The health effects of wind turbine infrasound based on its propagation on the people in the surroundings of wind turbines in Finland: Statistical analysis
Mehtätalo, E., M.Sc. (Agric. and For.)
Mehtätalo, M., M.Sc. (Agric. and For.)
Peltoniemi, P., M.A. (Phil.)
The purpose of the pilot study was to find out the effects of wind turbine infrasound on the health of the people in the surroundings of wind turbines. The material of the study was collected in Satakunta and Northern Ostrobotnia in Finland (see Figure 1) in spring 2016.
The study was sampled from two (2) different registers by simple random sampling. One register was the customer register of a company in Northern Ostrobotnia, the other was a register of members of an association in Satakunta. An interview method was used as a method for collecting research material. A total of 193 people from 46 families participated in the survey. They came from areas where the wind turbines had been built and started 0.5–3 years before the interview. As the limit of the exposure time was kept three years, and no family with a longer exposure time was accepted to the sample of the study. The distance of each family to the nearest wind turbine(s) as well as the building and starting time of the wind turbine(s) were found out for the interview. Some of the interviewees lived near wind turbines, some at a distance of tens of kilometers.
In addition to that, a map model was developed to describe the exposure zones, in other words the propagation, continuity and magnitude of the wind turbine infrasound, on a map of Finland (see Figure 1).
Figure 1. The area in Northern Ostrobotnia is located in the south of Oulu Province in Finland. The wind turbine infrasound is almost continuous in the yellow-bounded area (the zone 1 in the map model).
As the statistical method of the study was used the linear mixed model to test the statistical significance of the research material. The symptoms of the people were explained either by the direct distance (km) to the nearest wind turbine or by the exposure zone of the map model. Other explanatory variables included the register used, the gender and age of the person and his or her awareness in advance of potential harmful health effects from wind turbines.
The distance less than 15 kilometers from wind turbines was divided in four (4) distance classes for a visual observation. The differences in answers between them were small and varied clearly only in the next class where the distance to the nearest wind turbine was more than 15 kilometers (see Figure 2). The harmful or severe symptoms were clearly more common less than or about 15 kilometers from wind turbines than further away.
Figure 2. Symptoms according to the direct distance less than or about 15 kilometers to the nearest wind turbine and further away, more than 15 kilometers to wind turbines.
The map model included three (3) different exposure zones (see Figure 3). In the first zone nearest wind turbines there was quite strong infrasound in all wind directions. In the second zone there was wind turbine infrasound often, due to the wind directions. In the third zone there was almost no wind turbine infrasound according to the computational model. The map model explained symptoms better than the direct distance to the nearest wind turbine.
Figure 3. Symptoms of almost continuous or often persistent infrasound exposure in the exposure zones of the map model (less or about 15 km from wind turbines and further, more than 15–20 km from wind turbines).
There was no significant p-value for the damage increasing directly according to the distance (km) in the statistical analysis. The significant p-value was reached for the damage according to the map model describing the total exposure. In addition to that, symptoms were explained by person’s gender and age. Other background variables did not explain the symptoms statistically significantly.
The most typical symptoms were sleep disturbance or change in the need for night’s sleep, fatigue and various pains.
The results of the study show that there were remarkably more harmful health effects caused by the wind turbine infrasound in the exposure zones 1–2 of the map model than further away. The most important result of this study is that the risk distance grows if the height, amount or efficiency of the wind turbines increases or with time in a long-term exposure. This means that the risk distance depends on the circumstances. In the areas with wind turbines around the residental area there were harmful health effects as far as about 15–20 kilometers from wind turbines under the circumstances when this pilot study was conducted.
Thus, the potential damage should be investigated within a sufficiently long radius of the wind turbines, taking into account all wind turbines in the vicinity as well as the most typical wind directions. This study confirms the results of a long-term study of Ceranna and Pilger (2004–2016) about the propagation of the wind turbine infrasound.
Deutsch: Die gesundheitlichen Auswirkungen von Infraschall emittiert durch Windenergieanlagen auf die Anwohner in der Umgebung von WEA in Finnland, basierend auf der SchallausbreitungStatistische Analyse
Additional information: Suomen ympäristöterveys ry [Finnish Association for Environmental Health]
Infrasound causes harmful health effects as far as 15-20 km from wind turbines — The risk distance grows if the efficiency, amount or height of the wind turbines increases or in a long-term exposure
—Finnish: Infraääni aiheuttaa terveyshaittoja jopa 15-20 km:n etäisyydellä tuulivoimaloista
The propagation area of infrasound from wind turbines has expanded quickly in Finland in 2016-2017
—Finnish: Tuulivoimaloiden infraäänen leviämisalue on laajentunut nopeasti Suomessa vuosina 2016-2017
Pilot study shows no significant reduction in damage caused by infrasound until more than 15 kilometers from wind farms
—Finnish: Pilottitutkimus osoittaa infraäänihaitan vähenevän merkittävästi vasta yli 15 kilometrin päässä tuulivoimaloista
—German: Die Pilotstudie zeigt eine signifikante Verringerung der Symtome von den Infraschallemissionen erst in über 15 Kilometer Entfernung von Windkraftanlagen