Cork and Meath residents opposed to the Environmental Protection Agency's decisions to grant draft licences for incinerators in Ringaskiddy and Duleek demonstrated outside the Dáil yesterday.
They said they would continue to fight the proposed incinerators by every means open to them.
They will make submissions to the EPA and seek oral hearings into the decisions.
They also said they would continue with separate High Court proceedings challenging the granting of planning permission by An Bord Pleanála for the two incinerator projects.
They are hopeful their campaign will lead to the EPA deciding to hold oral hearings into the granting of the licences.
Mr Pat O'Brien, a spokesman for the No Incineration Alliance, which opposes the Duleek project, said residents were not satisfied that the EPA had considered fully the facility's health and environmental impacts.
"We've no confidence that the EPA has the manpower or financial resources to police current industries, never mind new developments such as incinerators. There is a real danger that the EPA will examine the issue and attach all kinds of conditions to the licences and then not enforce those conditions."
While the Carranstown, Duleek, proposal was for a facility that would handle 150,000 tonnes per year, residents feared a second and third phase would be built.
"The incinerator may then start taking hazardous waste rather than just household waste as is planned at the moment."
While Carranstown was envisaged to take only waste from counties Louth, Meath, Cavan and Monaghan, he said the group feared that this might, in time, be expanded to include Dublin and other counties.
Any incinerator on the site would result in emissions into the air and water table, he said. It would produce thousands of tonnes of ash per year, even though the Republic had no landfill facility into which the ash could be disposed.
Ms Linda Fitzpatrick of the Cork Harbour Alliance for a Safe Environment (CHASE), which opposes the Ringaskiddy development, said the Government should concentrate on waste reduction and recycling.
"Incineration should be the very last resort. The Government is obviously always trying to attract new businesses and industries to Ireland but one attraction should not be a facility for companies to be less clean than they can possibly be."
CHASE said there had been over 30,000 planning objections to the Ringaskiddy project.
The incinerator was "contrary to the Cork County Development Plan, contrary to the Cork Area Strategic Plan", and was "below the standard recommended by the Basle Convention for disposing of solid hazardous waste".
Cork South Central Green Party TD, Mr Dan Boyle, strongly criticised the manner in which details of the announcement of the draft licences were leaked to the media.
