Certain places like Chinese cities or Los Angeles might have reputations for smog but Paris had to take drastic measures this week to try to reduce smog levels:

Paris on Monday banned all cars with even number plates for the first time in nearly 20 years to fight sky-high pollution but opted not to extend the measure after an improvement in air quality.

About 700 police officers were deployed to man 60 checkpoints around the French capital to ensure only cars with plates where numbers end with an odd digit were out on the streets, infuriating motorist organisations.

Public transport has been free since Friday to persuade Parisians to leave their cars at home, and at rush hour on Monday morning, authorities noted there were half the usual number of traffic jams as drivers grudgingly conformed to the ruling…

The government decided to implement the ban on Saturday after pollution particulates in the air exceeded safe levels for five straight days in Paris and neighbouring areas, enveloping the Eiffel Tower in a murky haze.

As the article goes on to note, this is likely a longer-term issue. Just how many cars and factories and other sources of air pollution can a large modern city handle before smog is inevitable? With over 12 million residents in the metro area, Paris has a lot of potential car owners.

It is interesting to note that there are motorist organizations in Europe. Such groups were particularly influential in the United States in the first half of the 1900s by advocating for the construction of roads and highways. In an era before the federal government was involved much in highway construction, some local governments responded more to motorists groups.