The South African Maritime Safety Authority (SAMSA) has approved the use of all kinds of scrubbers in its waters.
The decision was welcomed by shipowners' organisation The Clean Shipping Alliance 2020 (CSA 2020).
In an IMO 2020 advisory notice, SAMSA said open-loop, closed-loop or hybrid systems are accepted until further notice.
Ian Adams, executive director of CSA 2020, said: “We are delighted that South Africa has approved the use of open-loop systems in its waters.
"The use of EGCS improves substantially local air quality and we hope other ports will come to welcome the technology."
CSA 2020 said open-loop scrubbers have been selected for more than 80% of the 2,500 or so ships that will have the exhaust cleaners installed by the end of 2019.
Adams added: “We encourage all port authorities to seek out the available independent studies that provide detailed analysis of wash water discharges and describe the meaningful health benefits that reduced particle emissions can bring to their regions."
CSA 2020 has 37 member shipowners representing 30 shipping sectors and operating, collectively, more than 3000 vessels.