Six people died in Poland over a 24-hour period as temperatures plunged across Europe, bringing the toll of hypothermia deaths in the country to 71 since November, authorities said today.<br/><br/>Police urged people to aid those most vulnerable to hypothermia, especially the homeless, as the mercury sank to<br/>below minus 20 degrees Celsius (minus 4 Fahrenheit) in some<br/>regions.<br/><br/>Local authorities have also issued smog alerts across Poland urging the children and the elderly to remain indoors<br/>as coal and waste-fired home furnaces drove up air pollution to the highest levels recorded in years.<br/><br/>A deep freeze sweeping across Europe has left atleast 40 dead since the weekend, many of them migrants or homeless people.<br/><br/>Heavy snowstorms also reached Turkey over the weekend, affecting its biggest city Istanbul where almost 65<br/>centimetres (25 inches) of snow fall, causing hundreds of flights to be cancelled on Saturday. <br/>