| 2.1 | Study Scoping Objectives |
Because relatively few studies have addressed the economic benefits of preserving cultural resources, there is very little background on how to define a good such as injury reductions. Consequently, we started the study with a scoping effort to review what is known about the injury processes and the affected resources. During the scoping phase, we also evaluated alternative economic methods to value the change in injury to the resource, including revealed preference and stated preference methods. As part of our scoping effort, we conducted several informal interviews and focus groups to learn about the public's perceptions of the value of monuments and their preservation. The results of the literature review and scoping interviews were reported in the project work plan (1995), and discussed with the study expert panel.
The research team recognized at the onset that we needed specific research questions that were manageable within the resources available for this study, and that would contribute to this research topic for the NAPAP assessment process. Because the issues related to the effects of Title IV on the economic value of cultural resources are complex and varied, it was clear that we would need to be selective about what was to be pursued for this study, and that many important questions would remain.
The first task in a valuation study is to define the specific change in the quantity or quality of a good or service that is to be valued. In valuation studies this is referred to as "defining the good." For this study, this meant working out the details of what cultural resources would be included in the valuation exercise, and what the change in these resources is that is expected to be achieved with the Title IV required emissions reductions. It also meant selecting an economic valuation method and developing a workable plan for applying this valuation method.
| 2.2 | Study Scoping Process |
Primary activities during the scoping phase included reviewing the relevant scientific and economic literature; establishing definitions for monuments, erosion, and chemical alteration; selecting the specific type and geographic scope of the resource to be valued; testing methods for describing the injury to cultural resources to the general public; and defining the good for the valuation exercise. The scoping phase of the study included the following efforts:
The purpose of the literature review process was to familiarize the research team, whose backgrounds are primarily in economics, with what is known about the physical effects of air pollution on materials that are used to construct cultural resources, to review what has already been done with regard to the valuation of cultural resources, and to review available economic approaches applicable for this topic. With these goals in mind, an exhaustive review of the scientific literature on the effects of pollution on materials was not conducted. Literature reviews published in 1990 in the State of Science and Technology series (NAPAP, 1990 a, b, c) were relied upon, augmented by conversations with several of the lead authors on these reviews, and reference to a few publications available since the NAPAP reviews were completed.
During the scoping phase, we developed several draft components for our survey instrument. These included descriptions of monuments, marble monuments, and the set of Washington, DC marble monuments. Draft descriptions of erosion and chemical alteration were also developed, as well as draft descriptions of the preservation options. Finally, our draft instrument contained several questions about the nature of value for monuments and how injuries affect value. Reactions to these presentations, and responses to these preliminary questions helped us in defining the good and developing the presentation for the final valuation exercise.
| 2.3 | Summary of Economics Literature for Valuing Cultural Resources |
Early in the scoping process, as we thought about the different types of cultural resources that might be affected by air pollution, such as monuments, historic buildings, and outdoor sculpture, we recognized that it was necessary to narrow the focus of this study to one category of cultural resources. Differences in the function and purpose of various types of resources make it difficult to generalize about how changes in air pollution-related injury affect the value of the resource. We decided that monuments would be a good candidate for research because they are less complicated in their function than buildings, which have combined public and private value and provide many functional services unrelated to external visual appearance. Monuments also seemed to be a resource category of more potential interest and value to the general public than resources that would be defined as sculpture, although these are not mutually exclusive resource categories. The following discussions therefore focus on monuments.
Consumers derive many types of benefits from the preservation of cultural and historic monuments. If they visit a monument, they may experience use benefits in the form of educational and aesthetic benefits. Even if they do not visit a particular monument, they may derive benefits from its preservation by knowing that other people can visit, enjoy, and learn from it, or from indirect use such as viewing photographs, TV images, or other representations of the monument. In both instances, we expect that the economic value is primarily derived from human use, either direct or indirect, of the resource, now and in the future.
