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Impact of power transmission lines on property values: a case study.

Studies have been conducted in an attempt to link electromagnetic radiation to some forms of cancer and other health risks. Each study has produced differing levels of evidence as to the validity of this theory. This research project endeavors to analyze the impact of power transmission lines on residential property values and the marketability of real estate in Memphis and Shelby County, Tennessee. Public knowledge of a possible connection between electromagnetic radiation and health risks such as cancer would probably have a profound effect on the real estate market for homes located in close proximity to power transmission lines.

The purchase of a home is often the biggest single investment a person will ever make. This is not an investment that is taken lightly, and any homeowner wants to protect the value and future benefits of ownership.(1) Regular maintenance, landscaping, and home additions can protect and enhance the value of property. External factors, however, such as the presence of adverse conditions or features adjacent to property that are beyond a homeowner's control can and do affect property values.(2) Examples of adverse external factors are dumps, landfills, factories that produce noise and bad odors, neighbors who allow their property to deteriorate, and of course power transmission lines.

There are two ways in which power transmission lines may adversely affect property value or marketability. The first is the mere presence of the transmission towers, which create an eyesore, as well as easements and encroachments on properties. The second, somewhat latent, is not as widely known. Since the late 1970s, studies have been conducted to attempt to determine whether there is any connection between electromagnetic radiation emitted by power transmission lines and possible health hazards such as cancer.[3] The presence of these possible health hazards, if known to the general public, could certainly lead to a decrease in demand for properties located near transmission lines and in turn lower property values in these areas.


The cornerstone study of electromagnetic fields (EMFs) and their connection with health hazards was conducted in the 1970s by Nancy Wertheimer and Ed Leeper in Denver, Colorado.[4] In their study, Wertheimer and Leeper compared the EMF exposure of 344 children who died of cancer over a 23-year period from 1950 to 1973 with those of an equal number of children who did not get cancer born at approximately the same time as the cancer victims. Wertheimer and Leeper concluded that the children who lived in high-exposure homes (i.e., homes in close proximity to the power transmission lines) were two to three times more likely to contract some form of cancer, particularly leukemia, lymphomas, and nervous system tumors, than were the children who lived in lower exposure homes (i.e., homes not in close proximity to power transmission lines).

The results of this study were greeted with both skepticism and heightened interest in the research community. Skeptics agreed that too many assumptions were made as to the intensities of EMFs, and that actual measurements were not made. Nonetheless, the results led to more studies that used better control measures.

One such study was conducted in the Denver metropolitan area by David A. Savitz.[5] Savitz's goal was to replicate the study of Wertheimer and Leeper using more controlled measures and a greater level of thoroughness. It was generally thought that this study would disprove the results of Wertheimer and Leeper. It merely improved and refined them, however, giving greater weight to the evidence that there may be some connection between exposure to EMFs and some forms of cancer.[6]

Other studies were expanded to include electromagnetic radiation emitted from household appliances such as hairdryers and electric blankets.[7] Still another study, conducted in England, produced evidence that persons living or working near electromagnetic fields are subject to more depression and a greater incidence of suicide.[8]

Research conducted by Kavet and Banks indicated that EMFs do have some effects on cell membranes and tissues.[9] The biological responses in vitro are sensitive, not only to the magnitude of the radiation, but also to the waveshape and frequency of the radiation. On the other hand, studies on animals and humans are inconclusive. They fail to produce results comparable with the cell results and attest to the need for more research.[10]

In general, while all of the previously noted studies manifest varying levels of health hazards in relation to electromagnetic fields (as a result of differences in control groups and measures as well as techniques), they all suggest that there is some evidence to support a link between electromagnetic fields and health problems such as cancer.


The study discussed in this article was an attempt to analyze the spatial relationships between power transmission lines and property values in Memphis and Shelby County, Tennessee. Using power line maps available from Memphis Light, Gas, and Water (MLGW), neighborhoods transected by high tension lines were identified. Once these areas had been identified, individual homes directly under or adjacent to these power lines were surveyed to collect data on real or perceived influences on the property's value or marketability. This survey addressed both the issue of possible health hazards and the negative aesthetic impact of power lines.

