national parklands.
Second, new and current industrial facilities in the southwest impact not only
specific parks but potentially could contribute to a regional deterioration of
visibility. The survey instrument as a result of this local versus regional
deterioration problem addressed the valuation of visibility in the Grand Canyon
as well as in a regional scenic setting which included Mesa Verde and Zion National
Parks. Figure 12 depicts a regional map showing the relative location of the
three national parks, and their proximity to a partial list of existing and pro-
posed industrial facilities in the southwest.
The following subsection will consider general aspects of the overall
questionnaire design. Later subsections will address the actual mechanics of
the valuation questions. Appendix C includes the complete survey instrument.
B. Survey Instrument Structure
The survey instrument follows, in general, the design that is set forth by
Randall et al . (1974) and Brookshireet al. ( 1 9 7 6 ) . A hypothetical market is
established around a well defined nonmarketed good for the respondent and a
bidding vehicle is utilized. However, rather than a suggested initiation
point for the bidding process, a set of columns representing varying amounts
are given to the respondent enabling him to check the appropriate bid. This
alleviates the potential for starting point bias as described in Brookshire
etal. (1 976) and empirically observed in Rowe et al. (1980). No specific
mechanisms were incorporated into the questionnaire for other bias checks.
In general, biases have not been found to be a systematic problem in bidding
games. For a summary and analysis of bidding games in general and those ex-
ploring bias problems see Schulze et al. (1981).
Figure 13 presents the basic flow of information gathered by the survey
instrument. A brief introduction explaining the causes of poor visibility
and an explanation of the photographs of the Grand Canyon was presented to
each household. (See Chapter 2 for a complete discussion of the photographs.)
After the introduction, past and proposed future use by the household for the
Grand Canyon, Zion, Mesa Verde, Bryce, and Canyonlands National Parks was
51
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(H
m
Figure 12
REGIONAL MAP
UTA
ARIZONA
Slan
Canyon
an'al
R«cr*atiaa
Ar*a
Br ye*
Pag*
REGIONAL
Mt. Trumbul
wan*
Canyon
Flag Molt
INDUSTRIAL FACILITIES
V© Example list of Industrial Facilities
1. Navajo Power Plant, Page, AZ
2 San Juan Plant: Fruitland.NM
3. Four Corners: Farmington, NM
4. Copper smelters, throughout Arizoi
Planned
5. Intermountain Power Plant (Utah)
8. Garfield Power Plant (Utah)
7. Warner Power Plant (Utah)
Points of Interest
(7,1 78 ft.) Shiprock.NM
(7,178 ft.) Shiprock, NM - 35 miles
from Mesa Verde
(8,029 ft.) Trumbull Mountain, AZ - 50
miles from Zion and 1 mile
_ from Grand Canyon
Q
Ourongo
Farmington
Cortis
£W MEXICO
Gallup
52
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Figure 13
<.. , QUESTIONNAIRE STRUCTURE
Introduction
>
f
I Past and
Future
Use
/ \
| User Value Questions | I Preservation Value Questions |
i
Grand Canyon User Value Question
Socio-Economic/Demographic
Plume User Value Question
Regional User Value Question
Plume Preservation Value Question
Regional Preservation Value Question
Grand Canyon Preservation Value
Question
53
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determined. Households were asked how many days in the last ten years they
visited and how many days in the next ten Years they anticipate visiting the
above listed National Parks. Two-thirds of the respondents were given the
preservation value questions (i.e., user plus existence values), while one-
third were given the user value sequence of questions. Every respondent was
asked at the conclusion of the valuation questions a set of demographic/economic
questions: home zip code, education, age group, sex, size of household, whether
the respondent was primary income earner and income group.
¦4 •
The photograph sets utilized were presented to the respondents in a folding
display. All respondents were shown identical displays but the valuation pro-
cess was divided between user and preservation questions. In explaining the
photographs the following types of information were given to the respondent:
The Grand Canyon picture set displays a total of five levels of
visibility represented by Columns A through E and three vistas
from Hopi Point represented in the rows. Column A represents poor
visibility, B below average, C average visibility, D above average
and E good visibility. The rows in the picture display represent
morning and afternoon views from Hopi Point in the Grand Canyon.
The first row represents the different visibility and air quality
conditions looking east in the morning from Hopi Point. The second
row represents morning conditions looking west from Hopi Point. The
third row represents the view from Hopi Point in the afternoon
looking west.
The regional picture set display represents five different levels
of air quality from poor visibility, Column A, to good visibility,
Column E. The rows represent morning conditions for the Grand
'Canyon, Mesa Verde and Zion National Parks. Row 1 looks out from
Hopi Point towards the east in the morning at the Grand Canyon.
Row 2 represents the vista from Mesa Verde at Far View Overlook
towards the south in the morning. Finally, Row 3 is at Lava Point
in Zion National Park looking southeast in the morning.
The Grand Canyon and regional picture set displays were utilized for user
and preservation value questions.
The plume analysis picture display represents two situations.
In Picture A no plume can be seen looking west from Hopi Point
in the Grand Canyon. Picture B is identical except that a plume
is visible.
Again both user and preservation value respondents utilized the same plume
picture display.
Three other general character! sties of the questionnaire are worth men-
tioning. First, after all user and preservation value Grand Canyon and regional
bids were obtained, the respondent, if having bid zero, was asked the reason:
1) the air quality improvements represented in the columns were not significant,
2) the source of air pollution should be required to pay the costs of improving the
54
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air quality and 3) other (specify). Second, if the respondent stated
confusion as to the sources and causes of air pollution or to the veracity of
the photographs, a special verbal explanation was given to the respondent
explaining the sources and causes of air pollution in more technical detail.
This is presented as a supplement to the questionnaire in Appendix B. 11 .was
noted on the respondent's questionnaire if this information was requested.
Finally, all respondents were shown the map in Figure 12. This was to supplement
the picture sets and verbal description in describing the regional nature of
the visibility problem.
The areas sampled by the survey teams were chosen in a semi-random fashion
in that income class and racial composition were important factors in deter-
mining the sampled areas. Approximately one-third of the surveys were to be
taken from each of the following income classes; low, medium, and high. Also,
it was deemed desirable to obtain an appropriate mix of races representing the
average composition across America. Relying primarily on 1 970 census tract
data it was determined that several areas satisfied the income and race
considerations. Thus the actual areas sampled were chosen essentially at
random. The out-dated nature of the 1970 data made on-site inspection of the
selected areas necessary, but we found the redistribution over the last decade
to be minimal. Tables 10, 11 and 12 describe in detail the areas sampled and
provide some relevant census tract data. Actual data of the sampled population
is given elsewhere.
Before the interviewing commenced, a pre-test of the questionnaire was
carried out in Laramie, Wyoming. This served to identify problems in
the questionnaire and train the interviewing teams. Due to the size of the
picture displays and possible reluctance of some respondents to be interviewed
by males, male - female teams administered the surveys.
In any interviewing procedure, care must be taken that the process of
sampling and interviewing does not introduce biases into the responses. Thus
log sheets were kept by each interviewing team detailing whether a household
contacted was: 1) not at home, 2) wished to be interviewed later or 3) refused
to be interviewed. This allows the final survey results to be checked for
non-respondent bias and a type of sampling bias.
Let us turn now to a more detailed look at the content and sequence of
user and preservation value questions focusing on specific information given
the respondent and the mechanisms utilized for eliciting a response.
c. User Value Questions
The user value questions asked respondents' willingness to pay to
improve visibility in the Grand Canyon, willingness to pay to prevent a deteri-
oration of visibility from the current average for the Southwest region and
willingness to pay to prevent plume blight over the Grand Canyon.
The payment vehicle for the Grand Canyon user analysis was increments
in additional daily entrance fees. Respondents were told that all visitors
would end up paying the same total daily fee and further that all monies col-
lected would be used to finance the air quality improvements represented in the
55
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Table 10
Description of the areas sampled for the
National Park Survey Los Angeles County
Name of community
or area
Boundaries of the Census tract Hean Percent Percent
area sampled n umba ra income'' Blackc other races''
Santa Monica
West: Lincoln Blvd. 7022 11,924 1.6 5.2
North: Pico Blvd.
South: Ashland
East: 20th Street
Venice District
west: Washington Blvd. 2733 7913 38.9 2.1
North: Rose Ave.
South: Brooks Ave.
East: 6th Ave.
Venice District
west: Main Street 2736 9864 2.2 3.0
North: California Ave.
South : Venice Blvd.
East: Lincoln Blvd.
I ng I ewood
west
North
South
East
Rosewood Ave. 6012.02 11,353 .2 l.k
Arborvitae S t
Century Blvd.
La Brea Ave.
IngIewood
West
North
South
East
Wooster Ave. 7030 25,876 1.1 1.8
Slauson Ave.
62nd Street
: Char i ton Ave.
San Marino
West: Los Rabies Ave. 4641 34,992 .2 .6
North: Monterey Road
South : Huntington Dr.
East: Oak Knol 1 Ave.
Monrov i a
West: Myrtle Ave. 4303 13»513 -2 .7
North: Greystone Ave.
South: Lima Ave.
East: Shamrock Ave.
a. As defined in the maps of _BJiO£k_^tatjistjicsj__Los_^ni2e2eis_^_Liojiig_Bie££hJ_C£MfojwijaJ_Ujj3aj^^
T970 Census of Housing, U.S. Department of Commerce Bureau of the Census Publication HC(3) -18.
b. From Table P-4 "Income Characteristics of the Population: !$70" in Census Tracts: Los Angeles Long
Beach, California Standard Metropolitan Statistical Area: J970 C6nSUS Of Population and Housing, U.S.
Department of Commerce Publication PHC (1)- 1 1 7 .
C. From Table p-1 General Characteristics of the Population: 1970, ibid.
d. Calculated from Tibie p-i, :bid.
56
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Table 11
Description of the areas sampled for the
National Park Survey: Albuquerque Metropolitan area.
Name of community
or area
Boundaries of the Census tract Mean Percent Percent
area sampled numbePa income^ Slackc other races^
Albuquerque
'West: William Street 13 ^968 11.2 2.9
North: Stadium Blvd.
South: Woodward Road
East: i - 2 5
Albuquerque
'West: Rio Grande River 31 10,312 .k 2.3
North: Mon cano Road
South: Candalaria Road
East: San Isidrost. and
Guadalupe T .
Albuquerque
West: State Hwy. A48 24 7860 3.2 2.4
North: mterstate-40
South: Bridge Blvd.
East: Coors Blvd. , Central Ave.,
and Rio Grande River
Albuquerque
west: 8th St. and 5th St. 28 5919 7.9 4.7
North: interstate-40
South: Lotnas Blvd.
East: Broadway N.E.
Albuquerque
West: i nt e r s t at e-2 5 16 7161 2.0 5.0
North: Grand Ave.
South: Haze Id i ve Ave.
East: University Blvd.
Albuquerque
West: Carlisle Blvd. 5 1 0,833 .3 2.2
North: Lomas Blvd.
South: Zun i Road
East: San Pedro Dr.
Albuquerque
West: Carlisle Blvd. 2.01 12,25
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Table 12
Description of the areas sampled for the
National Park Survey: The Denver Metropolitan area.
v-n
CO
Name of community
or area
Boundaries of the Census tract Mean Percent Percent
area sampled number5 income'3 Black1 other races''
Denver
East: York Blvd. 23 6582 83.1 1 .7
South : 23rd Street
North: 32nd Street
West: Downing Ave.
Denver
East: Platte River 6 6547 .3 2.7
South: 19th Street
North: Speer Blvd.
West: Federal Ave.
Denver
East: (1-25) Valley 40.03 12,365 ,3 .7
South: Hampden
North: Yale
West: Colorado Blvd.
Denver
East: Colorado Blvd. 39.01 25,892 .1 .4
South : Mississippi Blvd.
North: Alameda Blvd.
West: University Blvd.
a. As defined in the maps of, Census Tracts Denver, Colorado Standard Metropolitan Statistical Area: I 970
Census of Population and Housing, JIT Department of Commerce Bureau of the Census Publication PHC(1)~56.
b. From Table P-4 "Income Characteristics of the Population: 1970," ibid.
c. From Table P-1 "General Characteristics of the Population: 1970," ibid.
d. Calculated from Table P-1, ibid.
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pictures. After explaining the air quality problem in the Southwest region
(verbally and via pictures), the payment vehicle, and stating the mean payment
criteria, the respondent was asked to bid always comparing the proposed improved
air quality (i.e., Columns B or C or D or E) with the lowest air quality condi-
tions as represented in Column A on the picture display. Further, the respon-
dent was asked to assume, when bidding, that each photograph represented the
visibility on a day that he would be visiting the Grand Canyon National Park.
An example portion of the question presented to the respondent is:
This is Column A, representing very poor air quality and
visibility. Please indicate on your answer sheet how
much of an increase above the total daily park fees of
$2.00 per car load you would be willing to pay for your
household to improve the visibility to that shown in
Column B. Put a B next to the highest dollar amount you
would pay per day if you were visiting in question E5 on
your answer sheet.
While the bidding for Column B versus Column A was being conducted, all
other columns were covered up. The process continued for Column A versus
Column C etc., again the remaining unused columns were covered.
The regional user value questions varied only slightly from that of
the user value questions for the Grand Canyon. First, the picture set was
described earlier; second, entrance fees would be raised not just in the Grand
Canyon but throughout the national parklands in the Southwest. Finally, the
following additional information was provided:
If current emission standards are maintained, the
average conditions will be as seen in Column C. If,
however, current emission standards on existing and pro-
posed industrial facilities are relaxed or not enforced,
then average air quality and visibility in the region
will be represented as in Column B. As shown in Column
B a deterioration in visibility would occur in the Grand
Canyon, Zion and Mesa Verde National Parks. As a result,
conditions as presented in Columns C, D, and E will
occur less frequently. Conditions in Columns A and B
would occur more frequently. We would like to know how
much the maintenance of average regional air quality and
visibility is worth to you.
The bidding question presented to the respondents was then for pre-
venting a deterioration from the conditions represented in Column C to con-
ditions in Column B and thus shifting the frequency of occurence of all
conditions to a generally poorer level of visibility in the region. The
valuation question was as follows:
How much would you be willing to pay per day in addition
to existing park entrance fees for your household at the
Grand Canyon, Mesa Verde, or Zion National Parks to prevent
a deterioration in visibility in the region as represented
59
-------
in moving from Column C to Column B. [SHOW photographs and
POINT TO COLUMNS C AND B FOR GRAND CANYON, MESA VERDE AND
ZION]. Assume that entrance fees would be raised throughout
the National Parks in the Southwest. Please put an R next
to the dollar amount closest to the highest increase in
daily entrance fees you would be willing to pay for your
household for a region-wide preservation in visibility for
question E6.
Finally, the plume analysis addressed visibility problems other than
regional haze. The pictures utilized were discussed earlier. Again the bid
was in terms of daily entrance fees for the prevention of plume blight while
visiting the Grand Canyon.
D. Preservation Value Analysis
The preservation value analysis varied only slightly from the user
analysis. First, the vehicle was an increase in monthly electric utility
bills. As in the user regional analysis the focus was on the possibility of a
shift in the frequency of occurrence of the various visibility conditions
represented by Columns A through E. In particular the following information
set the background for the bid:
Again, let us look at the photographs representing visual
air quality ranging from very poor in Column A to very
good in Column E for east and west views in the morning
and afternoon from Hopi Point. If current emission stan-
dards are maintained the average conditions will be as
seen in Column C. If, however, the current emission
standards for sulfur oxide are not enforced, then average
air quality and visibility in the region will become like
Column B. As a result, conditions as represented in
Columns C, D and E will occur less frequently. Conditions
in Columns A and B would occur more frequently in the
Grand Canyon. Such emission controls will likely make
electricity more expensive.
The specific bidding question given to the respondents was as follows:
We would like to know if you would be willing to pay
higher electric utility bills if the extra money collected
would be used for additional air pollution controls to
preserve cu-rrent air quality and visibility levels at the
Grand Canyon. How much extra would you be willing to pay
at most, per month as an increase in your electric utility
bill to preserve current average visibility as represented
in Column C rather than have the average deteriorate to
that shown in Column B? Please put an X next to the
highest amount you would be willing to pay per month for
your household on your answer sheet for question E8 .
60
-------
The regional preservation value question also used electric utility
bills as the bidding vehicle, focused on a shift in the frequency of occurrence
from the current average in Column C to that in Column B and utilized the
regional picture set board discussed earlier.
A difference, however, between the structure of the regional user and
preservation value questions does exist. Recall that the regional user question
was a separate b i d from that for preserving visibility just in the Grand
Canyon. The preservation regional question was a willingness to pay question
that asked how much more above and beyond the amount the respondent stated
when only bidding for visibility in the Grand Canyon.
Finally, the preservation value plume blight question mirrored that of
the user question except that the vehicle was increases in electric utility
bills. Again, this was for preserving, thus preventing plume blight over the
Grand Canyon.
