text: An effect of extreme car ususe can be smog. Paris, France has the most smog out of all the other European capitals. They had "147 micrograms of particulate matter (PM) per cubic meter compared with 114 in Brussels and 79.7 in london, Reuters found." After days of heavy pollution. A partial driving ban was enforced to clear the city's air. Motorists with even-numbered license plates were told to leave their cars at home. If they didn't do so, they would be charged with a 22-euro fine. The same order wouls be given to odd-numbered plates the next day. Almost 4,000 driver's cars were fined for using their cars.