text: Moreover, air pollution is getting out of control. To help, Bogota has a car free day. Millions of Columbians hiked, biked, skated or took buses to work during a car-free day, leaving the streets of this capital city eerily devoid to traffic jams. "These people are generating a revolutionary change, and this is crossing borders," said Enrique Piera, the mayor of Asuncion, Paraguay. The goal is to promote alternative transpertation and reduce smog. Paris typically has more smog than other European capitals. [last] Week Paris had 147 micgrograms of particutate matter per cubic meter compared with 114 in Brussels and 79.7 in Lonon, Reuters found.