Detractors leveled dramatic charges against wind turbines and their proponents Thursday at a hearing on new sound rules for the structures, alleging the turbines cause heart illness and accusing the Public Service Board of endangering the public with too-lax protections for neighbors.
The accusations came during a hearing for new sound limits that will apply to wind turbines, potentially restricting them to produce no more than 39 decibels at night, and 42 during the day, as measured outside the homes of nearby residents.
Wind power supporters say that the standards are too restrictive, and that they’ll prevent future wind energy development in the state. Some wind power opponents say the rules are a worthwhile improvement over the current 45-decibel outdoor sound limit; others say the turbines still pose grave dangers to Vermonters who live nearby.
Lawmakers said they intend to hold at least one more hearing on the rules before taking action on them.
Public Service Board members told lawmakers that the rules are meant to limit the annoyance neighbors might experience from hearing the turbines, and to protect against unspecified health risks.
The Vermont Department of Health has found that no credible evidence links wind turbines and adverse health effects. The Canadian government arrived at a similar conclusion after a two-year study, as did Massachusetts and others.
Legislators took testimony Thursday from a woman who rebutted those findings.
“The health effects we have seen [from turbines] are very serious — they include cardiac issues,” said Annette Smith, executive director of a group that fights wind projects called Vermonters for a Clean Environment.
Smith told legislators that health harms from the sound produced by wind turbines are “well documented.”
Critics also voiced concern about “infrasound,” described as having a frequency below what’s typically considered the threshold of human hearing, around 20 hertz, and said the board had ignored warnings about their health effects.
A 2001 literature review by the National Institute of Environmental Health Sciences cited studies showing swimming produces infrasound pressures in swimmers’ ears of up to 140 decibels, and running produces infrasound at volumes up to 90 decibels. Driving exposes automobiles’ occupants to infrasound levels of up to 120 decibels. A washing machine’s spin cycle emits around 80 decibels of infrasound.
Olivia Campbell Andersen, executive director of the industry group Renewable Energy Vermont, told the committee that PSB members went too far in restricting wind turbines’ sound volumes to 39 decibels, in the absence of credible evidence for health risks associated with wind turbines.
The 39-decibel nighttime sound limit threatens the viability of future wind projects, Campbell Andersen said, and both legislators and the overwhelming majority of more than 700 Vermonters who commented on the rules want more wind turbines in the state.
Furthermore, Campbell Andersen said, the Public Service Board did not supply with the rules any citations that justify the 39-decibel nighttime sound limit as a protection from either health effects or annoyance.
That number was at least in part the result of a judgment call, said board member Sarah Hofmann.
The PSB has in the past assigned a sound limit of 45 decibels to wind turbines, as measured outside the homes of nearby residents, and the level of sound produced by existing Vermont wind turbines has annoyed some neighbors of the projects, Hofmann said.
But the figure was also based on standards established by the World Health Organization, said Tom Knauer, a PSB utilities analyst.
The WHO recommends that sleeping people be exposed to no more than 30 decibels at night in order to rest soundly, and board members reasoned that sound originating outside a home diminishes by about nine decibels when it penetrates the home’s exterior, Knauer said.
Smith contended that margin is too large, especially in the summertime when windows are open.
The hearing took place before the Legislative Committee on Administrative Rules, a body of eight legislators who review proposed rules to ensure, among other things, that the rules accomplish what legislators intended.
LCAR members said they’re likely to take up the rules again at their next meeting, scheduled for June 22. The committee may approve the rules or send them back to the Public Service Board for revision.