Coal-fired power plants operated by Eskom are emitting pollutants that primarily cause respiratory diseases such as asthma at almost 42 times the intensity of those in China.

Eskom last week said in the six months through September particulate matter emissions deteriorated to 0.92kg/MWh sent out, the highest since 1992, according to the utility.

That compares with an average of 0.022kg for Chinese power plants, according to government figures. China is the world’s biggest producer of power from coal.

The rising emissions, which more than doubled in intensity from last year, are another sign of Eskom’s deteriorating performance. The indebted company is battling to keep its ageing plants running after years of inadequate maintenance and investment amid a slew of corruption scandals.

The result has been almost daily power cuts that are holding back South Africa’s economic growth and it’s also slowing the repairs needed to curb pollution.

“The fact that we’ve got a constrained system does contribute to how quickly we can take it down and how quickly we can do the repairs” to the pollution abatement equipment, Deidre Herbst, Eskom’s environmental manager, said in an interview.

Premature death

Particulate matter is soot generated while burning coal and emitted through the plants’ stacks or chimneys, that’s small enough to get deep into the lungs and even the bloodstream. In addition to asthma and other respiratory complaints, it’s been linked to premature death of people with heart or lung disease.

Eskom has estimated that its pollution, which includes other harmful emissions such as sulphur dioxide, leads to 330 premature deaths a year. Independent studies have indicated a far higher number of fatalities.

Eskom, in a response to queries, blamed the deterioration on “challenges” and technical issues with a range of pollution abatement equipment at the plants. Those include electrostatic precipitators, which use an electric charge to get the dust to stick to a plate rather than being emitted into the atmosphere, as well as fabric filter bags, which collect the soot.

Read: Eskom pollution kills 330 people a year, company says

Measures being taken to cut the pollution include the refurbishment of the precipitators, Eskom said. “This programme is progressing well,” it said, adding that the pollution levels have now fallen to 0.65kg/MWh.

That’s still almost as high as in the year to March, when it was 0.7kg, and well above the low point of the last 25 years when Eskom emitted 0.2kg in the 12 months to March 2007.

The worst performing power plants were Kendal, which produced 2.39kg of particulate matter per megawatt-hour in the period to September, and Matla at 2.49kg.

That would mean Kendal spewing almost 10t of soot into the atmosphere every hour during the first half of the financial year, when operating at full capacity. The utility said there have been improvements at both plants since the end of September due to interventions.

Eskom’s average emissions equated to about three times the South African limit, although many of its plants have applied for and got exemptions. South Africa’s emission limits are considerably more lenient than those in China and India, two countries that have historically had high emission levels from coal-fired plants.

Read: Air pollution skyrockets at Eskom

Those limits have been deemed too high by South African scientists who in studies commissioned by the government said they were harming the health of children living near the power plants. The environment department, which Eskom said has visited plants exceeding emission limits, didn’t respond to a request for comment.