61
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CHAPTER 7
, . SURVEY RESULTS
A. Introduction
In this chapter the results of the survey efforts described in Chapter
6 are presented and analyzed. Two groups of responses are analyzed. Survey
participants who answered questions concerning their willingness to pay
an entrance fee to the Grand Canyon National Park are called "user value
respondents." Those who were asked questions concerning their willingness
to pay higher electric utility bills to preserve or improve air quality
in the Grand Canyon National Park and the surrounding region are referred
to as "preservation value respondents."
Section B contains a discussion of various socio-economic and demographic
characteristics of the survey respondents. Section C presents a detailed
report of the findings of the user value component of the survey. The pre-
servation value findings are then presented in Section D.
B. Socio-economic and Demographic Characteristics of the Sample
There exists in each of the survey subsamples a substantial similarity
in gross demographic measures. These are presented in Tables 13a and 13b.
In both cases the Los Angeles and Denver groups are quite close in mean
years of formal education, age and income while the Albuquerque group
was on average younger, less well educated and received substantially
lower incomes. The Chicago group consisted exclusively of preser-
vation value respondents and within this category occupied intermediate
positions in education and income. The Chicago respondents' mean age was
slightly higher than that of any other city.
Within each city, the user value respondents tended to be younger,
better educated and the recipients of higher incomes than the preservation
value respondents. Visitation experience and plans of these respondents is
reported in Figure 14. An exception to this tendency is that in Denver user
value respondents reported a mean income slightly less than did existence
value respondents. The difference, though, is sufficiently small that it
warrants little discussion given the broad similarities observed.
All these measures, then, bear relationships to one another which enhance
their prima facie plausibility as the results of a representative survey of
United States citizens. The household size and electricity bills reported
similarly tend to confirm that an appropriate sample was selected.
62
-------
Table 13a
Socioeconomic characteristics of existence value
respondents by city (mean and standard deviation)
Number of
Respondents
Education
(years)
Age
(years)
HousehoId size
(number of
members)
Income
(x $1000)
Elect. Bill
(do Ilars/month)
Albuquerque
115
13.60
(2.57)
38.6o
(14.47)
3.23
(1.79)
19.02
(11.61)
36.78
(22.99)
Los Angeles
127
14.52
(2.21)
41.05
(14.89)
2.72
(1.70)
28.06
(20.40)
3 6.27
(25.79)
Denver
110
14.76
(2.34)
40.84
(14.61)
2.54
(KM)
30.57
(20.64)
58.41
(39.79)
Ch i cago
98
13.91
(2.39)
42.66
(14.62)
3.8o
(1.97)
25.93
(18.25)
55.64
(40.65)
Table 13b
Socioeconomic characteristics of user value
respondent by city (mean and standard deviation)
Number of
Respondents
Education
(years)
Age
(years)
Household size
(number of
members)
Income
(x $1000)
EIect. Bill
(do Ilars/month)
Albuquerque
61
14.26
(2.29)
35.31
(14.15)
2.88
(1.52)
25.29
(15.90)
36.02
(17.24)
Los Angeles
60
14.90
(2.37)
36.60
(13.06)
2.98
(1.35)
30.77
(20.59)
42.53
(32.68)
Denver
45
15-02
(2.47)
37.11
(15.36)
3.09
(1.67)
30.14
(15.89)
47.67
(26.32)
-------
Figure 14
Grand Canyon Visitation
Experience and Expectations of User
Value Respondents,by city.
30°fo
20° b
07
-------
c. Value in Use to Visitors
The user value survey participants were asked to reveal the maximum
additional amount over the current $2.00daily fee they would be willing to
pay for daily admission to Grand Canyon National Park if this fee would be
used to maintain specified degrees of air quality. The question was phrased
as to ask the maximum total daily fee to maintain each of conditions B, C, D
and E over condition A, a situation with severely impaired visibility.
4 • •-*
The mean and standard deviation of responses in each city are presented
in Figures 15a, 15b and 15c. A notable feature of these results is the uni-
form display of what might be called increasing returns to scale in air quality.
In all three cities nearly half of the total bid for very high visibility was
an increase over only slightly diminished clarity. This seems to contradict
the conventional assertion that incremental improvements in air quality
would yield ever smaller benefits to viewers.
Instead, m^re serious thought must be given to what has been called the
Dubos Hypothesis. This argument holds that for "natural wonders" it is in
fact the pristine state that is valued, and that once any degradation has
taken place additional damage matters relatively little. The bids for air
quality preservation at the Grand Canyon certainly appear to be consistent
with this hypothesis, as does the decline in zero bids for greater improvements
in air quality. (Tables 14a and Hb present this information.) Were "not
significant" not the most frequently given reason for zero bids for the visi-
bility change one would regard this as unremarkable, but the fact that the
initial improvements are regarded as insignificant by most zero bidders is in
itself noteworthy.
The visitation experience of user value respondents for the Grand Canyon
is consistent across income groups and city of residence. Tables 15a and
15b present mean visitation during the previous ten years by city and income
class respectively. One interesting aspect is that less than one day per ten
years separates the Los Angeles group (with the highest mean visitation) from
Denver (with the lowest) as is the similarity of visitation experience among
low, middle and high income groups.
As might be expected, use of other National Parks in the region varies
considerably among cities and income as well as among the parks themselves.
One suspects that a visit to Grand Canyon National Park is the central feature
of most parklands tours with trips to other parks and national monuments
reflecting any number of family characteristics such as length of vacation,
later destinations and knowledge of the region.
Visual quality in these other areas is apparently less valuable to users
than at the Grand Canyon. Figure 16a presents the mean bid of respondents to
avoid a regional decrease in average air quality from C to B. The mean regional
bid in Albuquerque was $.99 more than the comparable Grand Canyon bid, while
in Los Angeles and Denver the increases were $1.24 and $2.40 respectively.
Only among Denver respondents did the surrounding region rival the Grand
Canyon as a source of viewing pleasure. This might be a result of Denver
residents' relatively heavy use of other parklands parks as presented in Table
15a.
65
-------
Figure 15
Mean Bid for Specified Visibility Conditions
at Grand Canyon of User Value Respondents,
by City (with standard deviation).
Bid ($)
(a) ALBUQUERQUE
5.38
(4.51)
1.46
L (1.45)
'mmmw
2.19
(1.88)
Visibility Conditions
B
Bid ($)
10
9
8
7
6
5
4
3
2
C D
(b) LOS ANGELES
4.81
(4.05)
3.53
(2.28)
2.05
(1.63)
Visibility
AMAVAVAVMMVAMWM
VAVAVAVVVWAV
vavavavavav;
M ~~~~~~ ~>.~~~~»~»<
AVAVAWAVAV
~VAVAVA AV»tt ~ i
AVAVAVAWAW
>v»v v v'vMC* AVAVAVA ~ ~ ~»
mVAVAVAW AVAVAVVAVAVA
MMtMM
wavavAVAVAVAV^
AVAVAVAWAW
/~vmv»vm»>yhy>> AVAVAVA ~ ~ ~»
mVAVAVm AVAVAVAVAV/A
~ ~> MM~ 'AVAVAVAVAVVV vavavavavavv
Visibility Conditions
Bid ($)
(c) DENVER
6.33
(8.63)
2.53
(3.39)
3.79
(4.97)
1.49 .
(I. 84)
mmm
MA MA MAMA* AMA«
B
~ ~~~~~~~*~~~•~~~~ AVAVAVAVAVAV
AAVAAAAAVVavAVVAVVVVAVA
*4 4 * 4 4**44*******~~~~~~~~~~»~~~~~~
* AV AVAV AVA>VA V A A\V AVAV AVV v//~ v.VAVAV AV
AVAVAVAVAVAV VVVVVVVVVVVVVVVVV vv^
1 lYitmittiliLiUiiutiiiiiiinuit 'Httntmnttm
standard deviation in parentheses
Sample size (number of households) for Albuquerque,
Los Angeles and Denver is respectively, 61, 60 and 45.
Visibility Conditions
66
-------
Tab Ie Ha
Zero bids by user value respondents for
specified visibi I ity improvements, by city
(number of zero bids)
A^fl A-+C A-*0 A->€
Albuquerque
Los Angeles
Denver
10 6 4 2
2 1 I I
12 8 6 4
Tab I e >1*6
Zero bids by reason among user val w respondents
source shou Id
not significant Dav other total
Albuquerque
Los Ange les
Denver
9 2 I 12
I 023
3 2 2 7
1
Table 15a
Southwest Nat ional Park us* patterns (by city)
for user value respondents. (Number of days
at parks during previous ten years; mean and
standard deviation. )
Grand Canyon
Zion
Mesa Verde
Bryce
Others
A 1 buquerque
2.69
.47
1.73
.52
2.08
(3.60)
(I. 06)
(3.67)
(1.35)
(3.91)
Los Angeles
3.28
1.77
1.35
1.65
3.20
(5.67)
(4.05)
(*-21
(4. 30)
(5.99)
Denver
2.51
.80
2.24
1.29
6.27
(2.82)
(1.44)
(3.66)
(2.36)
(7.78)
Tab I e 15b
Use patterns among user value respondents by i ncome c I asses
(Mean days in previous ten years)
G raod Can yon
Zion
Br yce
Mesa Verde
Low I ncome
(14,999 or less)
2.85
.78
.68
2.05
Middle Income
(15,000 - 19,999)
2.98
1.26
I. *7
1.33
High 1ncome
(20,000 or more)
2.73
.97
1.11
1.92
67
-------
Figure 16
Mean regional and plume avoidance bid
by user value respondents, by city
(a) Regional Bid
(b) Plume Avoidance Bid
Bid ($)
Bid ($)
^.77
(7.60)
4.93
(14.83)
3.16
(3.55)
mm
«tum<
* *-£W
It fit
I f
mtfit
Hil
mmmm
v
v°'
4.80
(6.98)
5.57
3.18
(3.26)
llMfCf
V/rWf
VAVhVAV«V
Ct tU
'f mt
rWAWWAV.
ItHK ft
ntH (ft
w'VAVAVA'/*
W.V.WAW
# t r.* ».»*
»t>if«»~»
niimc
City
68
-------
Denver user value respondents were also exceptional in their valuation
of plume blight. When asked to reveal the highest daily use fee they would
pay to avoid the presence of conspicuous Plume on the horizon, Albuquerque and
Los Angeles respondents offered a bid that averaged very close to the bid for
the maintenance of slight haze (situation D). In Denver the mean plume avoid-
ance bid was substantially higher than the bid for situation D. The plume
avoidance bids are depicted in Figure 16b.
D. Preservation Value .,
Preservation value respondents in each of the four cities were asked how
much they would be willing to pay as an increase in electric utility bills to
prevent average visibility declining from situation C to B.
While preservation value respondents were asked their visitation plans
and experience, no use was made of this information in the survey except that
respondents who had neither visited nor planned to visit the Grand Canyon were
forced into the preservation value group. Even so, a substantial portion of
the preservation value respondents in each city had visited the Grand Canyon
and a majority planned to visit. Figure 17 presents visitation experience and
plans for preservation value respondents in each city.
In Table 16 the mean number of days spent at various southwestern national
parks can be seen. No data is offered for the Chicago respondents since they
were asked simply whether they had visited Grand Canyon and whether they
planned such a trip. Among the respondents in the other cities the pattern is
much the same as for user value respondents except that the numbers are smaller,
as would be expected. Mean days of visitation at the Grand Canyon is approx-
imately the same in each city and Denver respondents had used "other" parks in
the region much more than did residents of Albuquerque and Los Angeles.
The bids of preservation value respondents, it must be remembered,
include both a user value and a pure existence value and thus would be expected
to exceed a comparable user value bid. The bids used in the user and pre-
servation value variants of the survey described here are sufficiently distinct
that some discussion seems appropriate.
The user value bids, it will be recalled, are formulated as daily
increases in entrance fees during a visit that is anticipated. The preserva-
tion value bids are to be paid whether or not the respondent actually uses
the Grand Canyon or surrounding parklands region. A user value bid comparable
to preservation value bids reported would be, then, the product of the daily
bid and average number of days per month the fee will be paid. Whether one
uses actual visitations in the past or declared intentions, the user value
will be insignificant compared to the preservation value bids reported in
Table 17. The Grand Canyon bids in this table are for the maintenance of
situation C as the average visibility condition. If the same relationships
held among preservation values for visibility as among user values, an increase
in visibility to situation E would more than double these bids. One hesitates
to assert that such is the case, but the consistency with which the Dubos
Effect was observed among user value bids requires at least a mention of this
possibility.
69
-------
Figure 17
~
Grand Canvon visitation experience and ejections
of preservation value respondents.
Plan to visit in future
Have visited in past
70.7
74.2
38.3
28.3
71.9
3I.6
53.8
MM
Albuquerque
Los Angeles Denver
Chicago
70
-------
Table 16
Southwest National Park use patterns (by city)
for preservation value respondents. (Number
of days at parks during previous ten years;
mean and standard deviation. )
Grand Canyon
Zion
Mesa Verde
Bryce
Others
Albuquerque
1.38
.35
.67
.28
1.79
(3.25)
(l-93)
(1.58)'
(1.15)
(4.72)
Los Angeles
1.17
.83
.45
.68
1.65
(3.06)
(1.90)
(1.58)
(1.72)
(4.40)
Denver
1.11
.26
1.50
.21
4.25
(2.62)
(.69)
(2.^7)
(.54)
(6.40)
Table 17
Preservation value bids by city; mean and standard deviation ($)
Grand Canyon
Additional
for
Region
Plume
Avoidance
Albuquerque
4.09
4.14
4.25
(11.68)
(14.41)
(13.42)
Los Angeles
5.14
4.50
2.84
(10.79)
(10.32)
(4.53)
Denver
3-72
2.89
2.89
(5-3D
(4.12)
(4.54)
Chicago
9.06
7.10
k. 32
(30.49)
(24.80)
(13.77)
71
-------
The preservation value of clean air in the region appears to be sub-
stantial to residents of all four cities surveyed, as does the avoidance of
plumes. The regional bids presented in Table 17 are bids in addition to the
Grand Canyon bid. In an important sense, the plume avoidance bid is also an
additional bid since it addresses a separate issue.
The magnitude of these bids when compared to user value bids, especially
given the large portion of the respondents who reported an intention to visit
the Parklands region," might cause some concern regarding the true apportion-
ment of user option value and pure existence value.
In Fig ures 18-20 mean bids are presented for respondents by city and by
visitation experience and plans. These partitions of the sample suggest that
visitation plans are not an overwhelming factor in determining bids and that
knowledge acquired through past visits is also of relatively little importance.
Among Albuquerque participants previous or planned travel to the Grand
Canyon is associated with larger bid differences than for any of the other
cities. This may be a result of Albuquerque's proximity to the Grand Canyon.
That is, those who find such things attractive intend to visit the Grand
Canyon. The 25.8% of the Albuquerque sample that has no plans to visit the
Grand Canyon has the lowest average bid in every classification. A Grand
Canyon experience makes much less difference in the mean bid.
For both Grand Canyon and Parklands total bids the mean bid among Los
Angeles respondents was higher without experience or intention to see the
Grand Canyon, while visitation plans resulted in higher plume avoidance bids
and visitation experience in lower bids. This would seem to suggest a sub-
stantial pure existence value.
Past exposure to the Grand Canyon made very little difference in mean
Grand Canyon or regional bids in the Denver sample, while anticipated Grand
Canyon travel made a large difference in both these measures. The same was
true of plume avoidance bids, with travel plans being associated with sub-
stantially higher bids.
The Chicago group had the highest mean bid in every category and with
only one exception past or planned visits to the Grand Canyon resulted in a
lower mean bid., The exception is the Grand Canyon specific bid in which
respondents planning a visit made average bids slightly higher than did those
not planning a trip to the Grand Canyon.
One would have expected bids to decline with distance, and the substan-
tial margin by which the Chicago bids were higher remains a topic of interest.
In the next chapter it will be seen that even when adjustments are made for
the income and age of respondents, distance has little discernible effect on
bids to preserve air quality in the Grand Canyon.
