Better Plan, Wisconsin

This important document prepared by Dr. Carl V. Phillips MPP, PhD, was submitted to the Wisconsin Public Service Commission as testimony on whether turbine noise is having an adverse effect on human health.

Executive Summary

A summary of the main conclusions of my expert opinion, based on my knowledge of epidemiology and scientific methods, and my reading of the available studies and reports, is as follows:

• There is ample scientific evidence to conclude that wind turbines cause serious health problems for some people living nearby. Some of the most compelling evidence in support of this has been somewhat overlooked in previous analyses, including that the existing evidence fits what is known as the case-crossover study design, one of the most useful studies in  epidemiology, and the revealed preference (observed behavior) data of people leaving their homes, etc., which provides objective measures of what would otherwise be subjective phenomena. In general, this is an exposure-disease combination where causation can be inferred from a smaller number of less formal observations than is possible for cases such as chemical exposure and cancer risk.

• The reported health effects, including insomnia, loss of concentration, anxiety, and general psychological distress are as real as physical ailments, and are part of accepted modern definitions of individual and public health. While such ailments are sometimes more difficult to study, they probably account for more of the total burden of morbidity in Western countries than do strictly physical diseases. It is true that there is no bright line between these diseases and less intense similar problems that would not usually be called a disease, this is a case for taking the less intense versions of the problems more seriously in making policy decisions, not to ignore the serious diseases.

• Existing evidence is not sufficient to make several important quantifications, including what portion of the population is susceptible to the health effects from particular exposures, how much total health impact wind turbines have, and the magnitude of exposure needed to cause substantial risk of important health effects. However, these are questions that could be answered if some resources were devoted to finding the answer. It is not necessary to proceed with siting so that more data can accumulate, since there is enough data now if it were gathered and analyzed.

• The reports that claim that there is no evidence of health effects are based on a very simplistic understanding of epidemiology and self-serving definitions of what does not count as evidence. Though those reports probably seem convincing prima facie, they do not represent proper scientific reasoning, and in some cases the conclusions of those reports do not even match their own analysis.

Important editor's note: The last page of Dr. Phillips document, which contained references to his work, was omitted. He has provided us with the missing information as follows:

Roberts M, Roberts J. Evaluation of the scientific literature on the health effects associated with wind turbines and low frequency sound.  Exponent Inc.  Prepared for Wisconsin Public Service Commission Docket No. 6630-CE-302 (the identity of the actual client for whom this was prepared is not disclosed in the document). October 2009.

Waye K. Effects of low-frequency noise on sleep. Noise and Health 6(23):87-91, 2004.

Dr. Phillips will post any other errata at this link as the need arises.

This report, prepared by Acoustics and Noise Control expert Richard D. Horonjeff, explains how turbine noise differs from other types of noises within a community. The information was submitted to the Wisconsin Public Service Commission. An excerpt of the report is provided below. The full report can be accessed by clicking on one of the links at the bottom of this page.

The nature of wind turbine noise compared with other noise sources heard in residential communities

Different sound sources vary in their sound level, frequency content and temporal character. These differences are most easily described by example. First, there are steady state noise sources. A good example would be an active highway. The sound level at a listener location away from the highway may vary somewhat from moment to moment, but by small amounts. But by and large human observers perceive highway sound as near constant in amplitude.

Second, there are transient sources. These are sources present only for brief periods of time. Good examples are passing trains or aircraft. These sources rise gradually in amplitude as they approach the listener and then decay as they depart.

A third class of sound source is the impulsive one. These sources can be repetitive or random in nature. Repetitive impulse sources would be jackhammers and pile drivers. The basic difference between the two examples is the rate at which the impulses occur. A random impulsive source would be the operations in a machine shop where hammering or metal fabrication takes place. In all of these examples any one impulse lasts for only a very small fraction of a second, and the onset and offset of the impulse is very rapid.

Finally, we come to the wind turbine source. Unlike any of the previous sources described, it is neither steady state in the classic sense, nor is it transient, nor is it impulsive. Instead, it produces a distinctive broadband "swoosh-boom" sound4 with each passing blade of the turbine. Each whoosh effectively modulates the sound level, with a more gradual onset than an impulsive sound, and a less gradual one than the transient sources I mentioned. For the typical three-bladed turbine in the 1-megawatt output range the blade passage rate is nominally one per second. One can sound out the observed sound in the typical second-counting style... "whoosh" one thousand, "whoosh" two thousand, "whoosh" three thousand, and so on. So long as the wind is blowing at sufficient speed to drive the turbine the sound will be generate for lengthy periods of time without interruption.

The hours of operation of wind turbines are not dictated by diurnal patterns of human activity like many other anthropogenic sources. They are able to operate when wind conditions are favorable, day or night. This means they may become a factor during both waking and sleeping hours.

The repetitive sound character is unique and unlike any other source found in residential communities. As such it is easily identifiable. It does not blend in to other background sources that are continuous in nature.

Wind turbine noise is most prevalent in rural areas. By their very nature, large-scale wind turbine installations require vast areas of open land. Hence, any potential sound masking effect from urban and suburban sources is unlikely to be present. This means that their sound will be audible at lower levels in the rural environment. It further means that rural noise standards should be applied to these installations as opposed to suburban or urban ones where nighttime sound levels, for example, can be 15 to 20 decibels higher.

Web link: http://www.bccrwe.com/images/stories/videos/Horoje...