There are two conventional concepts of economic value: willingness to pay (WTP) and willingness to accept (WTA). Both are individual-based concepts. WTP for a monument is the amount an individual would be willing to pay (above what they already pay) to have the monument. WTA is how much the individual would have to be compensated to voluntarily accept the elimination of the monument. WTP is the appropriate measure of value if the individual has no presumed right to the continued existence of the monument. WTP is the measure of value most commonly estimated, not necessarily because it is always the conceptually correct measure, but because it is typically easier to estimate than WTA. WTA questions used in stated preference approaches often raise ethical objections by respondents that make the questions difficult to answer, especially with regard to public goods.
The value to society of preserving a monument is the sum of the individual WTP (or WTA) over all members of society. Monuments and the benefits they provide are public goods, which means that the benefits one individual accrues from a monument are not diminished by the accrual of benefits to others, with the possible exception of congestion impacts associated with visitation. Therefore, unlike private goods, individual WTP must be summed to determine society's value. This has important implications for what can be determined about society's value for a monument from its construction and maintenance costs.
Past benefit valuation efforts related to air pollution injury to materials have primarily used the avoided maintenance cost approach to estimate the benefits of reduced SO2 emissions (For example, Mathtech, 1983; Horst et al., 1986; Lareau et al., 1986; Choi et al., 1990; and Horst etal., 1990). They compared baseline maintenance schedules and costs that were based on pollution levels predating the 1990 Clean Air Act Amendments with projections of schedules and costs for reduced SO2 emissions scenarios. For instance, reduced acid deposition might lead to slower corrosion of metal surfaces, which would require less frequent cleaning or less frequent applications of a protective surface coating. This valuation approach uses changes in the time path of maintenance costs to estimate the benefits of the policy.
Maintenance and mitigation costs are not the same as WTP to prevent or reduce the injury, but under some circumstances they may be equivalent. In other circumstances, maintenance or mitigation costs may be a lower bound for WTP to prevent the injury. There are, however, also circumstances when maintenance or mitigation costs may exceed WTP. The key factors in determining the relationship between these costs and WTP to prevent the injury are:
In the case of publicly owned resources, it may not be appropriate to assume that observed maintenance expenditures tell us anything about the consumers' benefits from the quality of the resource that is being maintained. Budget constraints, institutional decision making processes, and differences in preferences between caretakers and consumers could all lead to actual maintained quality being either above or below the level that maximizes welfare.
Maintenance expenditures may be inadequate measures of benefits because there are many instances in which maintenance and repair activities cannot fully offset injury from air pollutants, i.e., the injury is irreversible. Furthermore, some maintenance activities offset some types of injury, but aggravate other injury processes. For example, cleaning a marble statue may increase erosion. In these instances, some consumer benefit may be lost due to the irreversibility of the injury or the irreplaceability of the original monument material.
It appears from our review of the physical injury caused by SO2 and acid deposition on marble monuments that they fit into this last category. The injury to marble cannot be fully offset short of full replacement of the material, and some maintenance activities that offset one type of injury cause an acceleration of another type of injury. In addition, monuments may be a type of resource for which there is value in the original material such that full replacement and replication may not restore the full benefit to the consumer.
For this study, we focus on estimating WTP for reductions in injuries to monuments. We found very few studies that have estimated WTP for preserving cultural resources. Two conducted in Europe used contingent valuation approaches and focused on specific historic buildings. These studies found substantial WTP values by visitors and local residents for reducing air pollution injuries to specific historic buildings.
