BUCHAREST, Romania (AP) — Officials suspended shipping along Europe's second-longest waterway on Tuesday as a polar spell gripped a large swathe of the continent, causing hardship especially among migrants, the homeless and the elderly. Following strong criticism from aid agencies and others, authorities on the Greek island of Lesbos said they would move 250 refugees from tents at camps into vacant hotel rooms as the heavy snow continued unabated around the country. In Romania, Bucharest Mayor Gabriela Firea on Tuesday ordered schools in the capital to remain closed for the rest of the week as the country battled the bitter cold which has led to travel delays, power outages and a surge in demand for natural gas and power. Farther north in Poland, alarming smog levels led authorities to close schools and kindergartens for two days in the southern city of Rybnik to protect children from noxious fumes, and offer free public transport to try and improve air quality. Poland's capital, Warsaw, offered free public transport on Monday, and the situation improved, although residents complained of coughing and irritated noses and eyes. The smog mainly emanates from substandard fuels, such as coal mud, waste and plastic, burned in poor quality heaters in private homes, air monitoring expert Barbara Toczko told The Associated Press.