Poland has launched legal action to overturn new pollution standards for power stations across the European Union.
But success would compromise the health of people in every EU country, environmentalists claim.
The update to the standards, which were last addressed in 2006, were finally agreed in April this year, via a vote by all member states.
Power plants across the EU have until 2021 to comply with the new agreed levels.
But the Polish government is attempting to erase these with a legal challenge to the General Court of the EU, based on technical arguments.
If successful, the standards would have to be agreed again, setting implementation back by years, activists claim.
Meanwhile, people all over the EU continue to breathe in pollution at levels 10 years out of date. Environmental lawyers have strongly criticised the move.
ClientEarth lawyer Sam Bright said: “This is irresponsible use of the law.
“Poland is clutching at legal straws for political and economic reasons, instead of supporting measures that will protect the health of millions.
“These entirely reasonable standards don’t just apply to Poland – they are designed to clean up plants all over the EU. Knocking them down has implications for every country.
“It took years to get these new standards through. Now they have been agreed, countries should be rallying to clean up their power plants. It’s unconscionable that Poland is trying to throw that out of the window.”
Poland is home to some of the EU’s dirtiest coal power plants, including Belchatow, rated the biggest CO2 polluting thermal power plant in the EU.