Lhasa city in southwest China's Tibet Autonomous Region is one of the cities with the best air quality in April 2015, according to the Ministry of Environmental Protection.

The ministry compiled air quality data from 74 major cities, and announced that seven of them, including Lhasa, have met the national standards for best air quality on all five monitored pollutant categories throughout April.

The monitored items for the air quality are carbon monoxide, ozone, nitrogen dioxide, and particle pollutants PM10 and PM2.5, which are airborne particles smaller than 10 or 2.5 microns in diameter.

The other well-performing cities are Shenzhen in Guangdong Province, Xiamen in Fujian, Haikou in Hainan, Guiyang in Guizhou, Nanchang in Jiangxi and Kunming in the Yunnan Province.