The proportion of days with good air quality was 99.4 percent in southwest China's Tibet Autonomous Region in 2020, said a white paper issued by the State Council Information Office Friday.
Last year, Tibet saw its average concentrations of PM10 and PM2.5 declining by 28.1 and 37.5 percent respectively compared with 2015, according to the white paper titled "Tibet Since 1951: Liberation, Development and Prosperity."