Grosclaude and Soguel (1994) obtained WTP values for local building maintenance in Neuchâtel, Switzerland. In 1992, they conducted in-person interviews with 200 of the approximate 32,000 residents. Respondents were shown pictures of 16 local limestone buildings that were listed with the Department for the Conservation of Monuments and Historic Sites, and exposed to traffic pollution. The pictures showed the entrance facade of each building and a close-up of the average amount of dirt or soiling on the material. Respondents were asked to select the buildings whose conditions required maintenance. An open-ended valuation question obtained WTP for maintenance through voluntary monthly contributions to a fund for the selected buildings. Of the 200 respondents, 86 reported a WTP of zero, but through follow-up questioning about half of these zeros were determined to represent free-riding behavior1 and thus not "true" zero values. Econometric analysis was used to estimate an average bid for all respondents who were concerned about building condition, correcting for free-riding behavior. The resulting predicted mean monthly bid for respondents who did not give "true" zero bids was SFr10. Based on this value, annual WTP per household was estimated at SFr120 ($851992US$), which was multiplied by 14,034 households (i.e., 89% of total households; the remaining 11% were assumed to have true zero values for WTP). Predicted total annual WTP for maintenance was SFr7 million ($6.1 million 1992 US$). On average, the respondents selected six buildings from the initial 16 for maintenance. Dividing total WTP by the number of selected buildings suggests annual WTP per building of SFr283,000 ($246,000 1992 US$).
Navrud (1992) reported results from a study by Navrud, et al. (1992) that estimated WTP values for visitors to the Nidaros Cathedral in Trondheim, Norway, using an open-ended value elicitation format. Estimated WTP to preserve the original structure by reducing air pollution injuries was 318 NOK ($51 1992 US$) per visitor as a one-time payment. A slightly lower WTP value of 278 NOK ($45 1992 US$) per person was obtained for the option of restoring the church and replacing the original parts. Navrud (1992) also notes that the 65% of the respondents who indicated that "the original meant more to them than the restored object" had significantly higher WTP values for preservation. The study tested for part-whole bias by comparing total WTP for all Norwegian cultural heritage with the WTP for the Nidaros Cathedral and concluded that the bias was less of a problem than suspected. Finally, most of the average WTP value was attributed to "preservation motives" rather than "use" value.
These valuation studies suggest that willingness to pay for cultural materials are measurable and potentially quite larger, and passive use value is potentially more important than direct use value. Aside from this, however, their usefulness is limited because they cannot be transferred to the current study, and because the goods presented in the studies are different from the good we anticipate valuing.
| 2.4 | Summary of Physical Injury Literature Review for Carbonate Stone |
All cultural resources that are exposed to the outdoor environment are subject to some degree of weathering injury. There are three main causes of weathering (Sherwood, 1995):
Early in the literature review process we narrowed our focus to carbonate stone (marble and limestone) because it is a commonly used material for constructing cultural resources and because the injury from air pollution is not easily mitigated (injury to bronze can be minimized with a coating treatment).
Two key questions guided the review of the injury:
Carbonate stone contains calcium carbonate, or calcite, CaCO3. Calcite is chemically reactive with water, as well as SO2 and related air pollutants. There are two categories of SO2-related injuries to calcite (NAPAP, 1991; Sherwood, 1995):
The dissolution and alteration injuries described above are the two primary microscopic processes that contribute to the macroscopic manifestations that are visible to people: erosion, spalling, cracking, and soiling. NAPAP research efforts have attempted to develop dose-response relationships for dissolution and erosion. Although some quantitative information is available from these efforts, widely accepted dose-response functions have not been established for dissolution or alteration. Further, quantitative relationships between microscopic effects and macroscopic changes have not been established. Even if changes in rates of dissolution and alteration effects expected as a result of Title IV were quantifiable, these relationships would not necessarily reflect the impact of these changes on the function and aesthetic quality of the structure. For example, if a monument's purpose is to convey information in the form of an inscription, e.g., as in the case of a funerary monument, it may be able to perform its function in spite of some degradation of surface detail. In contrast, an area of architectural detail whose purpose is primarily aesthetic may not be able to sustain similar erosion without a loss of value.
Another approach in the literature that takes one aspect of function into account is the estimation of critical thickness. Critical thickness is defined as the depth of surface necessary for the intended function of the material (NAPAP, 1991). This, of course, varies with how the material is used. For example, critical thickness may be measured by the depth necessary to be able to read an inscription. The concept of critical thickness gives us some idea about the functional life expectancy of carbonate stone materials, but it does not reflect changes in the materials, such a soiling and discoloration, that might detract from the value of the resource before the end of the useful life of the resource is reached.
