An incinerator at Barry docks has been given the go-ahead to operate after a long-running battle.
Biomass UK No.2 Limited is permitted to process 86,400 tonnes of non-hazardous waste wood per year.
On Wednesday, Natural Resources Wales (NRW) said it had no "defensible grounds" to refuse a permit to operate.
Docks Incinerator Action Group (DIAG) said there not had been "adequate scrutiny" of the plans and people's health was at stake.
The incinerator, located between David Davies Road and Ffordd y Mileniwm, will process pre-shredded wood.
The NRW report said off-site nitrogen dioxide levels were "unlikely to exceed" European Union Environmental Quality Standards.
DIAG wants the permit suspended until "all planning conditions are met and suitable monitoring is in place".
"Over the last 14 months our experts have thoroughly scrutinised every aspect of the company's application and considered all representations made to us," said NRW's Nadia De Longhi.
"We have also accepted advice from other experts outside of the organisation on important issues such as people's health and fire prevention.
"We are confident that the company has all the right plans and processes in place to be able to operate this facility without damaging people's health or the environment."
However, opponents, who gathered 10,000 signatures against the plans, vowed to keep campaigning.
Barry councillor Vincent Bailey added: "The fight isn't over, but it just got a whole lot harder."
Max Wallis of Friends of the Earth (Barry and Vale) group called it "unsafe technology" and demanded an independent review of the plant.
He said it should not be allowed close to homes and businesses and was vulnerable to tidal-surge flooding in the docklands areas.
"NRW has been blind to concerns from the local community over the safety risk," he added.