72
-------
Figure 18
Mean Grand Canyon Bids of preservation value respondents,
by city and past and future visitation
Have not visited in past
pTtTu*
[MVijmj Have visited in past
(a) Past visitation
5.67
( 12.26)
5.34
(16.42
3.79
5.49
ULOJWA*
v.mv
3.56
(5.40)
4.15
(5.20)
mrnt
VAV.V.V
V.V.W.V
:vHv:
mm
5.33
13.77)
4.31
(9.07)
m
* i* ~t>»*
M M f tt t
Albuquerque
.OS Angeles
Denver
Chicago
.City
6,30
(19.36)
(b) Future visitation
5.56
5.17 (11.46)
5.08
(13.59)
4.82
(7.02)
4.15
(4.89)
ill*'
HUtlit
lUMt'
m Aim
***<»(•)
IK*
M UM it
»
¦ ntt
HII
Albuquerque
_os Angeles
Denver
Chicago
City
Do not plan to visit in future
m IVtV Plan to visit in future
lli
standard deviation in parentheses
73
-------
Figure 19
Mean total regional bids of preservation value respondents,
by city and past and future visitation
Have not
visited
in
past
VV&u Have visited in past
11.69
36.03) ^ oq
•10.28
22.28)
»~~~~»»•(
8.01
(11.86)
(14.98)
(a) Past visitation
10.30
(24.95)
6 53 697
mm
mm
VAV.7A
few
9.97
(27.03)
Albuquerque
Los Angeles
Denver
Chicago
Citv
Bid
$ 13
12
[
10.37
(29.76)
n
12.57
58.82)
(b) Future visitation
8.84
(11.42)
nitiiiii
t '£ i M M k K A A
tl
yfimrr
f/AVtV
i
vSw'AV
i®
i'AYAV»
»~~~~~~~~
11
4.II
(9.02)
7.68
(8.45)
immii
~ H «ll.t
VAVAVi
~»»»»«••
•wXv:
m
-WAWi
A A .
A'AYAV
AVAYA,
AWAW
iiiiiiii
II.46
(30.66)
1
10.13
(21.59)
Albuquerque Los Angeles Denver
Do not plan to visit in future
City
Chicago
Plan to visit in future
'standard deviations in parentheses
74
-------
Figure 20
Bid
Mean plume avoidance bids of preservation value respondents,
by city and past and future visitation
Have not visited in past
Have visited in past
5,34
(I6.65J
3.58
(11.04)(
if1111111
IIHII »,*
U «it * t»
(a) Past visitation
4.71
(I 5.20)
3.05v
(4.48)
n
2.30
293
(4 90) (3/78)
1
2.41
Albuquerque Los Angeles
(b) Future visitation
5.61
(15.59)
Denver
Chicago
6.87
(20.0«
City
3.32
4.59
4.89
m.%
K11 « «
I a tt. t a
(5.35)
rrrmrr;
Utllfttt
uYiAYt
68
(2.51)
4.37)
m «<
mu
M4*
(Milt
mum*
m t w
ti"UM
ItMMM
Miiin
Albuquerque
Los Angeles
Denver
Chicago
City
~
Do not plan to visit in future
Plan to visit in future
standard deviations in parentheses
75
-------
REFERENCES
1. See Chapter 6 fof a discussion of the survey procedures used and the
modifications adopted for the Chicago sample.
2. The name is taken from Rene Dubos who proposed that as the environment
deteriorates people care less and less about further deterioration. In
other words, people put a special value on pristine environmental
conditions.
76
-------
CHAPTER 8
AGGREGATE BENEFITS OF PRESERVING VISIBILITY
A. Introduction
This chapter will present aggregate benefit estimates for preserving
visibility in the Grand Canyon and the southwest region as a whole. As
discussed, the survey enabled revelation of the household's willingness to pay
for preserving and/or improving visibility in specific parks of the Grand
Canyon Region. Recall the bids stated by respondents in the preservation
value section of the survey encompass both pure existence value and user's
valuation of preserving visibility. Therefore, to estimate the visibility
preservation benefits, it suffices to concentrate on and work with the preser-
vation value section of the survey.
The benefits in question can be estimated by applying statistical tech-
niques to the results of the survey conducted for this study. It can be
hypothesized that the amount of the bids offered by interviewees to preserve
and/or improve visibility in the areas where the survey focused is a function
of certain relevant independent variables such as income, age, race and
distance from a national park. Utilizing such a relationship we can estimate
the benefits to residents of the southwest region as well as the entire nation
resulting from the preservation of visibility in the Grand Canyon National
Park and Parklands Region."
B. Estimating the Benefit Function for the Southwest
In estimating an individual mean dollar benefit function, certain char-
acteristics of the sample population should be considered in that the cities
of Los Angeles, Albuquerque, Denver and Chicago are not homogeneous. That is, in
order to aggregate across all populations the demographic and economic profile
of each city must be considered. Thus we hypothesize that a household bid is
a function of family income, age of the family head, race, the household's dis-
tance from a national park and an error term.
To estimate the benefits to residents of the Southwestern U.S. (con-
sisting of the following states: California, Colorado, Arizona, Utah, Nevada,
and New Mexico) of preserving visibility in national parks three benefit
functions have been estimated utilizing the Albuquerque, Denver, and Los
Angeles data. Table 18 summarizes the estimated benefit functions. A brief
analysis of the results follows.
77
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Table 18
Benefit Functions Estimated from
Albuquerque, Denver, and Los Angeles Data
Bid for
Preserv i ng
Visibility ($)
Constant
1ncome
[$1000)
Age
(years)
Race
(wh i te » i)
(nonwhite - 0)
D i stance
(mi les)
*2
Number
of
Observat ions
Grand Canyon
9.19 ,
Ct.23) «
.05
.(1.79)
-.14
(-4.01)
2.03
(1.69)
-.0037
(-1.2)
.06
352
Reg i on
(Grand Canyon,
Mesa Verde and
Zion)
18.11
<4.ll)
.103
(1.79)
-.26
(-3.7)
3.69
(1.52)
-.0088
(-1.46)
.05
352
Plums Blight
over the Grand
Canyon
8.67
<*. SM
.0014
(.06)
-.12
(-4.02)
1.03
(.97)
-.0021
(-.81)
.05
352
at-statistics in parentheses
As Table 18 indicates, the relationship between income, age,, race, distance
and the amount of bid-offered is as expected. Higher levels of income should,
normally, raise the amount of bid offered. Age contributes in a negative
manner in all bid equations implying the young are seemingly more concerned
with air quality problems in" the area. Since "whites," on average, fall
in the "higher brackets" of income and education distribution in the United
States compared to "nonwhites," it is reasonable to expect higher bids from
whites than nonwhites. In addition, it is likely that "race" captures other
social and cultural characteristics which are not easily observable. The rela-
tively low t-statistic possibly reflects a substantial diversity within each
of the "white" and "nonwhite" groups. The negative relationship between dis-
tance and the amount of bid offered indicates that the greater the distance
from the national parks, the less their overall bid, However, the relationship
between distance and the amount of bid offered is not strongly significant.
Furthermore, as it will be seen shortly this result does not appear consistently
in all of the analysis. Note also that the coefficient of determination (R )
in all three benefit equations reported in Table 18 is extremely low. This
indicates that there may be other important independent variables that affect
the bidding behavior of the households, but which have not been accounted for
in this study.
Nevertheless, it is possible to estimate the aggregate benefits accruing
to the Southwest region of the United States from preserving visibility in the
Grand Canyon National Park area. Let us first consider the benefit equation
for the Grand Canyon (Row 1, Table 18). This equation indicates that if the
average family income, average age of the head of households, ratio of white
and nonwhites and the distance to the Grand Canyon from a particular state,
say Arizona, is substituted in the equation, then the amount of bid an average
household in Arizona would offer to preserve the visibility in the Grand
Canyon would be estimated. Then if the benefit measure so estimated is multi-
plied by the number of households in the state of Arizona, the total amount of
money that the entire population of Arizona would be willing to pay to preserve
visibility in the Grand Canyon National Park is estimated. Following a similar
78
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procedure, it is possible to est mate the aggregate benefits for the remaining
five states in the Southwest r^g on, and hence, the aggregate benefits to the
Southwest region is estimated.
Table 19 indicates, the aggregate benefits for the Southwestern region
from preserving visibility in the Grand Canyon National Park, the encompassing
region (Grand Canyon, Mesa Verde, and Zion) and for avoiding plume blight over
the Grand Canyon is respectively $466 million, $889 million, and $373 rnil 1 T on.
Table 19
Annual Aggregate Benefits for the
Southwest Region
Benefits for Preserving Visibi I i ty
in the:
total ($ Millions)
Grand Canyon
466
The Regiona-
Grand Canyon, Mesa
Verde and Zion
National Parks
889
t Avoidance of Plume Blight
373
aBenefits for the region include benefits for the Grand Canyon
c. Estimating Benefit Functions for the Nation
To estimate the aggregate national benefits from preserving visibility
in the Grand Canyon National Park, surrounding region and for avoidance of
plume blight, benefit functions in Table 20 are re-estimated, utilizing
the interview data from Albuquerque, Denver, Los Angeles, and Chicago. Thus
the principal difference will be the influence of the bids obtained from
respondents in Chicago. Table 20 summarizes the re-estimated benefit func-
tions which will be used to estimate the aggregate national benefits of pre-
serving visibility.
Table 20
Benefi t Functions Estimated from Albuquerque
Denver, Los Angeles, and Chicago Data
Bid for
Preserv i ng
Visibility <%)
Constant
1 ncoflie
($1000)
Age
(years)
Race
(white ¦ 1)
(nonwhite ¦ 0)
01 stance
(mi les)
K2
Number
of
Observat ions
Grand Canyon
8.36
(4.76)
• 0l<7
(1.76)
-.15
(-4.59)
1. H
(1.02)
• 000
-------
The benefit functions reported in Table 20 are for the most part
similar to, and consistent with, the benefit equations obtained from the sub-
sample of the Albuquerque, Denver, Los Angeles interviews reported in Table
18. Examination of Tables 18 and 20 reveal that the degree of signifi-
cance of income is consistent in both sets of equations. Note that the
significance of income in the "plume" benefit equation is lower than the
other two equations in both Tables. Age remains strongly significant and
consistent in the two sets of equations. The behavior of the variable "white/
nonwhite" is very similar to that of the income. The direction of the rela-
tionship is consistent; so is the degree of significance among the benefit
equations of each table as well as between the two tables. The only major
difference is the relationship between distance and the amount of bid offered
when the Chicago interviews are not included (Table 18) and included (Table
20) . The direction of the relationship reverses itself from negative to
positive when the Chicago data is added to the sample (except for the "plume"
equation) . Furthermore, significance level for the distance variable fails to
be consistent. Without the Chicago data, distance is relatively more signifi-
cant (except in the "plume's" benefit equation); after the Chicago data is
added, the direction of relationship of this variable changes and it also
fails to be significantly related to the amount of bid. Nevertheless, it is
convincing to note that other than for the distance variable, when the sample
size is increased by some 21%, (as Chicago data is added to the sample), the
relationships remain consistent and stable.
The aggregate national benefit estimation procedure is identical with the
procedure employed in the previous pages to estimate the benefits to the
Southwest region. Aggregate benefits to all states (except Alaska and Hawaii,
but with the addition of the District of Columbia) have been summed to arrive
at the national aggregate benefits from preserving visibility. Table 21
summarizes the aggregate national benefits.
The benefits of preserving visibility for the Southwest and the Nation
can be related to emissions by noting the following. Projected emissions
with currently planned levels of SO^controls would not produce a perceivable
decline in visibility in 1990 accoring to the calculations from Chapter 3.
However, complete decontrol of projected regional power plant emissions of
S02in 1990 would decrease visibility by approximately the same amount as
shown in the photographs which form the basis of these benefit estimates.
Thus, one can interpret the aggregate bids to preserve regional visibility as
the projected benefits of power plant S02controls in 1990.
The annual figures presented in Tables 19 and 21 represent benefits to
the Southwest and tine nation for preservation of visibility in 1980. In order
to obtain benefit estimates for 1990 power plant controls two modifications
are required. First, the benefit figures are adjusted by the expected popula-
tion growth over the next decade. Bureau of Census estimates "
tion growth of approximately one percent per year is expected. ~ ilV4a"
present value of future benefits must be calculated. Assuming a thirty year
life span for power generating plants and real rates of discount of 3, 6, and
9 percent, Table 22 summarizes the present discounted value of future benefits
in constant 1980 dollars to the Southwest region and the entire nation from
preserving visibility in the Grand Canyon National Park and the Parklands region.
80
-------
Table 21
Annual Aggregate National Benefits from Preserving
Visibility in the Grand Canyon National Park
Benefits from
TOTAL ($ Millions)
The Grand Canyon
3,370
The Region - Grand
Canyon, Mesa Verde,
and Zion
5,760
Avoidance of Plume over
the Grand Canyon
2,040
The nine percent real discount rate case corresponds to a ten percent
discount rate and a continued one percent growth in population. This case is
therefore consistent with the Office of Management and Budget discount rate
guidelines (10 percent) for assessment of future benefits. Thus, the nine
percent case seems the most apropos for comparison to the associated pollution
controI costs.
The comparison between benefits and costs can either be completed i n
present value or annual terms. Usuing the latter method requires annua I ization
of the present value figures reported in Table 22. Focusing on the nine percent
discount rate case and using a capital recovery factor based on a ten percent
rate of interest the relevant annualized benefits for preservation of regional
visibility ar| $1*173 billion and $7.6 billion for the southwest and nation,
respectively.
Clearly, preserving visibility in the Grand Canyon National Park region
also entails certain costs. These include capital expenditures for S02
removal equipment, recurring annual expenditures and the cost of the regulatory
system. The capital expenditures associated with SO removal for all current
and proposed power plants in the region (see Tables h and 5 for listing) are
estimated to be approximately $5.3 billion or between 270 and 560 million
dollars pejj year for real interest rates of three and ten percent and a thirty
year life. In addition, the recurring annual expenditures are estimated to
be 2 billion dollars per year. Finally, the regulatory system cost is approxi-
mately .534 billion dollars per year. Therefore, total costs of currently
planned SO„_ oantrols for the region are between 2.8 and 3.1 billion dollars
annually (T980 dollars). Therefore, national benefits ($7.6 billion annually)
exceed the total control costs and these approximate values indicate that the
currently proposed level of control on S02 emissions are not without some
economic justification.
81
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Table 22
Present value of future benefits
assuming thirty year life span for power
generating plants (in $ Million)
Benefits to" the Southwest from
preserving visibility in
Discount Rate
3% 6% 9%
The Region - Grand Canyon, Mesa
Verde and'Zion National Parks
20,209 11,060
Benefits to the Nation from
preserving visibility in
Discount Rate
3% 6% 3%
The Region - Grand Canyon, Mesa
Verde and Zion National Parks
130,957 93,860 71,667
32
-------
D. Summa ry
There are three especially noteworthy observations which emerge from the
above analysis in Chapters 7 and 8: 1) contrary to conventional thinking,
survey respondents "placed a much higher value on higher levels of visual
clarity than on comparable subsequent decreases; 2) neither past nor anticipated
journeys to the Grand Canyon seemed to be important determinants of preservation
value; and 3) distance from the Grand Canyon had little statistical significance
in explaining the ma^rtitTude of household bids.
Because the Grand Canyon is the dominant feature in a region with many
visitor attractions, one must be especially cautious in extending these
findings to other recreational attractions. It seems likely that there are
only a very few natural phenomena in the United States about which Americans
have such strong feelings. Obvious candidates for this short list would be
Old Faithful (in Yellowstone National Park), and Niagara Falls.
The magnitude of the annual benefits for the region when aggregated
across households is impressive: $889 million in the Southwest and $5.76
billion in the nation. The present value of these benefits streams over
thirty years, discounted at a 3 percent real rate, would be $20.2 billion and
$131 billion, respectively.
In sum, the survey results revealed that Americans place great value on
the preservation of air quality in the Parklands Region and that this valu-
ation is not localized to residents in the Southwest. Further, it was found
that pure existence value overwhelms a substantial user value for the national
parks in the region.
Two qualifications are important in interpreting these results.
First, the accuracy of the survey techniques used in this study to esti-
mate the benefits of preserving visibility in the Grand Canyon Region can be
judged by comparison to other methodologies. Such comparisons suggest that
all available techniques including survey methods, property value, wage and
travel cost studies, are subject to errors of about plus or minus 50 percent
(see Appendix B). It is inherently difficult to quantify environmental values
in dollar terms, but available evidence indicates that the several techniques
available all yield the same order of magnitude of benefits estimates when
applied to the same problem.
Second, the principal benefits of preserving visibility in the Grand
Canyon Region as estimated in this study, derive from the apparent desire of
Americans to preserve a national treasure, whether or not they intend to visit
or use the region themselves. Economists have termed this type of value
"existence value." To our knowledge, this is the first study attempting to
estimate existence values per se. Thus, the methodology used in this study
should be viewed as experimental.
83
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REFERENCES
1. sources for the State data are:
Number of Households: Statistical Abstract of the United States, 1978,
U.S. Department of Commerce.
Incomes: Survey of Current Business, April, 1979, Vol. 59 #4, "County
and Metropolitan Area Personal Income."
Average Age and Race: Current Population Reports, Population Estimates
and Projections.
2. See Illustrative Projections of State Populations by Age, Race and Sex:
1975 to 2000, March 1979, U.S. Department of Commerce, Bureau of the Census.
3. The capital recovery factor is the rate which transforms an initial capital
amount (present value) into a series of equivalent annual amounts, including
both interest and capital.
