WARSAW, Poland (AP) — The Latest on the cold spell gripping Europe (all times local):

1:30 p.m.

Authorities in Serbia say that a father and son have died from freezing temperatures in the Balkan country's south which has been the hardest-hit by the dayslong cold spell.

Officials say that an 88-year-old man and his 64-year-old son from the village of Duga Poljana were discovered by a man from a neighboring village who delivers bread. Serbian state TV says that the two victims were extremely poor.

Dozens of villages in Serbia's south have been cut off by big snowdrifts. Blizzards and extremely low temperatures have paralyzed parts of the country, and much of Eastern Europe.

Several municipalities in Serbia have declared emergency measures to battle the extreme weather. Authorities have banned river traffic on the Danube and the Sava because of icy conditions.

12:20 p.m.

Alarming smog levels in southern Poland have led authorities to close schools in one city and offer free transport in some places to protect children and try to improve the quality of air.

The government will debate how to fight the smog, after air pollution exceeded warning levels this week in Warsaw and in southern industrial areas experiencing a cold spell.

Children will stay home Tuesday and Wednesday in the low-lying southern city of Rybnik, where drivers were encouraged to use free city transport in an effort to cut down on fumes.

Air monitoring expert Barbara Toczko said Tuesday that the smog chiefly comes from substandard fuels being burned in poor quality heaters in private homes. With snow or precipitation, the pollution hangs over the area where it originated from.

12 p.m.

Romanian authorities have suspended shipping along the River Danube because of bad weather.

Romanian police say that shipping has been suspended midday for an undetermined period along a 900-kilometer (563-mile) stretch of the Europe's second-longest river which crosses Romania.

Romania was gripped by the fifth day of a cold spell Tuesday, which has led to travel delays, power outages and a surge in demand for natural gas and power.

Bucharest mayor Gabriela Firea on Tuesday ordered schools in the capital remain closed for the rest of the week.