When the smog refused to clear in Paris and slowly built up to dangerous levels, the French felt they had to do something. Their answer was the odd/even license plate bans. On Monday, only odd-numbered license plates are allowed in the city. On Tuesday, only even-numbered plates are allowed, and so on.
Unfortunately for the French, all the evidence shows this approach does not work. We can say this because there are license plate programs in place in Athens, Beijing, and Mexico City and their pollution levels have not dropped to any significant degree. Indeed, in Beijing the problem is now far worse than it was when the ban was introduced.
The problem is that everyone with the money can buy a second cheap vehicle with a license plate allowing the owner to drive everyday. Why is this a problem? Because older vehicles with poor pollution controls are usually the cheapest. So, over time, this keeps an increasing number of older, polluting vehicles on the road and smog levels worsen.
The better answers are congestion charges and low emission zones. This gives all drivers a direct incentive to invest in environmentally friendly vehicles fitted with catalytic converters or particle filters. The first LEZ was introduced in Stockholm in 1996 and banned polluting vehicles from the city center. The first congestion charges were introduced in London in 2003 and reduced pollution levels by 12% as more drivers switched to public transport. In 2008 London introduced an LEZ with a further fall of 20% recorded. The policy is therefore to use price to force down the number of vehicles on the road. In most of Europe, this approach is shown to give city dwellers a better quality of air to breathe.
What’s wrong with knee-jerk policies?
The drivers in Paris have suddenly found their freedom to drive arbitrarily restricted. Instead of introducing long-term plans which people can adjust to, the French limit freedom, watch the smog clear, and then go back to the old freedoms. All this does is cause chaos and annoy people. Curiously, the French are pointing to the success of Beijing before and during the 2008 Olympics. Chinese authorities also banned odd/even license plates on a daily rotation. They also shut down many factories that are responsible for poor air quality. When it rained heavily, the Chinese got their good air quality for the Games. Unfortunately, once the Games were over, the factories reopened and people began to buy second vehicles. The result has been increasingly dangerous levels of pollution in the Chinese capital.
A classic example of more serious pollution comes from Bogota where drivers were banned from driving at peak hours. They simply decided to drive more miles at off-peak times to get where they wanted to go.
When making policy, politicians have to remember people will act rationally to the regulations and laws put in place. If there’s a way round the laws, you can be sure someone will work it out and post details online.