4. See "Cost Analysis of Lime Based Flue Gas Desul ferization Systems for New
500 Megawatt Utility Boilers," EPA document EPA-450/579003 (January 1979),
prepared by PEDCO Environmental, Inc.
5. Annual regulatory system costs are taken to be equal to the entire 1980
Environmental Protection Agency budget outlays for all air quality programs
plus an equal amount for private sector costs. This IS an obvious over-
estimate of the costs of power plant SO,, control but more refined data
were not avilable. See the Department of Housing and Urban Development
and Certain Independent Agencies Appropriations for Fiscal Year 1980,
Part l-Justifications, hearings before a subcommittee on appropriations,
U.S. Senate, Washington, D.C., 1980.
84
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APPENDIX A
Theory of Visibility "
This discussion is limited to those aspects of visibility addressed in
this study. More complete treatments can be found in Middleton (1 952) and
McCartney (1976). The discussion covers the optics of visibility, and the
contributing role of specific gaseous and aerosol pollutants and the modeling
of visibility.
1) Optics of Visibility
A person sees by the light reaching his eyes from objects. Light is
electromagnetic radiation with wavelengths capable of stimulating the receptors
in human eyes, covering the range of approximately 0.38 to 0.77 um. The amount
of light energy per unit time received per unit area of detector, per unit
solid angle field of view of the detector and per unit wavelength interval at
a specific wavelength (see Figure Al) is called spectral radiance, N. This
spectral radiance is called inherent radiance, N , if the detector is located
at distance, r, from the object. The contrast of a target against its back-
ground, usually the sky. As with radiance, contrast can be described as inher-
ent or apparent, depending on the distance between the observer and the target.
Inherent spectral contrast Co, is defined as:
C
o
(Al)
and apparent spectral contrast, Cr, is defined as:
C
r
(A2)
where tNo = i n h e r e n ^spectraI radiance of the target at zero distance
(watt/m steradian ym)
N
s o = ispectral radiance of the sky at the target
(wau/m steradian ym)
tNr = apparen
(watt'/
£ spectral radiance of the target at
m steradian um)
distance r, and
N
s r = apparent spectral radiance of the sky at distance r from the
target
(wa 11/m2steradian pm)
85
-------
Figure Al
Spectral Radiance
oo
ON
detector area
solid angle
radiant
energy
at some
wavelength X
coming from
object
-------
Contrast is dimensionless because it is a ratio of radiances. The
light coming from a target is attenuated by scattering and absorption (see
Figure A2 and A3). Gas molecules and particulate matter scatter some of the
inherent radiance out of the sight path and absorb another portion. Skylight
and light reflected from the ground is scattered by particulate and gas mole-
cules into the sight path towards the observer (see Figure A4). The result of
these processes is illustrated in Figure A5. A bright object loses radiance
as the distance between it and the observer increases, approaching the limiting
value of the adjacent horizon sky radiance. A perfectly black object has no
inherent radiance. It acquires radiance as the path between it and the observer
increases, again approaching the horizon sky radiance as the limiting value.
A dark object is an intermediate case. The apparent radiance reaching the
observer from a target has two parts, the attenuated inherent radiance and the
path radiance added by scattering from the surrounding air. In equation form,
. .NY + N * (A3)
t N r t o r r
where T = transmittance of light from the target to the observer at distance
r (dimensionless)
N^ = spectral path radiance over distance r(watt/m2sterad ia n ym) .
Similarly, for the apparent background sky radiance,
N = NT + N* (A4)
s r s o r r
If Equation A4 is subtracted from Equation A3, then
„ - N = (N 0 - N ) T (A5)
tNr s r v 0 s o' r v '
Equation AS expresses the fact that the difference in radiance between the
target and sky is transmitted to the observer with the same attenuation as each
image-forming ray of light. If we divide both sides of Equation A5 by the
background sky apparent radiance and multiply the right side of the equation
by N / N , then
1 s o s o'
tNr" SN( \o SNJ SN°
ILLl = JL2 t (A6)
N N N ' v '
s r so s r
Combining Equations Al, A2, and A6, we get the following relation for the
apparent contrast of a target:
N
C = C T (A7)
r o N r
s r
Apparent contrast depends on the inherent contrast of the target, which depends
on the type and amount of vegetation on the target, the illumination of the
87
-------
Figure A 2
'—5—x
/ 2
Scattering
Scattering: Photon on path I is backscattered along path 2.
Photon on path 3 is forward scattering along paths 4 and 5.
Figure A3
X)
Absorption
Absorption: Photon on path 1 is absorbed by the gas
molecule or particle.
88
-------
Figure A4
Sc representation of vision through the
Sunlight
-------
Figure As
The Dependence of Target Radiance on Distance
/N
N
t o
\3/--
\
V °6/
Horizon sky
°^C> *"
k
?/
/
\'C
V
/
/
^
Distance /
90
-------
target as a function of time of day, latitude, longitude, azimuth of the sight
path, azimuth of the normal to the face of the target, and the slope angle of
the target. The ratio of sky radiances at the target and at the observer is
equal to unity for the theoretical assumption of a uniform atmosphere and a
horizontal sight path.
If the atmosphere is homogeneous in composition along the entire sight
path, then the transmission, T^, can be expressed as a function of the extinc-
tion coefficierrt, b -
ext
-b r
T , = e •X1 (A8)
Combining Equations A7 and A8:
C = C0e ' x 1 ( N / N ) (A9)
r 0 xs o s r v ;
If Cr and Co are measured with a tele radiometer and r is known, then Equation
A9 can be solved for the average extinction coefficient:
i C N
r 1 , / o s Ox
b . = — In (7s— —rr-)
ext r N '
r s r
The ratio gN /sN is unity for a horizontal sight path through homoge-
neous air under uniform!" illumination on a flat earth.
Under these same conditions visual range is defined as the distance at
which the apparent contrast of a black target is reduced to 2 percent
( C, - . 0 2 ) . Equation A9 can then be solved for visual range, VR:
VR - 3912 = 3.912^ (A10)
5ex.
r C
r
The choice of 2 percent as the threshold contrast is easily adjusted to
values as high as 5.percent. Middleton (1952) discusses the experiments con-
ducted by others to-derive the threshold contrast. It is important to not
interpret visual range too literally as the distance at which large black tar-
gets disappear. Hence the choice of threshold contrast is not critical but
needs to be consistent for comparing different data sets.
This definition of visual range attempts to account for different dis-
tances between the observer and targets, and different inherent contrasts. It
does not account for targets viewed at different altitudes, for which the
atmosphere has a different clean air (Rayleigh) extinction coefficient.
Measurements of the apparent contrast of targets at different altitudes are
91
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standardized by correcting the total extinction for the Rayleigh component.
This correction is made by subtracting the average Rayleigh extinction c o„f -
ficient of the actual sight path from the measured total extinction and co-
efficient and then adding back the reference Rayleigh extinction coefficient.
This reference is set at .01 km corresponding to an altitude of 1550m
(Elterman, 1 968). Hence standard'visual range SVR, is defined by:
SVR = (All)
1 ,r "o
C ' bext,R + 01
r
where b D = average extinction coefficient of the sight path.
6X1, K
The variables discussed so far describe visibility without reference to
what it would be in a Ray 1 eigh atmosphere, completely unpolluted by natural or
anthropogenic sources. The change in the apparent contrast of a target from
its best possible value in a Rayleigh atmosphere is called delta contrast,
AC, and is defined by:
"bavl. R (z_) r
AC = C - C0e Xt' m
r
Z. ~ zt
where Z =
m 2
= altitude of sight path midpoint (m).
The second term is the apparent contrast of the target computed as if it were
viewed through a Rayleigh atmosphere.
Now that several variables describing visibility have been covered, we
are ready to discuss the physical processes by which particles and gas mole-
cules affect the transfer of light through the atmosphere.
2) Relating Optics to Pollutants
Particulate and gaseous pollutants attenuate light by scattering and
absorption as a function of the gaseous molecular structure, the size and
composition of the particles, and the wavelength of 1 ight. Most absorption is
caused by NX) and carbon particles, while most scattering is caused by parti-
cles. Any c Snges in'source emissions and meteorology that cause higher con-
centrations of 1 ight scattering or absorbing pollutants will result in in-
creased visibility impairment. Scattering usually dominates absorption,
especially in clean air, where 78-95% of the total attenuation is caused by
scattering. Scattering is closer to 55-63% of the total attenuation in highly
polluted urban areas (Weiss, et a I., 1 979). The proportional contribution
of absorption to total extinction (attenuation) can be seen in Fig. A6.
92
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Figure A6
ABSORPTION/EXTINCTION MEASUREMENTS
VERSUS SITE LOCATION
o
H
O
z
H-
UJ
Q.
(T
O
CO
CD
<
1.0
.9
. 8
. 7
.5
. 5
. 4
. 3
. 2
URBAN
[]»
¦t1
_L.
RURAL
ia
0246810121416
SITE
1. Industrial Seattle, WA.
2. Downtown Portland, OR.
3. Industrial St. Louis, MO.
4. Denver, CO. (fairgrounds)
5. Denver, CO. (trout farm)
6. Central Phoenix, AZ.
7. Residential Seattle, WA.
8; Residential St. Louis, MO.
9. Tyson, MO. (1973)
10. Tyson, MO. (1975)
11. Milford, Ml.
12. Hall Mt. AR.
13. Puget Island, WA.
14. Flagstaff, AZ
15. Mauna Loa
Observatory, HI
(After Weiss, et al, 1979)
93
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2-1) Gaseous Scattering
Scattering of gases is treated separately from scattering by particles
because of important differences. Gaseous scattering has an inverse fourth
power dependence on wavelength, which accounts for the blue color of skylight.
In Rayleigh unpolluted air, scattering is the dominant process because the
nitrogen, oxygen, and other gases absorb a negligible amount of visible light.
The Rayleigh scattering by gases depends somewhat on the direction of obser-
vation as shown in F1g. A7> Maximum forward and backward scattering is at
observation angles of 0 and 180, and minimum scattering is at 90°.
More detail on the scattering by an individual gas molecule can be found
in McCartney (1976). If the scattering by air molecules in a specific direc-
tion is summed over all possible directions, the total scattering can be
found. Expressing total scattering as a coefficient, tfcje effect of air with a
molecular density appropriate to sea level is about 10"km .. Hence, Rayleigh
scattering removes about 1% of the incident light per kilometer of horizontal
path. Using Eq. AIO, this Rayleigh scattering coefficient translates into a
visual range of 391 km, assuming no abosrption nor particulate scattering.
Do not expect to see real objects over such distances. Mountains are not black
objects and they are not tall enough to be seen at such distances.
2 - 2) Particulate Scattering
Scattering by particles is more complex in its angular dependence, which
itself depends on the size of the particle. Particulate scattering is often
called Mie scattering, after the scientist who developed the first successful
theory (Mie, 1 980). As particle size decreases, the Mie theory of scattering
approaches the Rayleigh theory, appropriate to particles or gas molecules
smaller than 1/10 the wavelength of light (McCartney, 1976).
The Mie theory was developed for spherical particles of uniform composi-
tion and hence, uniform index of refraction. Ambient aerosol, though, com-
prises spherical, irregular, plate-like, and rod-like particles. In order to
utilize the Mie theory for nonspherical particles, a compromise is made.
Size distributions are measured by some instruments in terms of the aerodynamic
behavior of the particles, from which an equivalent spherical diameter is com-
puted. This diameter is then used in the Mie theory to predict the approxi-
mate scattering of complex shaped aerosol. The angular dependence favors the
forward direction, as shown in Fig. A8, with greater complexity as the particle
size increases.
An important aspect of scattering is the efficiency with which particles
of different size scatter incident light in all directions. The scattering
efficiency factor is defined as the ratio of the total scattering cross-section
and the geometric cjjoss-section. For a spherical particle, the geometric
cross-section is irr , where r is the radius of the particle. The total
scattering cross-section is "that cross-section of an incident wave, acted on
by the particle, having an area such that the power flowing across it is equal
to the total power scattered in all directions" (McCartney, 1376). The
dependence of the scattering efficiency factor on the size parameter, a = 2tv/\,
is shown in Fig. A9. The relative size of the particle with respect to the
94
-------
Figure A7
2 7 0 °
90°
Sun
Observer
Observation
Angle
Rayleigh Scattering Dependence on Observation Angle
95
-------
Figure A8
2 7 0 °
180
a) Particle size - X/4
90°
270°
180°
b) X < Particle size
9 0 °
Observation Angle Scattering Dependence for Particles
(Adapted from McCartney, 1976)
96
-------
Figure A9
1.33
w
O
u
o
>»
o
e
«
G
w
O
u
CO
100
Size parameter, 4
Scattering Efficiency Factor as a function
of Size Parameter, a, and Refractive Index, m
(After McCartney. I976)
97
-------
wavelength of incident light, not its absolute size, is the important indepen-
dent variable, as implied by the use of the size parameter, a. The curve with
index of refraction m - 1.33 represents particles of water, while the m = 1.5
curve approximates silicaor ammonium sulfate, two critical components related
to soil and coal combustion sources respectively. In Fig. A9 the scattering
efficiency factor osci Hates less and lessaround a value of 2 as relative
size becomes very large. At this value a particle refracts, reflects and
diffracts twice the radiant power incident on the geometric cross-section
(McCartney, 1976) . White and Roberts (1 977) found that sulfates and nitrates
in the Los Angeles air basin scattered light more efficiently per unit mass
concentration than other chemical fractions of the ambient aerosol. The high
scattering efficiency of sulfates and the large stationary source emissions of
sulfates led these authors to suggest that this source was comparable with
the automobile in reducing visibility there.
The size of particles and the resulting light scattering is sensitive
to the relative humidity of the air. When the relative humidity rises above
70% water condenses on particles and makes them bigger (Charlson, Waggoner and
Thielke, 1978). The composition of the particle affects the threshold relative
humidity, above which water vapor condenses on the particle. The ratio of
scattering coefficient at any relative humidity to that at 30% is plotted in
Fig. A10.
2-3) Absorption
Absorption of light is the process by which the incident light at specific
wavelengths is converted to internal energy of molecules (rotation, vibration,
and electronic arrangement). A quantum of energy is absorbed for each
discrete change in any of these forms of internal energy. The energy of a
quantum is inversely proportional to the wavelength of the light or other
electromagnetic radiation.
The only absorption of enough consequence in the gaseous air pollutants
from power production is that of nitrogen dioxide, NO ¦ The absorptivity is
the relative loss of incident light per unit length of absorbing path per
unit concentration of pollutant. The absorptivity of N02as a function of
wavelength is shown in Fig. All taken from Hall and Blacet (1 95 2). The
absorptivity is strongest in the blue. Also, there are many detailed absorp-
tion peaks in the overall curve, whose wavelengths correlate with specific
changes in the internal energy of the N02molecule. The strong NQ absorption
of blue light causes plumes and urban hazes to appear brown. Simultaneous
scattering of all wavelengths by particles and scattering of blue by air leads
to a variety of brown, gray, and white colors, depending on the relative
contribution of these processes.
Absorption of light by particles is attributed to their graphitic "soot"
content (Rosen, e t al ., 1979; Wei ss, et al. J 979) • Faxvog and Roessler
(1 978) found that carbon particles were mcst effective in reducing visibility
if their diameters were 15-50% of the wavelength of light. Roessler and
Faxvog (1 980) found that 85% of the acetylene smoke particle attenuation of
514 nm light was caused by absorption and 15% caused by scattering. Roessler
and Faxvog (1981) found that absorbing aerosols increase the visual range com-
98
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Figure A 10
RELATIVE HUMIDITY
Range of variability in Humidogram data averaged
by site; vertically hatched area includes strongly
deliquescent aerosol at Pr. Reyes and Tyson.
(Adapted from Charlson, Waggoner and Thieike, 1980)
99
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Figure All
6
RESOLVED ABSORPTION SPECTRA OF NO,AND NO
2
8
4
NO
0
.25
.30
-.40
.35 Wov»l«ngth ( m)
,50
.45
o
Absorptivity of NO^and 04 v s. wavelength tneosur* at 25 C
Absorptivity of N02as a function of Wavelength of
Incident Light
(After Hall and Blacet, 1952)
-------
puted for light objects viewed against the horizon sky. The dependence of
absorption on the wavelength of incident visible light is quite weak as shown
by the curves in Fig. All (Weiss, et a I., 1 979). The effect of absorption
in optical computations can be expressed in terms of an absorption coef-
ficient, as plotted in Fig. A12.
The processes by which light is attenuated as it moves through air have
been described to help understand the physical measurement of visibility
variables. The di scCiSs Ion now moves on to the way we construct complete
models of visibility as a function of air pollution.