Information was gathered concerning any differences between prices paid for homes directly under or adjacent to power tranmission lines, and prices paid for homes in the same neighborhoods but located further away from the power transmission lines. The data were gathered from recognized local real estate services (e.g., Chandler and Chandler Residential Report, Memphis Association of Realtors Multiple Listing System), and used comparable types of housing as they could be located.

All data obtained through surveys, research, and personal observations were used to formulate a computerized map to show the spatial distribution of residential houses adjacent to transmission power lines as well as a computerized database (i.e., attribute data file) for the residential real estate property, called a Geographic Information System (GIS). Included in the database for the GIS are locations, distance to transmission power lines, square footage, type of housing, and information listed in the current Multiple Listing System (MLS) near the power lines. The database established by using the GIS can easily be updated.

In addition to the database construction of residential real estate value affected by power lines, a questionnaire was developed to survey homeowners who lived in houses directly adjacent to the power transmission lines. The responses to the following questions were used to determine the amount of influence the presence of power lines has on value.

1. When you purchased your home, did you consider the close proximity of the power lines and towers as a negative influence either as an eyesore (aesthetic negative) or as a potential health hazard?

2. If so, did either factor influence the price you were willing to pay for your home?

3. There is some evidence that these types of power lines and the electromagnetic radiation they emitted may cause some forms of cancer. Were you aware of this when you purchased your home?

4. If you had been aware of such evidence (i.e., the possibility of a link between the electromagnetic field emissions from power lines and some cancers) would it have adversely affected the price you would have been willing to pay for your home? or

Would this information have caused you to look elsewhere for comparable housing distant from power transmission lines?

5. Do you think that if this information about the possible link between power lines and their electromagnetic fields to cancers was more widely publicized that the market for homes located near such power lines likely would decline?

The results of this questionnaire were compiled, analyzed, and reconciled along with market information into a summary and conclusion.[11]


The results of the survey provide the basic information in this discussion. Of 80 homeowners in 2 adjacent neighborhoods in east Memphis and Shelby County who were polled, 47 complete responses were received and analyzed. In response to question 1, 25 homeowners (53%) said that they consider the presence of the transmission lines and towers an eyesore, while 22 (47%) did not. In response to the second half of the question, no homeowners considered the presence of the transmission lines and towers as possible health hazard. In other words, every single homeowner who responded said they did not consider the transmission lines or towers a health hazard.

Of the 25 affirmative responses to question 2, 7 homeowners (28%) said that the presence of transmission lines and towers affected the price they were willing to pay for their homes. The presence of transmission lines and towers did not affect the price 18 homeowners (72%) were willing to pay, however.

Some interesting and enlightening responses were received to questions 3 and 4. Of the 47 homeowners surveyed, none had any knowledge of the possible evidence connecting power transmission lines to certain health risks such as cancer. This led to question 4 and some predictable responses. If these homeowners had been aware of the potential health risks associated with the presence of the electromagnetic fields emitted by transmission lines, 41 (87%) said that the price they had been willing to pay for their home would have been adversely affected or they would have looked in other areas for comparable housing. For two respondents (4%), access to such information might have had an influence on the price paid for their home or where they were willing to buy a home. Only one respondent would not have changed either the price paid for the home or the location of the home as a consequence of such information.

The last question posed in the survey was an opinion question. In light of the information concerning the connection between the electromagnetic fields of power transmission mission lines to possible health risks such as cancer, what did the home-owners think would happen to the market for homes located in close proximity to power transmission lines if this information were widely publicized and known to the general public? Forty-three respondents (91%) said that they thought the market for these homes would decline, while one said that it would have no effect on the market for these homes.

An attempt was also made to gather information concerning any difference in prices paid for homes directly adjacent to power transmission lines and prices paid for homes in the same neighborhoods but further from the power transmission lines. Information was extracted from the subject neighborhoods using up-to-date sources (1989-1990 Chandler & Chandler residential reports), and using comparable housing as located.

