WARSAW: Authorities in Poland said on Tuesday that six people died in Poland over a 24-hour period as temperatures plunged across Europe. Police urged people to aid those most vulnerable to hypothermia, especially the homeless, as the mercury fell below minus 20 degrees Celsius in some regions. The Centre for National Security (RCB) said in a statement that six victims had died in the last 24 hours, with the total number of deaths from hypothermia reaching 71 since November 1. Local authorities in Poland have also issued smog alerts across the country urging the children and the elderly to remain indoors. The smog has been the result of coal and waste-fired home furnaces which have been in greater use in the winters. A deep freeze across Europe has left at least 40 dead since the weekend, many of them migrants or homeless people. The last winter in Poland was unusually mild but claimed 77 lives, compared to 78 in 2013-2014 and 177 in 2012-2013. Heavy snowstorms also reached Turkey over the weekend, paralysing Istanbul where almost 65 centimetres (25 inches) of snow fell, forcing hundreds of flights to be cancelled on Saturday.