101
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Figure A 12
CHARACTERISTIC ABSORPTION WAVELENGTH
DEPENDENCE MEASUREMENTS
I0"4=
t-
Z R
li I >3
O
U_
u. 2
uj £-
o
o
_ 10
o
t 5
cr
o
to p
CD ^
<
_G
(MILFORD, Ml
n M ,1™ M0
HALL MT, AR
.4 .5 .6 .7
WAVELENGTH (MICRONS)
.8
Absorption wavelength dependence measurements.
(After Weiss et al, 1979)
102
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APPENDIX B
4 ¦ • .
VALUING PUBLIC GOODS: A COMPARISON OF SURVEY AND HEDONIC APPROACHES'
INTRODUCTION
Although the theory of public goods has progressed rapidly since
Samuelson's seminal article (1 954), the empirical measurement of the value of
(demand for) public goods only recently has received increased attention.
Perhaps the best known and most widely accepted empirical approach has been
the use of hedonic prices wherein, for example, it is assumed that either
wages or housing values reflect spatial variation in public good characteris-
tics of different communities. This indirect approach, based on theoretical
work of Tiebout (1956), Lancaster (1 966), Rosen (197*0 and others has proven
quite successful. Among public goods or bads which have been valued using
the hedonic approach are climate [Hoch (1 974)], air pollution [Anderson and
Crocker (1971) and Harrison and Rubinfeld (1978)], social infrastructure
[Cummings, et al. (1978)] and other community characteristics such as noise
level [Nelson (1 979)] and ethnic composition [Schnare (1 976)].
An alternative approach is to directly ask households or individuals
to state their willingness to pay for public goods using survey techniques.
Despite arguments that strategic bias will invalidate survey results, there
exists the need for an alternative to the hedonic approach. As an example,
consider the case of a remote and unique scenic vista, valuable to recreators,
which is threatened by air pollution from a proposed coal fired plant--a
typical situation in the Western United States. Although it is possible, in
principle, to impute the value of clean air and visibility from the relative
decline in local visitation which might follow construction of a power plant,
information on the value of visibility at the site is needed prior to con-
struction for socially optimal decisionmaking on plant location and pollution
control equipment. The hedonic approach is unavailable both because the
scarcity of local population--as opposed to recreators--makes use of wage or
property value data impossible and because scenic vistas may themselves be
unique. For these 'reasons, Randall et al. (1974) first applied survey
methods for valuing visibility and other environmental effects of large coal
fired power plants in the Four Corners region of New Mexico. Since this
initial application, the survey approach has been widely used to value envir-
onmental commodities where market data for hedonic analysis is difficult to
acquire [see, for example, Brookshire, Ives and Schulze (1 976), Rowe, et al.
(1930), and Brookshire, et al. ([1 980]). Other early attempts to
value public goods using the survey approach include Davis (1963), Bohm
(1972) and Hammack and Brown (1 974).
103
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Although results of using the survey approach for estimating the value
of public goods appear to be internally consistent, replicable and consistent
with demand theory [see Schulze et al. (forthcoming) ], no external valida-
tion has been reported (i.e., a comparative analysis using another approach
independent of the survey has not been conducted). Thus, the purpose of this
paper is to report on an experiment designed to validate the survey approach
by direct comparison to a hedonic property value study.
The Los Angeles 'metropolitan area was chosen for the experiment because
of the well defined air pollution problem and because of the existence of
detailed property value data. Twelve census tracts were chosen for sampling
wherein 290 household interviews were conducted during March, 1978. Respon-
dents were asked to provide their willingness to pay for an improvement in
air qual ity at their current location. Air quality was defined as poor,
faiY, or good based both on maps of the region (the pollution gradient across
the Los Angeles Metropolitan Area is both well defined and well understood by
local residents) and on photographs of a distant vista representative of the
differing air quality levels. Households in poor air quality areas were
asked to value an improvement to fair air quality while those in fair areas
were asked to value an improvement to good air quality. Households in good
air quality areas were asked their willingness to pay for a region-wide im-
provement in air quality. The region-wide responses are reported elsewhere
[Brookshire, et al. (1 980)].
For comparison to the survey responses, data was obtained on 634 single
family home sales which occurred between January, 1 977 and March, 1978 ex
clusively in the twelve communities used for the survey analysis. As we show
in the next section, households, in theory, will choose to locate along a
pollution-rent gradient, paying more for homes in clean air areas based on
income and tastes. However, ceteris paribus, we show that the annualized
cost difference between homes in two different air quality areas (the rent
differential for pollution) will in theory exceed the annual willingness to
pay for an equivalent improvement in air quality for a household in the lower
air quality area. Thus, the rent differential associated with air quality
improvement from hedonic analysis of the property value data must exceed es-
timates of household willingness to pay for the survey responses, if the sur-
vey responses are a val id measure of the value of air qual ity improvements.
Section 3 describes the data analysis and experimental design in more detail.
We also conjecture that the willingness to pay for air quality improve-
ments is greater than zero for residents in our sample communities based on
statewide political' support for air quality regulation. The State of
California, principally in response to the air pollution problem in the Los
Angeles Metropolitan area, has led the nation in imposing automobile emis-
sions standards. The automobile industry, under pressure from the Cal ifornia
Legislature, installed the first pollution control devises on California cars
in 1961. This initial step was followed nationally in 1963. Again, Califor-
nia imposed the first exhaust-emission control regulations in 1966, leading
the nation by two years. Over the decade of the 1 970's, California has had
more stringent automotive emission standards than Federallevels, resulting
in higher initial costs and sacrifices in both performance and fuel economy.
104
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In spite of these difficulties, political support, as reflected both in the
State Legislature and in seyeral administrations, has remained strong for
auto emission controls.
In Section k the results of the hypotheses tests are presented. As
Table 2 illustrates, results of the experiment can be summarized as follows:
In the nine census tracts where air quality improvements are possible (poor
and fair commun i ties) , we cannot reject our dual hypotheses that, in each
census tract, household willingness to pay for air quality improvements, as
estimated by surveying households, falls below equivalent property value rent
differentials and lies above zero. We view these results as a qualified
verification of the survey approach for estimating the value of public goods.
Further interpretation of the results is contained in the concluding remarks
offered in Section 5 .
A THEORETICAL BASIS
The property value and the survey approaches for valuing public goods
have received considerable theoretical scrutiny. Property value studies are
conceptually based on hedonic price theory as developed by Rosen (197^) and
recently summarized by Freeman (1979). The survey approach has been modeled
using standard concepts of consumer surplus by Randall et al. (197^)» Bohm
(1972), and Brookshireet al. (1976) where the latter two analyses also
focus on the possibility of strategic behavior. The considerable empirical
evidence now available suggests that strategic bias may be of little conse-
quence both in survey work [See Brookshire et al. (1980) and Rowe et al.
(1980)] and in experimental economics [See Grether and Plott (1979), Scherr
and Babb (1 975) and Smith (1977)]. However, other types of bias may still
inval idate a survey approach for valuing public goods. It has even been
suggested that the survey approach produces "noise" since responses are
purely hypothetical and have no necessary connection to actual budgetary
decisions.
In this section, a simple theoretical model is developed for comparison
of survey responses to a property value study for valuing air quality im-
provements in the Los Angeles region in order to determine if valid public
good measures can be obtained from survey data.
We use the following notation:
Let P = the level of air pollution
x = consumption of a composite commodity excluding housing
c = unit cost or price of the composite commodity X
R = rent or periodic cost of housing
Y = household income
and U(P,X) = household utility, a decreasing function of pollution Up < 0
2
an increasing function of consumption < 0.
105
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Each household maximizes utility, U(P,X), subject to the budget constraint:
Y - CX - R(P) =0
where we assume the existence of a continuous differentiable rent gradient
R(P) . [See Rosen ( 1 974)] for a complete discussion of the generation and
existence of rent gradients. Our model is a simple adaptation of Rosen's,
so we will not elabqrate here.) Two distinct choices are modeled: consump-
tion of the composite commodity, X, and that of housing location by pollution
level, P. Presumably, lower rents will be paid for homes in more polluted
areas, s o R1 (P) <0. The first order conditions for choice of P and Ximply-
t h a t
' P
c 77= R'(P)
UX
or that the marginal rate of substitution between pollution, P, and the
composite commodity, X, valued at the cost of the composite commodity, C,
equals the slope of the rent gradient R' (P) at equilibrium location and
consumption levels.
Figure 1 illustrates the solution graphically and allows us to struc-
ture hypotheses for testing the validity of survey results in comparison to
the property value approach. The vertical axis measures the quantity of the
composite commodity, X, where we assume that the cost, C, of the composite
commodity is unity; i.e., the vertical axis measures dollars as we 11.
Pollution is on the horizontal axis. Given household income Y' , the budget
constraint, shown as Y" - R(P) in Figure 1, is obtained by vertically sub-
tracting the rent gradient, R(P). Thus, household A with preferences shown
by indifference curve 1°. would maximize utility at point "a", choosing to
locate at pollution level P°j consume X° and pay rent R°. If household A's
income were to increase toY , the budget constraint would shift vertically
to Y - R(P) and the same^household would relocate, choosing point "b", at
a lower pollution level P with higher consumption, X' , given tastes as
represented by indifference curve "I .. Alternatively, anotherlurt'^focatinc?'
with, income Y°, but tastes as shown By I ^ would choose point tgs^es ancj
at P as well, but choosing lower consumpiTon a . Thus, both
income enter location decisions over pollution levels.
The survey approach used in the Los Angeles metropolitan area to
obtain an estimate'of the value of air quality asked households how much, at
most, they would be willing to pay for an improvement in air quality at the
site where they presently live. Thus, the household in equilibrium ^t point
"a" in Figure 1 was asked how much X it would forego to experience P
rather than PO while maintaining the same utility level. Presumably, house-
hold A would be indifferent between points "a" and "c" and be willing to pay
w dollars (or units of X) to achieve a reduction in air pollution of A P .
Unfortunately, as is illustrated in Figure 1, the budget constraint, Y" R(p),
obtainable by estimating the rent gradient functio^, R(p), does not provide
information on the bid for improved air qua'llty, W . Rather, the change in
106
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rent between locations with air quality levels P° and P', A R injure],
must, for any household located at "a", equal or exceed the bid/t , if the
second order conditions for the household optimization problem are generally
satisfied. Thus, we can establish an upper bound on the willingness to pay
for air quality improvement by examining the rent gradient. For example, if
household B had a lower income, "Y ,'it would locate at point "e". Even though
household B is now located at pollution leve^ P" like household A, its bid
for an air quality improvement AP would be W , smaller than W yet still less
than AR. Thus, if survey bids are a valid measure of willingness to pay for
air quality improvements then AR > W.
This hypothesis holds for each household even if we consider the case
of multiple housing attributes. Including other attributes such as square
footage of the home, bathrooms, fireplaces, neighborhood characteristics,
etc., denoted by the vector Z, the model is revised as follows:
Max U (\, P, x)
St. Y - Cx - R (Z, P) = 0
4
with first order conditions
1 = Rp(Z,P)
^ *
Ut
and C jp- = R|(Z,P).
A
These first order conditions constitute, along with frequency distributions
for housing characteristics and household preferences, a system of partial
differential equations which solve for R(Z,P). Thus, a hedonic rent gra-
dient is defined for pollution, P, and other household characteristics,!,
as well.
As is illustrated in Figure 1, in which housing characteristics other
than pollution are not incorporated, budget constraints for different house-
holds are obtained by vertically shifting the same rent gradient. Thus, all
households face the same rent differential AR for a change in pollulgh ('e^el
AP even though willingness to pay for that change may differ, i.e., W #' W .
However, turning_^o Figure 2, household A, located at P", may occupy a house
with attributes T while household 9ga1so located at P° may occupy^a house
wftih a different set of attributes Z . Household A, with income';* would
then face a rent gradient like that shown in Figure 2 defined by R(Z , P) and
choose point "a", but household B with income"? , would now face a different
rent gradient of R(?, P) and choose to locate at point "b". Therefore,
households with different housing characteristics may face different rent
gradients over pollution when projected in the (X, P) plane. In general, AR,
unlike the case shown in Figure 1, will no longer be constant across house-
holds at the same location. However, for each household i,(i = A, B in
Figure 2), it is still true that the rent differential, AR , for a change in
107
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pollution AP, calculated for the fixed vector of housing characteristics ? ,
will exceed that household's willingness to pay, W , 'for" the same change in
pollution level at the same location. Note that households were asked their
willingness to pay with the specific assumption that they remained in the
same house and location. Thus,-^ , for a particular household was truly fixed
--allowing the simple analysis in the (X,P)p]ane as shown in Figure 2.
The first hypothesis for testing the validity of the survey approach
can be constructed as follows: for each household i in a community, A"R:' >W .
It then follows that in each community the average rent differential_across
households, AR, must equal or exceed the average willingness to pay W for an
improvement in air quality. In other words, if survey bids are a valid mea-
sure of willingness to pay, then for each community in our sample, AR>W,
i.e., average willingness to pay cannot exceed the average rent differential.
Our second hypothesis is that, given the political history of air pollution
control in the State of California as described in the introduction, mean
bids in each community are non-negative, W > 0.
Our dual test of the validity of survey measures must remain somewhat
imprecise because hedonic rent gradients themselves only provide point
estimates of the marginal rates of substitution (slopes of indifference
curves) between pollution and other goods (money) for individuals with pos-
sible differing tastes and income. One does not have information necessary
to estimate, for example, the shape of 1". in Figure 1 solely on the basis of
the slope of the budget constraint, •?,\(P°7, at point "a". Attempts to esti-
mate individual willingness to pay (w in Figure I) from hedonic rent gra-
dients must thus introduce strong assumptions about the nature of preferences.
(See, for an example of an hedonic approach which derives willingness to pay
by making such assumptions, Harrison andRubinfeld [1978],
SAMPLING AND DATA ANALYSIS
The previous section has presented a theoretical framework for a com-
parison between the survey technique and the property value approach for
valuing public goods. In order to empirically implement the comparison, the
two approaches require a consistent sampling procedure. This section de-
scribes the sampling procedure and results of the separate studies.
Sampling was restricted to households within the Los Angeles metropoli-
tan area. The first concern was air pollution data. Air monitoring stations
are located throughout the Los Angeles area providing readings on nitrogen
dioxide (NC^), total suspended particulate matter (TSP) and other pollutants.
The objective was to relate as closely as possible the readings of two con-
stituents of air pollution (N02and TSP) to census tracts used both for the
property value and survey studies. The air shed was divided to the follow-
ing air quality regions: "good" (N02< 9 pphm) (TSP < 90 yg/m ); "fa^i r", (NC^
9-11 pphm) (TSP 9-110 yg/m')V a-nd "poor" (NO^ > 11 pphm) (TSP >110 yg/m ) •
Improvements from poor to fair and fair to good across the region are each
associated with about a 30% reduction in ambient pollution levels. Consid-
eration was given to wind patterns and topography of the area in making these
distinctions.
108
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Many variables may affect the value households place on air quality.
To control for as many of these as possible in advance of the actual experi-
ment, the sample plan identified six community pairs where each pair was
relatively homogeneous with respect to socioeconomic, housing and community
characteristics, yet allowed for a significant variation in air quality.
The property value analysis attempts to provide external validation for
the survey approach. The absence of such validation explains in our view,
the lack of general 'acceptance of survey.techniques. The objective, then, is
to estimate the hedonic rent gradient R(z, P) and calculate rent differen-
tials associated with the poor-fair and fair-good air quality improvements
for sample census tracts. These results are then utilized for comparison to
the survey results.
A hedonic rent gradient wia_s estimated in accordance with literature as
recently summarized by Freeman (1979)• Housing sale price is assumed to be
a function of housing structure variables (1 iving area, bathrooms, fire-
places, etc.), neighborhood variables (crime rate, school quality, population
density, etc.), accessibility variables (distance employment to centers and
beach) and air quality as measured by total suspended particulate (TSP) or
nitrogen dioxide (NO?). The primary assumption of the analysis is that
variations in air po lution levels as well as other household, neighborhood
and accessibility attributes are capitalized into home sale price. Implicit
or hedonic prices for each attribute are then determined by examining housing
prices and attribute levels.
The property value analysis was conducted at the household level in
order to provide an appropriate comparison to the survey instrument. Thus ,
the household data used were at the micro level of aggregation and include a
large number of characteristics.9 Data was obtained for sales of single
family homes which occurred between January, 1 977 and March, 1 978 in the
communities used for the survey analysis. In addition to the immediate attri-
butes of the household, variables which reflected the neighborhood and com-
munity were included to isolate the independent influence of air quality dif-
ferentials on home sale price.
as indicated by MSler (1977) even under the Presumption of correct
model specification, estimation of a single equation hedonic rent gradient
may be hindered by severe empirical difficulties, primarily multi-collinear-
ity. With respect to this problem, in each of three data categories — house-
hold, neighborhood, and air quality--multi-collinearity forced the exclusion
of variables and the usage of proxy variables. For instance, collinearity
between number of rooms, number of bedrooms and living area as quantitative
measures of house size allowed the use only one--living area which serves as
a proxy for all. Further, since housing density and population density mea-
sure essentially the same phenomenon, only the former is used in the esti-
mated equations. The estimation procedure was not able to separate out the
independent influence of each air pollutant. Thus, only one pollution me a
sure, either NO^ or TSP, was utilized to describe the level of air quality.