In neighborhood A, two subject properties (i.e., properties adjacent to the power transmission lines) sold for $54,759 ($46.28 per square foot) and $55,350 ($49.64 per square foot), respectively. These prices fall in line with three comparable properties (i.e., properties of approximately the same age, size, and quality, located in the same neighborhood but not directly adjacent to the power transmission lines). These three properties sold for $56,900 ($44.66 per square foot), $55,500 ($51.48 per square foot), and $53,500 ($48.28 per square foot), respectively. The average price of the subject homes, $55,054 ($47.96 per square foot) compares favorably with the comparable homes, with an average price of $55,300 $48.14 per square foot).

In neighborhood B, two subject properties sold for $67,000 ($54.96 per square foot) and $65,000 ($53.32 per square foot), respectively. These prices are in line with four comparable properties, which sold for $68,500 ($53.64 per square foot), $66,685 ($56.51 per square foot), $67,500 ($55.19 per square foot), and $65,500 ($51.65 per square foot), respectively. The average price of the subject homes was $66,000 ($54.14 per square foot) and again compares favorably with the comparable homes average of $67,046 ($54.25 per square foot).

Any slight difference in total price or price per square foot between the subject homes and the comparable homes should be attributed to differences in property condition, style, or buyer preference and seller motivation. This is supported by a comparison of select groups of only comparable properties and the resultant similar slight price differences. These differences are common in any real estate market.


Although there is evidence that the electromagnetic fields emitted from power transmission lines may cause some forms of cancer and that the presence of power lines and towers are an eyesore, these results reveal that the public in general is only aware of the latter. While survey results indicate little knowledge of potential health risks, they indicate a high degree of opinion change once informed about such evidence.

Market evidence further supports the fact that there is a lack of public knowledge about any health risks associated with power transmission lines because no measurable price differences could be detected between homes located adjacent to power transmission lines and comparable homes located further away.

More research needs to be conducted in the area of electromagnetic fields and their connection to health risks. The results must be more widely disseminated to the general public. Further, development in the future clearly should be restricted in the vicinity of power lines and should be kept a significant distance from power transmission lines and towers.[1]

[1.] American Inst. of Real Estate Appraisers, The Appraisal of Real Estate, 9th ed. (Chicago: American Inst. of Real Estate Appraisers, 1987), 35-41.

[2.] Ibid.

[3.] Robert Pool, "Is There an EMF-Cancer Connection?" Science, v. 249 (September 1990): 1096-1098.

[4.] Ibid.

[5.] David A. Savitz and Debra L. Zuckerman, "Childhood Cancer in the Denver Metropolitan Area 1976-1983," Cancer, v. 59 (1987): 1539-1542.

[6.] Pool, 1096-1098.

[7.] David A. Savitz, Esther M. John, and Robert C. Kleckner, "Magnetic Field Exposure from Electric Appliances and Childhood Cancer," American Journal of Epidemiology, v. 131, no. 5 (1990): 763-773.

[8.] Stephen F. Perry, "Environmental Power-Frequency Magnetic Fields and Suicide," Health Physics, v. 41 (August 1981): 267-277.

[9.] Robert I. Kavet and Robert S. Banks, "Emerging Issues in Extremely Low-Frequency Electric and Magnetic Field Health Research," Environmental Research, v. 39 (1986): 386-404.

[10.] Maria A. Stuchly, "Human Exposure to Static and Time-Varying Magnetic Fields," Health Physics, v. 51, no. 2 (1986): 215-225.

[11.] K William Chandler, Chandler and Chandler Residential Sales Report, Memphis and Shelby County Homes, Duplexes, Condominiums, and Lots (1989 and 1990).

[12.] Hsiang-te Kung and Paul M. Barelski, "Environmental Effects of Electromagnetic Radiation from Power Lines," unpublished paper, 1990.
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Author:Kung, Hsiang-te; Seagle, Charles F.
Publication:Appraisal Journal
Date:Jul 1, 1992
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