Datong, in Northern China's Shanxi province, mostly enjoys clear skies. The happiness index is reflected in the city's air quality index.

Statistics from Datong's environment protection department reveal that 137 days in the first half of the year were of good air quality, ranking it No 1 among the 11 cities and districts in the province.

Since April, coal burning boilers with a volume of less than 10 tons have been dismantled in zones where coal use is now banned. The city has concentrated on making heating more effective, trying to replace coal with clean energy. This is especially true of the ancient city area that needs careful protection.

Dust prevention measures are undertaken in all construction sites and city infrastructure projects. Desulfurization and denitration are implemented in power plants and coal storage plants are improved to prevent dust leakage. Motor vehicle exhaust treatment and clean fuel promotion are carried out and outdoor barbecues are only allowed in certain zones installed with gas prevention facilities.

The government has also cracked down on illegal acts with a variety of activities publicizing environmental laws.