One possible version:

With the development of the economy, more families have bought private cars， thus leading to heavier traffic problems and more serious air pollution. To raise public awareness of energy saving and environmental protection, Car-free Day is launched in 108 cities in China on September 22 every year. On that day, people are encouraged to take public transport，ride bicycles or walk. The campaign has gained much support all over the country, which is a real success. I hope more cities and their residents will take part in this type of activity.