Updated

Four environmental groups say they are filing a complaint to the European Union that accuses Poland of violating legal norms meant to control air pollution.

Poland is one of the two most polluted countries in the 28-member bloc, along with Bulgaria, and many parts of the country have faced crisis-level smog this winter. The main cause is people burning poor quality coal, sometimes even plastics and other garbage, in home furnaces that lack filters.

The organizations announced their plans at a news conference in Warsaw on Friday. They said they would gather signatures of support from the public over the next week and file the complaint to the European Commission on Feb. 17.

Those preparing the complaint are ClientEarth, Greenpeace, The City is Ours and Akcja Democracja.