Health Impacts

I.    The Potential Health Impacts of Wind Turbines- Ontario

In May of 2010, the Chief Medical Officer of Health of Ontario, Dr. Arlene King, prepared a report responding to health concerns related to sound emitted from wind turbines and several other health concerns. This report is organized into sections regarding sound and noise, low frequency sound, infrasound, and vibration, other potential health hazards, and wind turbine regulation.

Sound and Noise

Sound pressure level (loudness) and frequency (pitch) are what characterize sound. The standard measurements for these are decibels (dB) and Hertz (Hz). Each person perceives sound pressure levels differently, but generally human ears can hear sound between 20Hz and 20,000Hz. Frequencies below 200Hz are referred to as low frequency sound and frequencies below 20Hz are referred to as infrasound. Noise is generally defined as unwanted sound.

Wind turbines generate sound through both mechanical and aerodynamic mechanisms. The main source of noise is from aerodynamic sources, however, design and wind speed play a large role in sound level. The “swishing” sound that is characteristic of wind turbines is created by the aerodynamic noise, which is present at all frequencies. The impact of sound on health is directly related to its pressure level. Setback requirements in Ontario are in place to keep noise levels in residences to 40dB or less, which is comparable to indoor background sound and is low enough as to not disrupt health or sleep.

Surveys taken in Sweden and the Netherlands found that there is a strong correlation between the individual’s perceptions of wind turbines and their level of annoyance. Wind turbine noise was also perceived as more irritating than other noises at comparable levels, most likely because of the “swishing” quality.

Low Frequency Sound, Infrasound, and Vibration

Low frequency sound and infrasound are emitted everywhere in the environment, from both natural sources such as wind and rivers and artificial sources like traffic. Although these sounds can be irritating, they are not shown to have any adverse effects on health under 90dB. Wind turbines are thought to be in the 50 to 70 dB range.

It has been proposed that a “whole body system pathology” named vibro-acoustic disease may occur in individuals living near wind turbines after extended periods of time, but this research has not been approved by medical and scientific communities.

One issue is that there is no standard on how to measure noise from wind turbines.

Other Potential Health Hazards of Wind Turbines

EMF’s (electromagnetic fields) are only found in low levels near wind farms and are not a health concern. Shadow Flicker happens when turbine blades rotate in sunny conditions creating moving shadows. It has been suggested to be a problem for people suffering from epilepsy. However, flicker frequencies occur at too slow of a rate to be a problem. Ice throw and ice shed may pose a potential risk to human safety, mainly to personnel near the wind farm. To reduce the risk of injury turbines can be stopped in inclement weather conditions. Structural hazards do occur with turbine blades. However, blade failure is slim and most injuries from wind turbines occur during construction and maintenance.

Setbacks and Community Consultation (for Ontario)

Wind turbine minimum setbacks are set at 550 meters from a receptor. This is affected by the number of turbines to limit sound to 40dB in residences. Before a wind turbine may be constructed, notices must be posted in local newspapers and all land owners within 120 meters and any Aboriginal communities must be notified in preliminary stages of planning. Two community consultations must occur as well as making required studies publicly available. This will be followed up by consultations with local municipalities and with a Consultation Report describing the reception of the proposal.

King, A. Ontario Government Ministries, Ministry of Health and Long-Term care. (2010). The potential health impact of wind turbines (Catalogue No. 014894). Retrieved from: http://www.health.gov.on.ca/en/public/publications/ministry_reports/wind_turbine/wind_turbine.pdf