BANGOR — Maine’s Board of Environmental Protection today tweaked proposed rules aimed at reducing noise produced by wind turbines, and will take public comment on them until Aug. 29 before deciding whether to adopt the changes.

Recommendations that had been proposed to the board by the state Department of Environmental Protection would allow turbines to produce up to 55 decibels during the day, and either 45 or 42 decibels at night. The board kept the 55 decibel daytime standard but chose the 42-decibel nighttime alternative, while making other technical changes including provisions in the complaint response process.

Activists have insisted that poorly sited wind farms threaten the state’s public health and natural beauty. The Bangor Daily News says the Friends of Maine’s Mountains group believes a 35-decibel nighttime level is more appropriate.

Until now, the DEP has applied a decades-old noise standard to wind energy projects. Critics of large-scale wind projects say the state needs rules specific to the unique characteristics of wind turbines. After gathering enough petition signatures, Friends of Maine’s Mountains filed paperwork to force the board to begin the rule-making process to address wind turbine noise.

Nearly 200 wind turbines operate in Maine, and many more are in the permitting process.

The rules are to be posted on the DEP’s website.