Seoul's Weekly No Driving Day program is improving air quality, congestion and saving energy. Every year, two million cars stay off the road – decreasing traffic volume by 3.7%. CO2 vehicle emissions are being reduced by 10% - a total of 2 million tons of CO2, delivering annual savings of $50 million USD in fuel costs. The improved air quality is also improving the health of residents, saving the City millions annually. The program works because it is applied during weekdays, which encourages people to use alternate modes of transport to and from work.