Parents of children at a south Dublin national school are protesting against plans by Vodafone to erect three telecom antennas on a roof next door.
Students and parents from Monkstown Educate Together National School have received the backing of singer Christy Moore for their campaign.
They say the 438 students, along with teachers and other staff, will be subjected to radiation throughout the day if the mast gets the go-ahead.
Dun Laoghaire-Rathdown Co Council granted permission in January for the mast to be installed on the roof of the Institute of Art, Design and Technology building next door.
However, that permission has been appealed to An Bord Pleanala, with a decision due on June 20. Opponents of the mast gathered yesterday to call for the plan to be scrapped.
Among the allegations are that Vodafone did not identify the school on maps it originally submitted in making the planning application and did not consult the school.
The protesters have claimed the beam of maximum intensity from the antennas will affect the school.
"Vodafone applied for planning during last year's summer holidays," said protest group spokesman Brian Healy.
"Its initial application map omitted our school, which fell within the beam of maximum intensity and is located right beside this proposed mast.
"Research points to the dangers of locating a mast next to vulnerable children under the age of 12, whose brains haven't developed properly.
"Furthermore, no meaningful consultation was made with the school during this process."
Christy Moore said that "just because it was legal didn't mean it was right".
"Shame on Vodafone, Shame on IADT," he added.
Telecoms watchdog, ComReg, last year reassured people that radiation levels from mobile phone masts were safe.
A statement from Vodafone said it was awaiting the An Bord Pleanala appeal.
"Vodafone has complied with all planning and regulatory obligations in terms of this application," it added.
IADT refused to comment on the protests but said that "health and safety is and has been of prime importance to the institute in considering the proposal".