Government is facing a legal challenge over its decision last year to double the amount of sulfur dioxide that coal-fired power plants and refineries can emit.
groundWork, an environmental non-governmental organisation, filed the challenge against Environmental Affairs Minister Nomvula Mokonyane and President Cyril Ramaphosa in the Pretoria High Court, saying the government broke the law by not publishing the amendments for comment before enacting the legislation.
The law is beneficial to power company Eskom and Sasol, which produces fuel and chemicals from coal, it said.
"If the court agrees with groundWork, big sulfur-dioxide emitters like Eskom and Sasol will have to act immediately to reduce their pollution," the organisation, which is being represented by lawyers from the Centre for Environmental Rights, said in a statement.
"This will requite significant capital expenditure."
South Africa relies on coal for most of its power, with Eskom running some of the world’s biggest coal-fired power plants and spending billions building two more.
Albi Modise, a spokesperson for the Department of Environmental Affairs, declined to comment.
The limit of 1 000 milligrams of the pollutant per normal cubic meter is significantly more lax than standards in China and India, according to groundWork. The group said sulfur dioxide leads to increased incidences of low birth weights and still births and contributes to acid rain.