text: Europe the land of open skys, great land, and smog. As seen in source 2: "paris bans driving due to smog" " On Monday motorists with even-numberd license plates were ordered to leave their cars at home or suffer a 22-euro fine ($31)..." even though 4,000 drivers where fined that day, congestion was down around 60 percent in the general capital area of france. Smog " formed by vehicle emissions (mainly from Diesel Fuel) gets traped under a warmer layer of air due to cold nights and warm to hot days. paris itself generally has more smog than most european citys."Paris had 147 micrograms of particulate matter(PM) per cubic meter..." The smog was erradicated so much that the ruling french party decided to do the same for odd-numberd cars the next day. In Source3 : " car-free day is spinning into a big hit in Bogota"  The "car-free day" idea  spreaded to places like Bogota, Colombia and other bib places that even smaller cities joined in. " In a program that's set to spread to other countries, millions of Colombians hiked, biked, skated, of took buses to work during a car-free day..." even in the rain people still participated.