Environmental activist groups have filed an appeal against emission limit exemptions granted to South African state-owned power utility Eskom Holdings SOC Ltd. at a number of its coal-fired power plants.

Earth Life Africa and groundWork filed the appeal to the Environment Department, which oversees the work of the air quality officer, on Thursday, according to Nicole Loser, a lawyer at the Centre for Environmental Rights, a legal organization representing the activists.

National Air Quality Officer Thuli Khumalo partially approved Eskom’s application to breach emission limits at the Tutuka, Majuba, Kendal and Kriel power plants and fully approved applications at the Grootvlei, Camden, Hendrina and Komati coal-fired power plants. A request to delay compliance at the Acacia and Port Rex natural-gas facilities was also granted.

Eskom, which supplies almost all of South Africa’s power, is the country’s biggest polluter and has conceded that pollution from its plants leads to the deaths of about 320 people every year. The government has separately been sued for failing to enforce limits on pollutants such as sulfur dioxide and particulate matter.

The activists argued in their documents that Eskom could not lawfully apply for the exemptions and was in breach of a number of other regulations. While Khumalo made her decision on Oct. 30 it was only publicly announced in December.

Khumalo did deny Eskom’s application to significantly breach sulfur dioxide emission limits at its Medupi plant and sulphur dioxide, nitrogen dioxide and particulate matter at its Matimba plant.

Eskom has appealed the decision. It’s appeal is yet to be released publicly.

The company said that it would cost R300-billion to make all of its plants fully compliant and as it could not afford this the rulings could lead to the closure of 16 000 MW of generation capacity, or about a third of its potential output.