"Congestion was down 60 percent in the capital of France, after five-days of intensifying smog...[The smog] rivaled Beijing, China, which is known as one of the most polluted cities in the world(Source 2)." There's always so many people rushing to get to work in the morning and your car only moves a couple feet per minute from all the backed up traffic but, if there wasn't so many cars on the road, that would never be an issue.