A blanket of sulphur dioxide smog covered Paris Friday, obscuring the top of the Eiffel Tower and prompting Environment Minister Brice Lalonde to issue a call for motorists to leave their automobiles at home.

"The situation is serious though the dramatic situation in certain foreign cities still is a long way off," Lalonde said.A cold snap that took temperatures as low as 25 degrees in the Paris area and a subsequent increase in the use of home heating systems and automobiles was responsible for the smog, ministry officials said.