In a recent study (NAPAP, 1991), erosion time frames for critical thicknesses of 0.2 cm to 1.0 cm from smooth slabs of marble and limestone under pre-1990 SO2 emission conditions (baseline scenario) were compared to erosion time frames for a 50% reduction in SO2 emissions. For limestone, erosion time frames were generally 10% to 14% longer under the SO2 reduction scenarios than under the baseline scenario. In general, time frames were 200 to 300 years for the 1.0 cm critical thickness assumption, and 40 to 70 years for the 0.2 cm critical thickness assumption. For marble, baseline erosion time frames were longer, ranging from 100 to 600years, and the effects of SO2 reduction scenarios were generally smaller.
These results were based on erosion studies for smooth slabs of Shelburne or Vermont marble, and Salem limestone, and it is not known how applicable they are to other types of carbonate stone, to stone structures with curvilinear surfaces, to structures located in different climates, or to surfaces that have been exposed to weathering processes for long periods of time. There is reason to believe that weathered, curvilinear surfaces are more susceptible to injury than the test slabs: Sherwood and Dolske (1991) report that calcium runoff from marble statues and memorials appeared to be more dependent on shape than marble type. They compared surface recession rates of curvilinear statues to smooth obelisks, and found that erosion rates were 10times greater for curvilinear surfaces than for smooth or flat surfaces.
In summarizing the physical injury in terms of what may be noticeable or pertinent to the consumer, we divide the injury into two general types: chemical alteration and erosion. These are both chemically related processes, but they are distinct in terms of their consumer welfare implications.
In addition, we conclude the following based on the available literature about the reduction in injury expected as a result of the Title IV required emissions reductions:
| 2.5 | Definition of the Good |
After reviewing the literature and developing some descriptions of air pollution injury to marble monuments, we began to design and conduct informal interviews to assess the general public's thoughts and reactions to the importance of monuments and how the value of monuments to the public might be affected by the types of injuries caused by air pollution. There was then an iterative process of developing and testing the basic concepts of the good to be valued for this study and the descriptions used to present the information to a general audience, alternated with feedback from and discussion with the study's expert panel. The following sections of this chapter present the final definition of the good and the valuation scenario developed as a result of this process, with a summary of the rationales for various choices made.
| 2.5.1 | Materials and Resources: Marble Monuments |
Because the nature of the physical injury differs with different kinds of materials, and because the economic value is intricately tied to the function and purpose of the resource, it was necessary to narrow the focus of this project to selected categories of cultural materials and resources. We initially chose monuments made of carbonate stone for the focus of this project because it is a subset of cultural materials under study that is likely to have significant economic damages related to acid rain and its precursors. Two key reasons for this conclusion are:
Cultural resources made of bronze, carbonate stone (e.g., marble and limestone), or mortar are all susceptible to physical injuries caused by exposure to air pollutants. Because these injuries may be reduced under Title IV reductions in SO2 and other acid deposition precursors, we considered studying injury impacts for all of these types of materials. However, we recognized that the amount of information necessary to convey injury information for all three material types would be overwhelming for a single survey. We quickly narrowed our focus to carbonate stone because mitigation strategies for bronze and mortar are relatively effective compared to available strategies for carbonate stone. For bronze structures, regular maintenance and protective coatings can prevent weathering injuries. Repointing, or replacing lost material, can usually fully mitigate injuries to mortar. Conversely, mitigation options for carbonate stone tend either to exacerbate weathering injuries (e.g., cleaning the stone can cause erosion) or to permanently alter appearance (e.g., removing and replacing broken stone blocks). NAPAP's 1990 Integrated Assessment (1991, p. 76) concluded that "[among cultural resources, buildings and monuments made of carbonate stone are the most sensitive to injuries and the least amenable to protective treatments." This suggests that injuries to cultural resources made of carbonate stone may be an important source of damage values, particularly when we are concerned about injuries that cannot be fully mitigated.