In order to provide information concerning the sensitivity of our analysis,
results are presented for each of these pollutants. Finally, contrary to
expectation a collinearity problem did not exist between distance from beach
109
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and air pollution. This can be attributed, in part, to the success of the
sample plan in isolating the effects of air quality.
Two alternative nonlinear specifications are presented in Table 1 al-
ternatively using NC^ or TSP to represent pollution level A number of as-
pects of the equations are worth noting.
First, approximately 90% of the variation in home sale price is ex-
plained by the variation in the independent variable set. Second, with only
a minor exception, all coefficients possess the expected relationship to the
dependent variable and are statistically significant at the one percent
level. The exception is the crime rate in both the NO- *uid TSP equations.
Third, in their respective equations, the log form of the pollution variables
have the expected negative influence on sale price and are highly significant.
The estimated relationship between house sale price and pollution is there-
fore consistent with the graphical analysis of Section 2; that is, the rent
gradient is convex from below in the pollution/dollars plane. Finally, the
stability or relative insensitivity of the regression coefficients to the
particular pollution variable indicates that individuals have an aversion to
pollution in general rather than to any one pollutant.
Estimation of the rent gradient was also completed using other forms of
the pollution variables (linear, squared, cubic). Whereas the squared and
cubic terms did not demonstrate statistical significance, the first order
terms performed only marginally worse than the log formulation. Rent dif-
ferentials have also been calculated for these and other forms with results
nearly identical to those presented here.
The next step was to estimate the rent differential AR. for each indi-
vidual household for each census tract. The rent differential! specifies the
premium an individual household would have to pay to obtain an identical home
in the next cleaner air region (poor to fair for six communities, fair to
good for three communities). Due to the estimated functional form of the
rent gradient, the talc u'Jated rent differential is dependent upon the value
of all other variables. The average home sale price change based on indi-
vidual data in each census tract associated with an improvement in air Qual-
ity, c_eteris paribus., is shown in column two of Table 2 of the next section.
Column one of Table 2 lists communities by air quality level. The table
only shows for the log-linear NO. equation since, as noted above, other
specifications give nearly identical results. The figures shown are derived
by evaluating the hedonic housing expression, given the household's charac-
teristics, for a pollution change from poor to fair or fair to good as the
case may be. The resulting sale price differential is then converted to an
equivalent monthly pyment through the standard annualization procedure and
division by twelve.'2 S i n ce our hypothesis test is posed in terms of the
average rent differential in the relevant communities, then a community mean
and standard deviation are calculated. Column three of Table 2 shows the
number of homes for which data was available to calculate average rent dif-
ferentials and standard deviations for each community. Monthly rent differ-
entials ranged from $15-^ to $45.92 for an improvement from poor to fair air
quality and $33.17 to $1 28.46 for an improvement from fair to good air qual-
ity. The higher figures in each case are associated with higher income com-
110
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muni ties. Again, these average differentials should provide an upper bound
for the survey results.
The survey approach followed the work of Davis (1963) and Bohm ( 1 9 7 2 )
in gathering the information necessary for estimating a Bradford (1 972) bid
curve. The approach involves the establishment of a hypothetical market via
a survey instrument. Through the work of Randall, et a I., (197^) and
Brookshire, et a I., (1 976), the necessary structure for constructing a hypo-
thetical market for the direct determination of economic values within the
Hicksian cornsumer surplus framework has been developed. The survey reported
here is consistent with this previous literature.
The hypothetical market was defined and described both in technical
and institutional detail. The public good (air quality) was described by
the survey instrument to the respondent in terms of easily perceived levels
of provision such as visual range through photographs'-* and' maps depicting
good, fair and poor air quality levels over the region. Respondents had
little difficulty understanding the levels of air quality represented to them
because of the sharp pollution gradient across the region.
Payment mechanism: 4 were specified within the survey instrument and
the respondent was asked to react to alternative price levels posited for
different air quality levels. In every case the basis for the bid for better
air quality was the existing pollution situation as determined by location of
their home shown on a map of the Log Angeles metropolitan area which depicted
regional air quality levels. Various starting points for the bidding prices
and differing information structures were included in the survey format.
Biases from alternative starting points and informatioii|^:ructures were not
present in the. results [See Brookshi re, et al. ( 1 9 8 0 ) ] .
The survey was conducted over the period of March, 1978. A total of
290 completed surveys were obtained^|or the above mentioned areas. Sampling
was random within each paired area.
Table 2 in the next section presents the mean bids and standard devia-
tions and number of observations in Columns four and five respectively for
each community for an improvement in air quality. Two types of bids are pre-
sented: proposed improvements from poor to fair air qua' ity and from fair to
good air quality. In poor communities--EI Monte, Montebello and La Canada--
the mean bids ranged from $11.00 to $22.06 per month. F°r 'J16 ^a'r communi-
ties—Canoga Park, Huntington Beach, Irvine, Culver City, Encino and Newport
Beach communities--the mean monthly amounts range from $5.55 to $28.18 to
obtain good air quality.
TEST OF HYPOTHESES
The previous sections have described a theoretical structure and two
different empirical estimation techniques for determining the value of urban
air quality improvements in the Los Angeles metropol itan area. The theoreti
cal relationship between the valuation procedures (AR >_W) and the hypothesis
that survey bids are non-zero (W > 0) are tested in this sect ion.
111
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Table 2 presents the community average survey bids (column four) and
corresponding rent differentials (column two). As is indicated, in each com-
munity the sample survey bids are non-zero and less than the calculated rent
differentials in absolute magnitude. This establishes that the survey bid
bounds are consistent with our theoretical arguments but does not indicate
statistical significance, which is provided below.
With respect to the test of equality of mean survey bids to zero, Table
2 (column six)" presents the experimental results. The calculated t-statistics
indicate rejection of the null hypothesis (that the population mean, y— equals
zero at the one percent level in every community sampled.) These resuYts are
in accordance with the political situation of the region and indicate that
individual households are willing to pay amounts significantly greater than
zero for an approximate 30% improvement in air quality.
The comparison of the survey bids to the estimated rent differentials
is presented in Table 2 (column seven). In this instance the compound hypo-
thesis that population average rent differential (equals or exceeds the
population average survey bid (Wjj) is again tes'tedusing the t-statistic.
Rejection of the null hypothesis reqiines that the calculated t-statistics be
negative and of sufficient magnitude. ' The standard t-test calculations
(column seven, Table 2) imply that the hypothesis cannot be rejected
for the population means and yrj even at the 10% cri tical 'level. Although
we present only the results for ttre hedonic housing equation in which log
(no2) is the pollution measure, these results remain essentially unchanged for
afl" communities, for all estimated hedonic rent gradients, regardless of the
variable (N02or TSP) utilized as a proxy for the general state of air qual-
ity. The results then are quite insensitive to the particular hedonic model
specification, providing a degree of generality to the results.
The hypotheses tests indicate that the empirical analysis is entirely
consistent with the theoretical structure outlined above. This conclusion,
when combined with the absence of any identified biases [see Brookshire, et al.
(1 980)] suggests that survey responses yield estimates of willingness to pay
for environmental improvements in an urban context consistent with a hedonic-
market analysis. A further implication is that individual households demon-
strated a non-zero willingness to pay for air quality improvements rather
than free riding. This conforms to the previous survey results of Brookshire,
et al. (1976) and Rowe, et al. (1980) as well as the experimental work of
Scherr and Babb (1975), Smith (1977) and Grether and Plott (1979) concerning
the role of strategic behavior. This seems to indicate that the substantive
effort to devise a- payment mechanism free of strategic incentives for con-
sumers [see Groves and Ledyard (1977)] has been directed towards solving a
problem not yet empirically observed. However, the conclusions of this
experiment are not without qualifications. In the next section possible limi-
tations of survey analysis and conclusions concerning the efficacy of employing
surveys to value a wide range of non-market commodities are discussed.
112
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CONCLUSION
There are a number of limitations in generalizing our results to all
survey work. First, this experiment was conducted in the South Coast Air
Basin where individuals have both an exceptionally well-defined regional pol-
lution situation and a well-developed housing value market for clean air. The
effect of clean air on housing values appears to be exceptionally well under-
stood in the Los Angeles metropolitan area. Thus, the Los Angeles experiment
may be a special case in which an informed populace with market experience for
a particular public good allowed the successful application of the survey
approach. In particular, situations where no well-developed hedonic market
exists may not be amenable to survey valuation. Biases due to lack of exper-
ience must then be considered a possibility. However, existing studies by
Randall et al. (1 974) and Brookshire et al. (1 976) and Rowe et al. (1 980) of
remote recreation areas certainly suggest that survey approaches provide
replicable estimates of consumer's willingness to pay to prevent environmental
deterioration, without prior valuation experience.
In summary, this paper set out to both theoretically and empirically
examine the survey approach and to provide external validation for survey
analysis. The theoretical model described in Section 2 predicts that survey
responses will be bounded below by zero and above by rent differentials de-
rived from the estimated hedonic rent gradient. In order to test the dual
hypotheses a survey and a traditional analysis of the housing market were
undertaken. Each was based upon a consistent but random sampling procedure
in the Los Angeles Metropolitan area. The empirical results do not allow the
rejection of either of the two hypotheses, thereby providing evidence towards
the validity of survey methods as a means of determining the value of public
goods .
113
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Composite
Commodity
y 1 - R (P)
Ye R(P)
fwl
AR
X?--
AR
P1
P°
P
V
AP Air Pollution
Figure 1
With identical housing attributes the identical rent differential, AR, exceeds
individual willingness to pay, WA and W&.
H4
-------
Composite
Commodity
AR
AR
0
p- p»
"V
AP Air Pollution
Figure 2
With differing housing attributes across households each individual rent differential
exceeds that households willingness to pay.
115
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TABLE 1
Estimated Hedonic Rent Gradient Equations'
Dependent Variable= Log (Home Sale Price in $1,000)
Independent
NO Equation
TSP Equation
Variable
i.
Housing Structure Variables
Sale Date
.01859?
.018654
(9.7577)
(9.7727)
Age
-.018171
-.021411
(2. 3385)
(-2.8147)
Living Area
.00017568
.00017507
(12.126)
(12.069)
Bathrooms
.15602
.15703
(9.609)
(9.66361
Pool
.058063
.058397
(A.6301)
(4.6518)'
Fireplaces
.099577
.099927
(7.1705)
(7.1866)
Neighborhood Variables
Log (Crime)
-.08381
-.10401
(-.5766)
(-1.9974'
School Quality
.0019826
.001771
(3.9450)
(3.5769)
Ethnic L.opposition
.027031
.043472
-(Pe cent White)
(4.3915)
(6.2583)
Hous ng Density
-.000066926
-.000067613
(9. 1277)
(-9.2359)
Pub] c Safety Expenditures
.00026192
.00026143
(4.7602)
(4.7418)
Accessibility V a r i a b I e s
Distance to Beach
-.0 11586
-.011612
(-7.8321 )
(7.7822)
Distance to Employment
-.28514
-.26232
(-14.786)
(14.15s)
Air Pollution Variables
log (TSP)
-.22183
-.22^07
(-3.8324)
log (No,)
(4.0324)
Constant
2.2325
l .0527
(2.9296)
(1 • '~ 5 3 7)
RZ
¦»g
.89
Sum of Squared Residuals
18.92
18.97
Degrees of Freedom
619
619
at - Statistics in Parentheses
116
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Table 2
Tests of Hypotheses
a
roperty Value Results
Survey
Results
Tests of Hypotheses
Commuri i ty
& R
(Standard
Deviation:
dumber 0 f
observations
W
(Standard
Deviation
Jumber 0 f
observation!
t-statistics
»«g > Ob
-statistics
U— > u_C
A R - yw
Poor - Fair
El Monte
15,44
(2.88)
22
11.10
(13.13)
20
3.78
1.51
Montebel 10
30.62
(7.26)
49
11.42
(15.15)
19
3.28
7.07
La Cafiada
73.78
(48.25)
51
22.06
(33.24)
17
2.74
4.10
Sample
Population
45.92
(36.69)
122
14.54
(21.93)
56
4.94
5.54
Fair ¦ Good
Canoga Park
33.17
(3.88)
22
16.08
(15.46)
34
6.07
5.07
Huntington
Beach
47.26
(10.66)
44
2k.2k
(25.46)
38
5.92.
5.47
Irvine
48.22
(8.90)
196
22.37
(19.13)
27
6.08
5.08
Culver City
54.44
(16.09)
64
28.18
(34.17)
30
5.42
11..85
Encino
128.^6
(51 .95)
45
16.51
(13.38)
37
7.51
12.75
Newport
Beach
77.02
(41 .25)
22
5.55
(6.83)
20
3.63
7.65
Sample
Population
59.09
(34.29)
393
20.31
(23.0)
l 86
12.02
14.00
'Rent differentials for the hedonic housing equation in which log fJO 2) 's ,he relevant
pollution variable are presented here. Essentially identical resi ts are obtained using
N 0 2, TSP or log(TSP).
"The hypotheses to be tested were Ho : = 0; H] : > 0. All test statistics indicate
rejection of the null hypothesis at the significance level.
cThe hypotheses to be tested were Ho : Uj-r- > ; Hj : Vj-r-
-------
REFERENCES
1. David S. Brookshire, Mark A. Thayer, William D. Schulze and Ralph C. d'Arge
(forthcoming in the American Economic Review).
2. Alternatively we could define the utility function U(-P, X) which
would be an increasing quasi-concave function of both arguments.
3. Primes or subscripts denote derivatives or partial derivatives
respectively throughout the paper.
4. The second expression is, of course, a vector of conditions, one
for each attribute.
5. For a continuous model one could specify a taste parameter in the
utility function and specify a distribution of households over that
parameter. To complete a closed model one also needs the distribution
of housing units over characteristics.
6. The paired areas with associated census tract marker and air qual-
ity level are respectively (1) Canoga Park - #13^5 - fair/El Monte -
#4334 poor, (2) Culver City - #2026 - f a i r / M o n t e b e 11 o - #4301.02
and part of #5300.02 - poor, (3) Newport Beach - central #630.00 -
fair/Pacific - northeast portion of #2627*02 and southwest inter-
section - good; (4) Irvine - part of #525 - fair/Pales Verdes -
portion of good; (5) Encino - portion of ft 1 3 2 6 - fair/La
Canada - south-central portioof #4607 - poor; (6) Huntington Beach
- central portion of #993.03 poor/Redondo Beach - eastern portion
of #6205.01 and #6205.02 - good. For a map showing the monitoring
station locations in relation to the paired sample areas and the air
quality isopleths see Brookshire, et al. (1 980).
7. The estimation of a hedonic rent gradient requires that rather re-
strictive assumptions are satisfied. For Example, MSler (1 977), has
raised a number of objections to the hedonic property value approach
for valuing environmental goods. These include the possibility that
transaction costs (moving expenses and real estate commissions) might
restrict transactions leaving real estate markets in near constant
disequilibrium; and that markets other than those for property alone
might capture part of the value of an environmental commodity. The first
of these criticisms is mitigated by the extremely fluid and mobile real
estate market of the late 1 970's in Los Angeles, where rapidly escalating
real property values increased homeowner' equity so quickly that
"housejumping" became financially feasible. The second of MSler's
concerns, that other prices, e.g.,golfclub fees and wages capture
part of the willingness to pay can be addressed empirically. For
example, attempts to test if wages from our survey data across the
Los Angeles area reflected differences in pollution level produced
negative results.
118
-------
8. Note that we use sale price or the discounted present value of the
flow of rents rather than actual rent as the dependent variable.
Given the appropriate discount rate the two are interchangeable.
9. Housing characteristic data was obtained from the Market Data
Center, a computerized appraisal service with central headquarters
in Los Angeles, California.
10. Although" the nonlinear equations provide large t 'values on the air
pollution coefficients, the coefficients on the pollution variables
in the linear-equations possessed the expected relationship and were
significant at the ]% level. Also, the calculated rent differentials
associated with the linear specifications were larger than those from
the nonlinear equations.
11. [t should be noted that the nonlinear estimated equations will give
biased but consistent forecasts of rent differentials. However, the
linear estimated equations in all cases forecast larger rent differentials
than the nonlinear estimated equations presented here.
12. A capital recovery factor equal to .0995 which corresponds to the
prevailing .0925 mortgage rate in the January, 1979 - March, 1978
period is used.
