Turin, October 20 - Turin city council on Friday extended its Saturday ban on car traffic to Euro 5 diesel cars, environment chief Alberto Unia said. "On the basis of the PM10 data from the last few days, we have decided to carry on and go to the second level," he said. "We will monitor the situation at the weekend, and if the data fall we will weigh whether to rethink the blocks already on Monday". With the stoppage of the Euro 5 cars, around 250,000 cars have been banned from circulating. Experts said the values of fine-particulate pollution in the atmosphere had broken limits "on several occasions" in the past few days. Meanwhile the National Research Council (CNR) said there is a blanket of fog on the Po Valley due to unseasonably warm temperatures. It said the blanket was due to a combination of "compacted pollutants" and a long lack of rain in the area. On Thursday Turin's town council told residents not to open doors and windows amid the smog outbreak. The call came after the concentration of PM10 particles jumped to 114mcg/cm, more than double the 50 mcg/cm limit. "In such a critical situation," the city environmental department urged citizens to adopt "a series of precautions: avoid prolonged physical activity outdoors and in particular for the elderly, children and individuals with cardio-respiratory problems, to remain as much as possible behind closed doors, also avoiding to open doors and windows". Turin is one of several northern Italian cities on smog alert. The others are Milan and cities in seven Lombardy provinces. Emergency measures were also unveiled Thursday in Emilia-Romagna.