We further narrowed our scope to marble monuments. This decision was dictated by several considerations. First, marble and limestone have different injury time frames, which would necessitate independent discussions in a survey context. Second, marble was more commonly used for nationally significant monuments in the eastern United States, which are the category of cultural resources chosen for this study.
For the purposes of the scoping interviews we began to develop a definition of monuments. This definition was influenced by the geographic scope that was ultimately selected for the valuation exercise (see the next section). As we began to focus on the Washington, DC, area and the outdoor marble monuments that would be affected by changes in air quality in the area, we broadened our definition of monuments to include a few historically significant marble buildings with special symbolic meaning including the U.S. Capitol and the Supreme Court buildings. It seemed artificial from the point of view of the public and contrary to the intended valuation exercise to exclude these historic marble buildings, which are recognized as national symbols and often included in a tour of the historic and cultural sights of Washington, DC.
The following definition of a monument was thus developed during the scoping interviews and used in the final survey instrument:
Photographs were also selected to illustrate examples of monuments made of various materials, including a variety of monuments made from marble. The final set of photographs used in the survey is included in Appendix B. We used the people-made adjective to emphasize that we were not including natural national monuments such as Natural Bridges National Monument in Utah.
During the scoping interviews and focus groups, respondents were shown photographs of monuments made of various materials, including marble. Respondents easily distinguished between marble and other materials, and understood the definition of monuments. Most respondents were able to name some monument they had seen, and most had visited at least one monument within the past two years. One of the consistent findings in the scoping interviews with regard to visitation to monuments was that the visit to the monument was seldom the primary purpose of the trip. The important implication of this finding for economic valuation is that values inferred from visitation data (e.g., trip expenditures and behavior) would be deficient for measuring value.
The scoping interviews and focus groups also explored reasons why monuments are valued. The questions distinguished between own use, and use by others now and in the future (altruistic and bequest values), and distinguished between historic and aesthetic interests in the preservation of monuments. Respondents consistently gave the historic and commemorative information conveyed by monuments as the most important reasons for preserving them, and listed visitation by others now and in the future as more important to them than their own visitation. Aesthetic considerations tended to be secondary, but connected to the effectiveness of the monument in its primary purpose of teaching and commemorating. These responses led us to choose a valuation approach that estimates total preservation value rather than approaches that would be confined to estimation of a person's own use value only.
| 2.5.2 | Geographic Scope: Washington, DC |
Most reductions in SO2 emissions as a result of Title IV will occur in the eastern United States. Consequently, the potential benefits to marble monuments will be in that region. We reviewed cultural material inventories to determine if adequate inventories of marble monuments existed, and whether the set of marble monuments in the eastern United States could be easily characterized in a survey. Available information indicates that most of the marble monuments tend to be located near sources of marble in the northeast. We found, however, that inventories of cultural resources are generally incomplete, and there was no easy way to characterize the entire set of marble monuments throughout the eastern United States.
At the same time, we were testing the feasibility of different geographical scopes for the marble monument resource set in our survey. Three possible geographical scopes considered were: (1)all marble monuments in the northeast; (2) a single monument; and (3) a distinct set of marble monuments in a small location. The set of all monuments seemed difficult to describe, particularly in terms of how the preservation program would operate, and the single monument approach seemed too limited and not as useful for the NAPAP assessment if the results could not be easily generalized to other monuments. The third approach seemed the most feasible. Based on focus group results, which indicated that people generally tended to be more interested in the physical condition of nationally significant monuments than local monuments, we selected marble monuments in Washington, DC, as our resource set. We considered the following options:
Our plan to focus on the monuments in Washington, DC was further supported by the finding that in Colorado and in Boston a majority of respondents in each focus group had been to Washington, DC, at least once in their lives, and many had visited within the last five years. This indicates that a large share of the population has some first-hand knowledge and familiarity with these monuments, at least with the well-known ones.
