In fact, the Government of Pakistan, Ministry of Maritime Affairs (Ports & Shipping Wings) published a circular in which clarified its stance on scrubbers:

The discharge of wash-water from open-loop scrubbers is prohibited in Port. While in the Port, vessels fitted with hybrid type of scrubbers should switch to the closed-loop mode of operations. As for vessels fitted with open-loop scrubbers, they would need to switch over to compliant fuel instead.

Meaning that the circular recommends vessels to switch off the open-loop scrubbers before their arrival in ports waters. In that case, it will be easier to prevent and deal any operational issues on time, before entering Pakistani waters.

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Moreover, Pakistan's Ministry of Maritime affairs advises members with ships fitted with scrubbers, to take a note of the above-mentioned circular and follow the local regulations.

Concluding, several days ago Suez Canal Authority (SCA) also issued a circular advising vessels not to use open-loop scrubbers during a transit from the Canal, so that wash water is not discharged.