The Health Ministry yesterday imposed a ban on swimming on polluted beaches, declaring several stretches in and around Attica as out of bounds and forbidding bathers from stretches of coastline close to ports, shipyards and industrial sites. According to the decision signed by Minister Mariliza Xenogiannakopoulou, swimming will henceforth be banned at all ports and marinas. Specific areas declared off-limits to bathers include the entire stretch of coast between Piraeus and Perama, between Skaramanga and Aspropyrgos and off the coast of Megara. Swimming will also be banned within 50 meters of pipes channeling sewage and drainage water into the sea. Although bathing in dirty water might be an obvious turnoff for many, experts note that a large number of Greeks continue to swim in dirty water, choosing beaches that are close by or the easiest to get to and showing little concern for the quality of the water. «Swimmers often choose beaches on the basis of habit or what is most convenient,» according to Maria-Adamantia Efstratiou, honorary professor of marine sciences at the University of the Aegean. Young people or those with a strong constitution will likely not be adversely affected by immersing themselves in less than crystal-clear waters, most experts say. But many warn of the problems that can afflict the less physically robust. Efustratiou cited gastroenteritis, skin rashes and ear infections as some of the more common ailments reported by some who swim in polluted water. Experts recommend that concerned citizens check out the website of the Environment Ministry for details of the beaches that have earned blue flags, a stamp of approval awarded as part of a European Union initiative.