13. In developing photographs, two observational paths from Griffith
Observatory in Los Angeles were chosen: (1) toward downtown Los
Angeles, and (2) looking down Western Avenue. The approximate visi-
bility (discernible objects in the distance, not visual range) for
poor visibility was 2 miles, for fair visibility 12 miles, and for
good visibility 28 miles.
14. Payment mechanisms are either of the lump sum variety, or well
specified schemes such as tax increments or utility bill additions.
The choice in the experimental setting varies according to the
structure of the contingent market.
15. Questions have been raised as to problems of biases in the survey'
approach. Strategic bias (i.e., free rider problems), hypothetical
bias, instrument bias all have been explored. Generally speaking,
problems of bias within the survey approach have not been prevalent.
For a general review of the definition of various biases and results
of d if f e r e n t - ex pe r i m e n t s see Schulze et al. (forthcoming) and for
investigations of strategic bias utilizing other demand revealing
techniques see Scherr and Babb (1 975) andSmith (1 979).
16' Interviewer bias was not present. No records were kept that would
enable the testing for non-respondent bias.
17. For instance, rejection of the null hypothesis u^-) at the
one percent level would require a calculated t-statistic less than
-2.326 given a large number of observations. Since none of the
calculated t-statistics are negative the null hypothesis cannot be
rejected [See Guenther (1 973)].
119
-------
BIBLIOGRAPHY
Anderson R., and T. Crocker, "Air Pollution and Residential Property Values,"
Urban Studies, October 1971, 8, 171-80.
^™ *
Bohm, P., "Estimating Demand for Public Goods: An Experiment," European
Economic Review, 1972, 3, 11-130.
Brookshire, D., R. d'Arge, W. Schulze and M. Thayer, "Experiments in Valuing
Public Goods," Advances in Applied Macroeconomics, cd., V. Kerry Smith,
jai press, 1980: LJ
Brookshire, D., B. Ives and W. Schulze, "The Valuation of Aesthetic Prefer-
ences," Journal of Environmental Economics and Management, December
1976, 3, 325-3^6.
Bradford, D., "Benefit Cost Analysis and Demand Curves for Public Goods,"
Kyklos, November 1 972, 23, 775-782.
Cummings, R., W. Schulze and A. Meyer, "Optimal Municipal Investment in Boom-
towns: An Empirical Analysis," Journal of Environmental Economics and
Management, September 1978, 5, 252-267.
Davis, R., "Recreation Planning as an Economic Problem," Natural Resources
Journal, October 1963, 3, 239-2^9.
Freeman III, A. Myrick, "Hedonic Prices, Property Values and Measuring Environ-
mental Benefits: A Survey of the Issues," Scandinavian Journal of
Economics, 1979, 81, 154-173.
Grether D., and C. Plott, "Economic Theory and the Preference Reversal
Phenomenon, 11 American Economic Review, September 1979, 69, 623-638.
Groves T., and J. Ledyard, "Optimal Allocation of Public Goods: A Solution to
the 'Free Rider' Problem," Econometrics, May 1977, k5, 78 38 09.
Guenther, W., Concepts of Statistical Inference, McGraw-H! 1 11973*
Hammack J., and G. Brown, Waterfowl and Wetlands: Toward Bioeconomic Analysis,
Baltimore: John Hopkins University Press 197^.
Harrison, D., Jr. and D. Rubinfeld, "Hedonic Housing Prices and the Demand for
Clean Air," Journal of Environmental Economics and Management, March
1978, 5, 81-102.
120
-------
Hoch ,1. with T. Drake, "Wages, Climate, and the Quality of Life," Journal of
Environmental Economics and Management, December 197^» 1, 268-295.
Lancaster, K., "A New Approach to Consumer Theory," Journal of Political
Economy, April 1 966, Ik, 1 32-1 57.
Maler, K., "A Note on the Use of Property Values in Estimating Marginal
Willingness to Pay for Environmental Quality," Journal of Environmental
Economics and 'Management, December 1977, k, 355-369.
Nelson, J., "Airport Noise, Location Rent, and the Market for Residential
Amenities," Journal of Environmental Economics and Management, December
1979, 6, 320-331.
Rowe, R., R. d'Arge and D. S. Brookshire, "An Experiment in the Value of
Visibility," Journal of Environmental Economics and Management, March
1 980, 7, 1 -1 9.
Randall, A., B. Ives and C. Eastman, "Bidding Games for Valuation of Aesthetic
Environmental Improvements," Journal of Environmental Economics and
Management, August 197^, 1, 132-149.
Rosen, S., "Hedonic Prices and Implicit Markets: Product Differentiation in
Pure Competition," Journal of Political Economy, January/February 197^>
82, 34-55.
Samuelson, P., "The Pure Theory of Public Expenditures," Review of Economics
and Statistics, November 195^, 36, 387-389.
Scherr B., and E. Babb, "Pricing Public Goods: An Experiment with Two Proposed
Pricing Systems," Public Choice, Fall 1 975, 23, 35~^8.
Schnare, A., "Racial and Ethnic Price Differentials in an Urban Housing
Market," Urban Studies, June 1976, 13, 107-120.
Schulze, W., R. d'Arge and D. S. Brookshire, "Valuing Environmental Commod-
ities: Some Recent Experiments," Land Economics (forthcoming subject
to revisions).
Smith, v., "The Principle of Unanimity and Voluntary Consent in Social Choice,"
Journal of Political Economy, December 1977, 85, 1 1 25-1 1 40.
Tiebout, C., "A Pure Theory of Local Expenditures," Journal of Political
Economy, October 1956, 65, 416-424.
121
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APPENDIX C
VISIBILITY QUESTIONNAIRE
URBAN SURVEY: Economics Narrative
We are students at the University of Wyoming [New Mexico," Chicago] and
are conducting this survey for a research project designed to help in valuing
visibility in the national parks in the Southwestern United States.
The Clean Air Act, passed by Congress in 1970, declared a national goal
of preserving the scenic beauty and pristine air quality of our national parks
and wilderness areas.
Air quality, or the "cleanness" of the air, can be affected by either
natural occurrences (e.g. dust and humidity) or by man-caused pollution (such
as autc emissions or emissions released by industrial facilities). Conse-
quently, visibility, which is the ability to see and appreciate distant
objects, activities, scenes, or atmospheric phenomena, can be affected by
either natural or man-caused pollution sources resulting in changes in the
color and clarity of near and far distant vistas.
As you can see in these photographs taken at the Grand Canyon, air pol-
lution can discolor a view to the point where its components cannot be clearly
identified and its scenic beauty cannot be fully enjoyed by the viewer [SHOW
GRAND CANYON PHOTOGRAPHS: SITUATION A-E].
These photographs represent five levels of visibility during morning
and afternoon periods looking both east and west from Hopi Point at the Grand
Canyon. Column A represents poor visibility, B below average, C average
visibility, D above average, and E good visibility. Comparing the columns,
we can see the variety of air quality conditions and resulting levels of vis-
ibility that can be observed in the Grand Canyon. The rows represent the
different vistas while standing at Hopi Point. The first row represents the
different visibility and air quality conditions looking east, in the morning
from Hopi Point. The second row represents morning conditions looking west
from Hopi Point. The third row shows the view from Hopi Point in the after-
noon looking west.
122
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PAST AND FUTURE USE
In the first part of our survey, we would like to ask a few questions
about your use of the National Parklands.
El) How many days have you spent visiting the Grand Canyon National Park
in the last 10 years? Plesse put an X by the number of days on your answer
sheet for question El.
E2) How many days do you expect to spend visiting the Grand Canyon
National Park in the next 10 years? Please put an X by the number of days on
your answer sheet for question E2.
E3) How many days have you spent visiting National Parks in the South-
west (Arizona, Utah, New Mexico, and Colorado) in the last 10 years? Please
circle the number of days by each National Park on your answer sheet for
question E3.
Ek) How many days for each National Park do you expect to visit in the
next 10 years? Please circle the number of days by each National Park on
your answer sheet for question Ek.
[FOR EXISTENCE VALUE ANALYSIS, TURN TO PAGE 7 AND BEGIN WITH QUESTION E8. FOR
USER ANALYSIS (EVERY THIRD INTERVIEW), CONTINUE WITH QUESTION ES. NOTE:
NUMBER OF VISITS MUST BE GREATER THAN ZERO IN QUESTIONS El AND E2 TCRTONDUCT
USER ANALYSIS.]
123
-------
GRAND CANYON ANALYSIS
- U ser-
This part of the surveyis designed to determine how much you are will-
ing to pay to improve visibility in the area of Grand Canyon National Park.
Although one does not usuallyplace a dollar value on scenery, sunsets,
or visibility, such things are valuable to most people. Since it does cost
money to clean up man-made pollution to improve visibility in our National
Parks, we are interested in firiding out how much good visibility is worth to
you .
First let's assume that visitors to Grand Canyon National Park are to
pay for improvements in the air quality and therefore in the visibility, by
paying an increase in daily entrance fees to be admitted into the park. Let's
also assume that all visitors to the park would pay the same total daily fee
as you would. Then, all the additional money collected would be used to fin-
ance the air quality improvements represented in the photographs.
Again, let us look at the photographs representing the different levels
of visibility and air quality ranging from very poor (A) to very good (E) for
east and west views in the morning and afternoon from Hopi Point in the Grand
Canyon. We would like to know how much you are willing to pay as a total
daily park entrance fee for your household for air quality improvements and
resulting visibility improvements shown in Columns B through E. When deciding
how much you are willing to pay for each improvement, you will always be com-
paring the improved air quality to the lowest air quality conditions as
represented in Column A. Also, when considering how much you are willing to
pay for each improvement, assume each photograph represents the visibility on
a day that you would be visiting the Grand Canyon National Parks.
[SHOW COLUMNS A-B]
E5) This is Column A, representing very poor air quality and visibility.
Please indicate on your answer sheet how much of an increase above the total
daily park fees of $2.00 per carload you would be willing to pay for your
household to improve the visibility to that shown in Column B. Put a B next
to the highest dollar amount you would pay per day if you were visiting the
Grand Canyon in question E5 on your answer sheet.
[m 0 ve COLUMN cto cover b]
124
-------
Now, for your household, how much of an increase above the total daily
park entrance fees of $2.00 per carload for your household would you pay for
cleaner air if the visibility was improved from that shown in Column A to.
that shown in Column C? Please put the letter C next to the highest amount
you would pay per day in question ES on your answer sheet.
[MOVE COLUMN D TO COVER c]
For your household, how much of an increase above the total daily park
entrance fees of $2.00 per carload would you be willing to pay for an improve-
ment from Column A to Column D? Please put the letter D next to the amount
in question £5<
[MOVE COLUMN E TO COVER COLUMN D]
And finally, for your household, how much of an increase above the total
daily park entrance fees of $2.00 per carload would you pay to have air qual-
ity and visibility conditions on a day of your visit to Grand Canyon be like
Column E as compared to Column A? Put the letter E next to the amount you
would pay as a daily park entrance fee in question E5 on your answer sheet.
125
-------
REGIONAL ANALYSIS
-User-
Unless new and current industrial facilities in the Southwest are
required to utilize air pollution controls for particulate and sulfur oxide
emissions, visibility in the region will become less than the current average.
Let's look at some pictures representing regional visibility. Columns
A-E again represent air quality conditions from very poor (A) to very good
(E). The rows represent morning conditions for the Grand Canyon, Mesa Verde
and Zion National Parks. Row 1 looks out from Hopi Point towards the east in
the morning at the Grand Canyon. Row 2 represents the vista from Hess Verde
at Far View overlook towards the south in the morning. Finally, Row 3 is at
Lava Point in Zion National Park looking southeast in the morning.
If current emission standards are maintained, the average conditions
will be as seen in Column C. If, however, current emission standards on
existing and proposed industrial facilities are relaxed or not enforced, then
average air quality and visibility in the region will be represented as in
Column B. As shown in Column B a deterioration in visibility would occur in
the Grand Canyon, Zion and Mesa Verde National Parks. As a result, conditions
as represented in Columns C, D, and E will occur less frequently. Conditions
in Columns A and B would occur more frequently. We would like to know how
much the maintenance of average regional air quality and visibility is worth
to you.
E6) How much would you be willing to pay per day in addition to existing
park entrance fees for your household at the Grand Canyon, Mesa Verde, or
Zion National Parks to prevent a deterioration in visibility in the region as
represented in moving from Column C to Column B. [SHOW PHOTOGRAPHS AND POINT
TO COLUMNS C AND B FOR GRAND CANYON, MESA VERDE AND ZION.] Assume that
entrance fees would be raised throughout the National Parks in the Southwest.
Please put an R next to the dollar amount closest to the highest increase in
daily entrance fees you would be willing to pay for your household for a
region-wide preservation in visibility for question E6.
E7) If you answered "$0" to any part of questions E5 or E6, please
answer question E7 on your answer sheet.
[TURN to p Age 11, question El 1 (PLUME USER ANALYSIS) ]
126
-------
EXISTENCE VALUE ANALYSIS
-Grand Canyon-
This part of the survey is designed to determine your' concern for pre-
serving visibility levels in Grand Canyon National Park.
Although one does not usually place a dollar value on scenery, sunsets,
or visibility, such things are valuable to most people. Since it does cost
money to clean up man-made pollution to improve visibility in our National
Parks, we are interested in finding out how much good visibility is worth to
you .
Unless new and current industrial facilities in the Southwest are
required to meet current emission standards for particulate and sulfur oxides,
air quality in the Grand Canyon will become less than the current average.
Again, let us look at the photographs representing visual air quality
ranging from very poor in Column A to very good in Column E for east and west
views in the morning and afternoon from Hopi Point. If current emission
standards are maintained the average conditions will be as seen in Column C.
[f, however, the current emission standards for sulfur oxide are not enforced,
then average air quality and visibility in the region will become like Column
B. As a result, conditions are represented in Columns C, D and E will occur
frequently in the Grand Canyon. Such emission controls will likely make
electricity more expensive.
E8) We would like to know if you would be willing to pay higher electric
utility bills if the extra money collected would be used for additional air
pollution controls to preserve current air quality and visibility levels at
the Grand Canyon. How much extra would you be willing to pay at most, per
month as an increase in your electric utility bill to preserve current aver-
age visibil ity as represented in Column C rather than have the average deter-
iorate to that shown in Column b? Please put an X next to the highest amount
you would be willing to pay per month for your household on your answer sheet
for question E8. [EMPHAS IZE THEY ARE ANSWER ING E8. ]
127
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EXISTENCE VALUE
-Regional Analysis-
Unless new and current industrial facilities in the Southwestern United
States are required to utilize air pollution controls for particulate and
sulfur oxide emissions, visibility in the region will become less than the
current average.
Let's look at some pictures representing regiona 1 vi s i bi 1 i tv. Columns
A-E again represent air quality conditions from very poor (A) to very good
(E). The rows represent morning conditions for the Grand Canyon, Mesa Verde
and Zion National Parks. Row 1 looks out from Hopi Point towards the east
in the morning at the Grand Canyon. Row 2 represents the vista from Mesa
Verde at Far View overlook towards the south in the morning. Finally, Row 3
is at Lava Point in Zion National Park looking southeast in the morning.
If current emission standards are maintained the average conditions will
be seen in Column C. If, however, current emission standards on existing and
proposed industrial facilities are relaxed or not enforced, then average air
quality and visibility in the region will be represented as in Column B. As
shown in Column B a deterioration in visibility would occur in the Grand
Canyon, Zion and Mesa Verde National Parks. As a result, conditions as
represented in Columns C, D and E will occur less frequently. Conditions in
Columns A and B would occur more frequently. We would like to know how much
the maintenance of average regional visibility is worth to you.
E8) How much more than you have already offered to pay for the Grand
Canyon would you be willing to pay in higher electric utility bills per month
to preserve current average air quality and visibility levels throughout the
Parklands of the Southwest? Visibility conditions as represented in the photo-
graphs in Column C would be maintained as opposed to allowing air quality and
visibility to deteriorate to the new average levels shown in photographs in
Column B. Please place an R by the increase in monthly electric utility bills
you would be willing to pay for your household for question E8.
E9) If you answered "$0" to E8, please answer E9 on your answer sheet.
[TURN Top Ag e 11 , QUEST I ON E1 2 (PLUME Ex i sT e n c e value)]
128
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PLUME ANALYSIS (USER)
E10) Problems other than regional haze can be associated with industrial
development in the Southwest region. Plumes also can reduce visibility by
disrupting a vista on the horizon. These photographs represent two situations
whereby in picture A no plume can be seen looking west from Hopi Point in the
Grand Canyon. Pciture B is identical, however, a plume is visible. We would
like to know how much you are willing to pay in addition to the daily park
entrance fees of $2.00 for your household for prevention of plume blight over
the Grand Canyon. Please put the letter A next to the highest dollar amount
you wouId pay per day if you were visiting the Grand Canyon for question E10
on your answer sheet.
