A Sebastopol group that has fought to limit public exposure to radio waves is suing the city for approving additional antennas to an existing telecommunications tower behind City Hall.

The suit, brought by the EMF Safety Network, claims that the radio wave frequencies emitted by the new antennas will cause "immediate, severe and irreparable harm to the environment."

The group seeks an injunction preventing Verizon and Crown Castle, an international wireless infrastructure firm, from doing the installation work. The suit also demands that the city's approval of the project in December be voided.

"They're not doing their job to protect public and environmental safety," EMF Safety Network founder Sandi Maurer said of Sebastopol's city leaders. "We are forced into doing it."

The safety network has fought PG&E's SmartMeters, downtown Sebastopol Wi-Fi and cellphone antennas.

The group fears that radio frequencies used to transmit data from SmartMeters, as well as electronic emissions from laptops, cell phones, TVs and other devices, can cause "electrical sensitivity" and health problems ranging from chronic fatigue, headaches and insomnia to heart ailments and cancer.

However, the group's lawsuit, filed in Sonoma County Superior Court, focuses on environmental concerns, and in particular, fears that the radio waves emitted by additional antennas at City Hall pose a threat to the wildlife, plants and fish of the Laguna de Santa Rosa, a wetlands that has been proclaimed as having international significance.

Federal telecommunications law allows jurisdictions to consider the environmental impacts of radio waves but not health issues, so long as the emissions fall within FCC guidelines.

The city of Sebastopol claimed that work on the 106-foot tower is exempt from the California Environmental Quality Act because the changes are negligible.

The tower was erected in 1996 and includes both television and cellphone communications antennas. The new work calls for three additional antenna panels for Verizon to improve its cellphone coverage and ability to push more data to such devices as smartphones and tablets.

On Dec. 6, the City Council voted 2-2 to deny the safety network's appeal of the Planning Commission's approval of the project. The tie resulted in a green light for Verizon and Crown Castle.

Representatives of Crown Castle did not return a message seeking comment.

Mayor Guy Wilson, who voted to deny the safety network's appeal, said Monday that he stands behind his vote.

"I don't see an environmental risk," he said. "I realize the EMF sees it differently. I respect that."

You can reach Staff Writer Derek Moore at 521-5336 or derek.moore@pressdemocrat.com.