Meath County Council has granted planning permission to Indaver Ireland for an incinerator as part of a £60 million waste management facility at Carranstown, Duleek, four miles from Drogheda.
The permission is subject to 30 conditions including limitations on the volume of waste, and a requirement that it treats only waste from the north-east.
More than 4,000 individual objections and a petition with more than 27,000 signatures had been lodged with the county council by opponents of the plan.
The planning decision has been branded "appalling"' by a spokesman for the No Incineration Alliance. "Whether there are conditions or not, it must be one of the worst planning decisions ever made in Co Meath," he said.
"It is appalling that the council would see fit to grant the go ahead for what is in effect a cancer factory close to a primary school at Mount Hanover, within miles of the centre of Drogheda and so close to the developing residential area of east Meath."
A local action group, The Louth Meath Anti-Incineration Alliance, said the plant would pose a serious health risk to 100,000 people living along the Drogheda east coast to Balbriggan by releasing cancer-causing dioxins into the atmosphere. The objectors also believe the transport of toxic ash from the plant would pose a threat.
Indaver has rejected these concerns as unfounded and said that 50 per cent of the cost would be spent on guaranteeing the plant operates below EU emission limits.
Once the alliance has studied the conditions attached to the permission, it will begin preparing a detailed case for an Bord Pleanala.
The incinerator will generate enough electricity to power 16,000 homes, according to the company.