[CONTINUE WITH SOCIO-ECONOMIC QUESTIONS ON THE LAST PAGE OF ANSWER SHEET]
129
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PLUME ANALYSIs (EXISTENCE VALUE)
En) Problems other than regional haze can be associated with industrial
development in the Southwest region- Plumes can reduce air quality and impair
visibility by visually disrupting a vista on the horizon. We would like to
know if you are concerned with preserving visibility in Grand Canyon National
Park from plume blight.
These photographs represent two situations whereby in picture A no plume
can be seen looking west from Hopi Point in the Grand Canyon. Picture B is
identical, however, a plume is visible. Again focusing on the possibility of
higher utility bills, how much extra would you be willing to pay at most,
monthly, as an increase in your electric utility bill to preserve the vista
as seen in picture A rather than have plume blight as represented in picture
B? Please put the letter A next to the highest amount you would be willing
to pay per year for your household on your answer sheet for question En.
[CONTINUE WITH SOC IO-ECONOMIC QUEST IONS ON LAST PAGE OF ANSWER SHEET]
130
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ANSWER SHEET
El)
E2)
1 Day
2 Days
3 Days
4 Days
1 Day
2 Days
3 Days
4 Days
5 Days
6 Days
7 Days
8 Days
5 Days
6 Days
ubys
8 Days
9 Days
10 Days
11 Days
12 Days
9 Days
10 Days
11 Days
12 Days
13 Days
1A Days
15 Days
More than 15 Days
13 Days
14 Days
15 Days
More than 15 Days
E3) Zion Nat. Park 123456789101112 13 14 15 More than 15
Mesa Verde Nat. Park 123456789101-112 13 14 15 More than 15
Bryce Canyon Nat. Park 1 234567891 0 11 12 13 14 15 More than 1 5
Canyonlands Nat. Park 123456789101112 13 14 15 More than 15
E4) Zion Nat. Park 123456789101112 131415 More than 15
Mesa Verde Nat. Park 123456789101112 13 14 15 More than 15
Bryce Canyon Nat. Park 123456789101112 13 14 15 More than 15
E5) $
E6)
. 0 0
.50
1.00
1.50
2.00
2.50
3.00
$ .00
.50
1.00
1.50
2.00
2.50
3.00
/day
_/day
_/day
I day
"/day
_/day
/day
$4.00
5.00
6.00
I day
_/ day
/day
_/day
_/day
/day
/day
9.00
10.00
S 4.00
5.00
6.00
7.00
8.00
9.00
10.00
/day
$ 15.00
/ day
/ day
20.00
/ day
/ day
25.00
/ day
/day
50.00
/ day
/day
75.00
/day
/ day
100.00
/dav
/day
More than
$100.00
/ day
$ 15.00
/day
/ day
20.00
/day
/day
25.00
/day
/dav
50.00
/day
/day
75.00
/day
/day
100.00
/day
/day
More than
$100.00
I day
I day
131
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Answer Sheet 2
E7) Answer only i f you answered $.0 0 to the above questions. Did you bid zero
because you believe that:
The air quality improvements represented in the columns are not
significant.
The source' of the air pollution should be required to pay the costs
of improving the air quality.
Other (specify)
E8)
$ .00
/ year
$25.00
/ year
5.00
/ year
30.00
/ yea r
10.00
/yea r
35.00
/yea r
15.00
20.00
/year.
/ year
40.00
45.00
/ year
/ year
E9)
$ .00
5.00
/yea r
$25.00
/ year
/ year
30.00
/yea r
10.00
15.00
/yea r
/ year
35.00
40.00
/ yea_ r
/ year
20.00
/year
45.00
/ year
$50.00
60.00
90.00
$50. oo
60. oo
70. oo
80 .oo
90.00
/yea r
$100.(X)
/yea r
/yea r
125.00
_ / year
/ year
150.00
/yea r
/yea r
175.00
/ year
/ year
200.00
/year
More than
$200.00
/ year
/yea r
$100.00
/ year
/year
125. 00
/yea r
/ year
150. 00
/year
/year
175.00
/ year
/year
200.00
/ year
More than
$200.00
/yea r
E10) Answer only if you answered $.00 to the above questions,
because you believe that:
Did you bid zero
The air quality improvements represented in the columns are not
significant.
The source of the air pollution should be required to pay the costs
of improving the air quality.
Other (spec i f y )
En) $ .00
.50
1.00
1.50
2._"
2.5
3.00
_/ day
J day
_/day
/day
_/day
"/day
/day
$4.00
5.00
7.
8.00
9.00
10.00
_/d ay
"/day
_/day
_/day
_/day
_/day
I day
$ 15.00
20.00 /
25.00
50.00
_/day
_a y
I day
/day
75.00 /day
100.00 /day
More than $100.00
/day
132
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Answer Sheet 3
E12)
$.00
.50
1.00
1.50
2.00
2.50
3.00
_/ dav
/day
_/dav
/day
_/day
/dav"
/day
E13)
El4)
E15)
1 time
2 times
3 times
1 time
_2 times
_3 t
mes
$ .00
5.00
10.00
15.00
20.00
E16) Home z p code
E18) Education:
$4.00
5.00
6.00
7.00
8.00
_/day
_/ day
_/day
_/day
_/d a y
/day
/day
15.00
20.00
25.00
/
I day
day
I d
5 0.0/0 d
75.00 —
100.00
More than $100.00
_a y
_/day
I day
_4 t mes
t mes
6 t mes
7
M m e s
_8 times
i m
e s
4 times
j m e s
6 times
1 times
8 times
_/yea r
_/ year
_/ year
_/year
_/year
$25.00
30.00
t
mes
45:00
_/year
_/ y e a r
_/ year
_/yea r
_/ year
$50.00
60.00
E17)
90.00
Rural
_/ year
J year
_/year
_/ year
_/ year
Suburban
under 12 years
High School
College - no degree
Bachelor's degree
Post-graduate degree
day
_10 times
11 times
12 times
10 times
11 times
12 times
$100.00
125.00
150.00
175.00
200.00
More than $200.00
_/ year
_/ year
_/yea r
_/ year
_/year
_/year
Urban
E19) Age group: under 18
18-24
25-34
45-54
55 & over
E20) Sex:
Male
Female
E21). How many me hers are there in your household? persons
E22) Are you the primary income earner in your household? yes
us
E23) Would you p ease indicate, which of the following groups your annual house-
hold income falls in:
- $
less than $5,000
$ 5,000-7,499
7,500-9,999
$1 0,000-1 4,999
| $1 5,000-1 9,999
$20,000-24,999
$25,000-29,999
$30,000-34,999
$35,000-39,999
-$40,000-4
-$4 5, 000-49.999
$50,000-54,999
$55,000-59,999
'$60,000-64,999
'$65,000-69,999
9-9$ 9 0 ,000-74,999
$75.000 and up
I 33
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INTERVIEWING SUPPLEMENT
[Additional information to be used by interview teams only if necessary.
Please note on answer sheet if this material was used!]
Scientific Basis of Photographs
The photographs you have been shown have been produced in the following
manner: Throughout the National Park System, photographs are being taken
twice a day (morning and afternoon) every day of the year at major overlooks.
Sophisticated electronic equipment, an instrument called a telephotometer, is
used to get a physical measure of visibility at the same time the photos are
being taken. This physical measure is called apparent contrast. Apparent
contrast is a measure of visual air quality. This measure is based on the
difference in light between a distant target (a mountain, for instance) and
the background sky. Apparent contrast can also be measured directly in the
photographs, which allows calibration between physical measurements and the
photographs. As a result of this data collection effort, we know how often
conditions shown as in columns A-E occur over a typical year.
What Causes Poor Visibility
Humidity (water in the air), dust (especially fine particulate), and
the gasses making up the atmosphere themselves all reduce visibility. Man-
caused pollution can contribute to poor visibility. Two types of fine particu-
late are partly caused by man: sulfates and nitrates. Emissions of nitrogen
oxides (gasses formed from atmospheric gasses under high temperature and/or
pressure) react in the atmosphere to form nitrates. Both automobiles 3nd
industry are major sources of nitrogen oxides. Emissions of sulfur oxides
(gasses resulting from, for example, a combination of sulfur in fuels or ores
with oxygen) also react in the atmosphere to form sulfates. Industry, espe-
cially power plants and smelters, is the primary source of sulfur oxide emis-
sions. The contribution of sulfates and nitrates to poor visibility has been
determined by taking air samples during known visibility conditions and running
the air sample through a filter to capture particulate matter. Sulfates and
nitrates have been :shown to make a significant contribution to the visibility
problem. Records from airports in the Southwest show that visibility has
declined from an average of about 100 miles to about 80 miles over the last
twenty years.
134
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BIBLIOGRAPHY
Billings, C. 1980. 'Personal Communications from the Air Pollution Control
Division, Arizona State Department of Health Services.
Brookshire, D., B. Ives and W. Schulze. 1976. "The Valuation of Aesthetic
Preferences," Journal of Environmental Economics and Management, 3 ( 4 )
December.
Brookshire, D., R. d'Arge, W. Schulze and M. Thayer. 198l . "Experiments in
Valuing Public Goods," Advances in Applied Macroeconomics, ed. V. Kerry
Smith, Greenwich, Corm.: JAI Press, Inc., 1 (1 ): 1 23-1 72.
Brookshire, D., M. Thayer, W. Schulze and R. d'Arge. 1982. "Valuing Public
Goods : A Comparison of Survey and Hedonic Approaches," American Economic
Review (forthcoming).
Charlson, R.J., A.P. Waggoner and J.F.Thielke. 1978. Visibility Protection
for Class I Areas, Report to Council on Environmental Quality.
Christian, J. 1980. Personal Communication to Nevada Division of Environ-
mental Protection, June 3 .
Clean Air Act Amendment. 1977- P. L. 95-95, August 7•
Copeland, J.O. 1979- Environmental Protection Agency memorandum to Steve
Eigsti , July 1 7 .
Elterman, L. 1968. UV, Visibi lie and lr Attenuation for Altitudes to 50 km,
NTIS report AD671933-
Energy Impact Associates. 1979. Update Report.
Environmental Protection Agency. 1979. Protecting Visibility, an EPA report
to Congress, EPA-450/5-79-008 October.
Faxvog, F.R. and D.M. Roess ler. 1978. "Carbon Aerosol Visibility vs. Particle
Size Distribution," Applied Optics 17(16): 2612-2616, August.
Fleck, L. 1980. Phone communication to Tucson Electric Power Company, July 11.
Freeman, A. Myrick, III. 1979* "Hedonic Prices, Property Values and Measuring
Environmental Benefits: A Survey of the issues," Scandinavian Journal
of Economics, 8 1! 154-73.
135
-------
Grether, D. and C. Plott. 1979• ' Economic Theory and the Preference Reversal
Phenomenon," American Economic Review 69:623*368, September.
Hall, T.C., Jr. and F.E.BIacet. 1952. "Separation of the Absorption Spectra
of N02a n d N20 4 in the Range of 2400-5000A, Journal of Chemical Physics
20(11): 1 7^5" 17^9, November.
Krutil la, J.V. 1967». ".Conservation Reconsidered," American Economic Review,
57, September.
Latimer, D.A., T.C. Daniel and H. Hugo. 1980. Relationships Between Air
Quality and Human Perception of Scenic Areas, Systems Applications
Incorporated, San Rafael, California.
Macias, E.S., D.L. Blumenthal, J.A. Anderson and B. K. Cantrel 1 . 1979.
"Characterization of Visibility-Reducing Aerosols in the Southwestern
United States: Interim Report on Project VISTTA," MR I 78-IR-1585» January.
Macias,E.S. and R. Husar. 1976. "A Review of Atmospheric Particulate Mass
Measurement Via the Beta Attenuation Technique," Fine Particles, ed.
B.Y.H. Liu, New York: Academic Press.
MSler, K.G. 1974. Environmental Economics, Baltimore: Johns Hopkins Press.
Maim, W.C., K. K. Leiker and J.V. Molenar. 1980a. "Human Perception of Visual
Air Quality," Journal of the Air Pollution Control Association, 3 0(2):
122-131, February.
Maim, W.C., K. Kelley,J.V. Molenar and T.C. Daniel. 1980b. "Human Perception
of Visual Air Quality (Uniform Haze)"; pending publication in
Atmospheric Environment.
Maim, W.C., E.G. Walther, K. O'Dell and M. Kleine. 1980c. "Visibility in the
Southwestern United States from Summer 1978 through Spring 1979,"
Submitted to Atmospheric Environment and available from the Visibility
Research Center of the John Muir Institute, Department of Physics,
University of Nevada, Las Vegas, NV 8 9 1 5 4.
Marians, M. and J. Trijonis. 1979. "Empirical Studies of the Relationship
Between Emissions and Visibility in the Southwest," E P A - 4 5 0 / 5 7 9 0 0 9 .
McCartney, E.H. 1976. Optics of the Atmosphere. New York: John Wiley and
Sons, Inc.
Middleton, W.E.K. 1952. Vision Through The Atmosphere. University of
Toronto Press.
Mie, G. 1908. "A Contribution to the Optics of Turbid Media, Especially
Colloidal Metallic Suspension," Ann. phys. 25(4): 3774 4 5. German.
136
-------
Mitre Corporation. 1979- National Environmental Impact Projection No. 1,
HCP/P-6119, February.
Moon, D. 198 0. Phone communication to Salt Rive Project, July 9.
Randall, A., B. Ives and E. Eastman. 1974. "Bidding Games for Valuation of
Aesthetic Environmental Improvements, Journal-of Environmental Economic
Management 1:132-149.
Roberts, E. 1980. Phone communication to Arizona Public Service Company,
June 30.
Roess ler, D.M. and F.R. Faxvog. 1980. "Photoacoustic Determination of Optical
Absorption to Extinction Ratio in Aerosols," Applied Optics 19(4): 578-
581, February.
Roessler, D.M. and F.R. Faxvog. 1981. "Visibility in Absorbing Aerosols,"
Atmospheric Environment 15: 151-155.
Rosen, N., D.D.A. Hansen, L.Gundel and T. Novakov. 1979. "Identification of
the Graphitic Carbon Component of Source and Ambient Particulate by
Raman Spectroscopy and an Optical Attenuation Technique," Proceedings
of Carbonaceous Particles in the Atmosphere, March 20-22, 1978, available
from Laurence Berkeley Lab, University of California.
Rowe, R., R. d'Arge and D. Brookshire. 1980. "An Experiment on the Economic
Value of Visibility," Journal of Envi ronmental Economics and Management
7 (I), March.
Samuel son, P.A. 1954. "The Pure Theory of Public Expenditures," Review of
Economics and Statistics 36(4):337"389» November.
Schulze, W., R. d'Arge and D. Brookshire. 1981. "Valuing Environmental
Commodities: Some Recent Experiments," Land Economics, May.
Smith, V. 1977- "The Principle of Unanimity and Voluntary Consent in Social
Choice," Journal of Political Economics 85:1125"! 140, December.
Syzedek, L. 1980. Personal communication to Nevada Power Company, June 19*
Waggoner, A.P., R.E. Weiss, N. C. A1 qu i st, D. S. Cobert and R. J. Charlson. 1981.
"Optical Characteristics of Atmospheric Aerosols," Atmospheric
Environment in press.
Walther, E.G., W.C. Maim and R. Cudney. 1978. "The Excellent but Deteriorating
Air Quality in the Lake Powell Region," report avai 1able from 1 h e Visi
bility Research Center of the John Muir Institute, Department of Physics,
University of Nevada, Las Vegas, NV 89154, July.
Walther, E.G. and D. Comarow. 1979. Report on a Preliminary Survey of Proposed
Major Emitting Facilities that may Affect NPS Class I Areas, Visibility
Research Center, John Muir Institute, Department of Physics, University
of Nevada, Las Vegas, NV 8 9 1 5 4.
137
-------
Walther, E.G. andW.M. Carey. 1980. "The occurrence of Haze, Photographed from
Mesa Verde National Park Towards Hogback Mountain, New Mexico," report
submitted to the New Mexico Health and Environment Department, from the
Visibility Research Center, John Muir Institute, Department of Physics,
University of Nevada, Las Vegas, NV 8 9 1 5 4.
Weisbrod, B.A. 1964. "Collective-Consumption Services of Individual Consump-
tion Goods," Quarterly Journal of Economics 7 8 ( 3 ) .
Weiss, R.E., A.P. Waggoner, R. J. Charl son, D.L. Throsel 1, J.S. Hall and L.A.
Riley. 1979. "Studies of the Optical, Physical and Chemical Properties
of Light Absorbing Aerosols," P roceed i ng s of Carbonaecous Particle in
the Atmosphere, March 20-22, 1 97 8 , available from Laurence Berkeley
Lab, University of California.
White, W.H. and P.T. Roberts. 1977- "0" 'he Nature and Origins of Visibility-
Reducing Aerosols in the Los Angeles Air Basin," Atmospheric Environment
11:803-812. E
138
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