The European Maritime Safety Agency (EMSA) made public its 2021 report on the environmental impact of those operations, which revealed that container ships, bulk carriers and oil tankers account for 60 percent of the emission of those particles (soot).
It noted that cruise ships, despite making up a low percentage of the total fleet, emit 10 tons per ship and year, a figure lower than the 1.7 recorded for an oil tanker.
The report warned about wastewater discharge: large ships discharge huge quantities of dirty, oily, bilge and ballast water and solid waste (plastics, packages, food waste) into the sea, causing damage to sea ecosystems.
According to EMSA, the main dirty waters discharged into the sea are used to clean exhaust gases of chimneys through filters installed to retain polluting particles.
On the other hand, the report warned about the accidental loss of huge amounts of containers with all their content, which ends up at the bottom of the sea.
Another negative impact is the so-called underwater noise, caused by ships, which disturbs the life of cetaceans and other species that use frequencies to communicate with each other.