Southwest China's Tibet Autonomous Region saw "excellent" or "good" air quality on about 99.6 percent of days in 2019, according to the region's environmental authority.
This is the seventh consecutive year that the region has seen the percentage surpassing 95 points, according to the regional department of ecology and environment.
To improve air quality, Tibet has been keeping steel-smelting, chemical and paper-making projects out of the region.
In recent years, the region has been phasing out old high-emission vehicles, promoting new-energy public transportation, controlling construction dust and planting more trees to improve air quality.