After Washington, DC was selected as the focus of the study, we made a list of outdoor marble monuments in the area, along with a map showing locations of many of the more familiar marble monuments in the area. This list and map gave specific definition to the set of monuments that were the focus of the valuation exercise. A final set of photographs showing examples of the marble monuments in the Washington area was developed. These illustration materials are included in Appendix B.
| 2.5.3 | The Change in the Resource to Be Valued: Reduction in Rate of Future Injury |
The first issues addressed in the scoping effort with regard to injury to marble monuments were how respondents reacted to the type of injury that air pollution causes, and whether they cared about a change in the future condition of the monuments. Although there were some comments that a certain amount of visible aging contributed to the historical message of a monument, most subjects in the scoping effort agreed that deterioration beyond some point is bad and detracts from the intent and purpose of the monument. Reasons given included the following: (1)degradation indicates lack of appreciation or respect for the commemorated event, idea, or person; (2) there is a loss of aesthetic beauty; and (3) dirty, eroded objects become an eyesore.
This issue was explored further by asking respondents how long they thought that marble monuments in Washington, DC should be preserved. The answers indicated that people have fairly long time horizons when it comes to preservation of monuments, especially those of national significance. The interest horizon seemed long enough to encompass the change in the rate in injury expected as a result of the Title IV program.
A key issue for the scoping work was whether and how the injury could be described and still convey the key points in the scientific literature. We developed descriptions of two injury processes, erosion and gypsum formation, and illustrated each with some photographs. We initially referred to gypsum formation as "discoloration" because the macroscopic manifestation is surface discoloration due to trapped soil on the chemically altered surface. However, we found that this did not adequately communicate the permanent nature of the change in the stone surface and later changed the name of this effect to "chemical alteration."
At first, we tried to introduce the injury descriptions without mentioning air pollution, but we found that respondents immediately began discussing air pollution and acid rain as a factor. We then changed the injury description to acknowledge the role of air pollution at the start of the discussion. We used the phase "natural and pollution-related weathering" to refer to the injury process as a whole, acknowledging the often inseparable process of natural and pollution-related effects. Respondents seemed comfortable with this description and did not seek further distinction between natural and pollution-related processes.
The next element in describing the change in the resource was to introduce the time line. In the absence of the Title IV pollution reduction, there is a baseline rate of change in the resource. The pollution reduction means a slowing in the rate of injury. The change that we wish to value is the difference between the rate of injury with the Title IV pollution reduction versus the rate of injury without Title IV. Although there is uncertainty about both the injury rates, plausible time lines were developed in consultation with the expert reviewers for the study. Initially, two baselines and three alternative injury reduction time lines were developed in an attempt to span the uncertainty. Ultimately, the variation was reduced to one baseline with three reduction time lines.
To illustrate injuries over time, two photographs were selected and digitally enhanced to show three levels of injury. One photograph was a marble statue of Ben Franklin and the other was the detail at the top of a column on a building (i.e., a column capital). The first photos in the two series are intended to illustrate the typical current condition of marble monuments in Washington, DC. The second and third photographs illustrated two levels of further deterioration. Copies of these photograph series are included in Appendix B. Figure 2-1 shows where the photographs were placed on a time line that was shown to participants. The actual time line presentation was on a poster board that was large enough for the photos.
Questions that were asked in early focus groups about the photograph series were: "How do they know what will happen in the future?" and "What about ongoing maintenance of the monuments?"To address both questions in later focus groups, we added a statement that these photographs represent the predictions of chemists and experts who have studied these weathering effects, as well asanacknowledgment that these changes represent expected "average" effects. Any individual monument might be more or less changed. We also added some discussion of current maintenance practices, which consist of periodic cleaning of loose soil, including removal of graffiti and bird droppings, and repair of structural weaknesses as needed. We were trying to communicate that this is the baseline if nothing changes from current conditions and maintenance practices. Adding these explanations made the presentation go smoothly.
