In fact what you see in the background is smoke not fog nor smog. Despite the shot has been made during 2005 November hard riots in Paris suburbs this smoke comes from what I assume is an incineration plant. In any case, the suburbs you can see cannot burn cause they are the richest of Paris. To get the chance to shoot some smoke coming from many burning cars, schools, gymnasium, day nurseries (yes!), buses, I would have turned myself of 180 degrees onto the East to see the suburbs were I live.