Large poster boards showing a time line for each preservation option were used to present the different quantities of injury reduction as well as provide a visual comparison to the baseline (Appendix B). An example of one of the time lines is shown in Figure 2-2. The photos used on the boards are the same as those handed to subjects. The same two sets of three photos were positioned on the time lines to illustrate how a preservation option increases the amount of timeit takes injuries to occur. This communicated the important point that none of these programs would completely eliminate the injury; they simply extend the time it takes for the injury to occur.
| 2.5.4 | Valuation Approach: Stated Preference |
Some of the early scoping questions were designed to help us decide what kind of valuation approach to adopt. The key question was whether a visitation-based valuation approach would capture all the benefits. Such revealed preference approaches are often more favorably received because they are based on observed or reported behavior rather than stated or intended behavior.
In the scoping surveys and focus groups of our scoping study, participants were asked to rate several reasons for why monuments were important. We found that, on average, participants tended to rate the importance of reasons related to passive values more highly than those related to direct use values. This finding is consistent with Navrud et al. (1992), which reported that nonuse motivations tended to be more important than concerns about the quality of a person's own visits. Consistently we found that although respondents commented on moving personal experiences when visiting certain monuments, the number one reason they gave for being willing to pay to preserve and maintain these monuments was so that they would be available for others now and in the future. They stressed the historic and inspirational message that monuments convey and the importance of conveying this message to future generations.
These findings led us to conclude that a stated preference approach is preferred because it estimates all benefits including both direct use and passive use. Revealed preference approaches such as travel cost methods would capture only direct use values. Furthermore, they would be difficult to implement because visits to monuments often occurred during trips made for other reasons, which means that travel costs would need to be allocated across destinations or reasons for taking the trips. Finally, the scoping results indicated that a general population survey would provide more comprehensive information than a survey of visitors to the monuments in Washington, because visitors and nonvisitors might have significantly different preservation values.
| 2.5.5 | Hypothetical Mechanism: Preservation Treatment |
To study the economic benefit of reducing air pollution injury to cultural resources, it is necessary to construct a hypothetical mechanism which achieves the reduction and obtains valuation data from the respondent. We decided against positing an air pollution reduction program because respondents would have a difficult time ignoring the other benefits of pollution reduction (e.g., visibility improvements or health benefits) when making valuation decisions. One approach might have been to obtain a value for the Title IV pollution reduction as a whole, and then have respondents attribute a portion of this to the preservation of marble monuments. This approach would have required a lengthy presentation of comprehensive information about the effects of air pollution, an elicitation of values for reducing all of those effects, and finally a method for separating total value into component parts such as benefits to cultural materials. It is possible that the value of reducing injury to marble monuments is a relatively small compared to the total value of reducing air pollution, so this approach was rejected as an ineffective and cumbersome approach to valuing the preservation of outdoor marble monuments.
Instead, we developed a hypothetical preservation program for a specified set of marble monuments that mimic the effects of air pollution reduction by slowing the rate at which injury occurs. During the scoping effort, we tested various preservation programs. These included a chemical coating program, and a program to repair and replace monuments. Focus group participants found the chemical coating treatment program for marble to be credible (even though it does not exist at this time), so we continued to refine the coating program to address concerns such as the whether the coating is nontoxic or harmful to marble. This chemical coating mimics the changes in injury rates that might occur as a result of a change in air pollution, while maintaining a credible focus on the selected set of Washington monuments.
The preservation program has three optional levels of effectiveness, which we call Options A, B, and C. The different effectiveness levels were achieved using different coatings and application techniques. The three options were distinguished by how they affected the injury time line. Option A increased by 25% the amount of time in which the injuries in the photo series occurred, so the injuries shown in the second photo of the photo series occurred in 95 years instead of 75years, and the injuries shown in the third photo of the series occurred in 190 years instead of 150 years. Option B increased the amount of time by 50%; and Option C increased the amount of time by 100%. Table2-1 summarizes how the three preservation options affect the injury time line.
1. Free-riding behavior is when respondents do have value for the good or service, but say they are not willing to pay for it because they assume others will pay for it and they will be able to enjoy the benefits without themselves having to pay.
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