Major Chinese cities saw worsening air quality in January, according to the Ministry of Ecology and Environment (MEE).
The share of average good air quality days for China's 337 cities monitored by the ministry stood at 67.6 percent for the first month of this year, down 3.5 percentage points year on year.
The average densities of major pollutants of PM 2.5 and PM 10 rose 8.2 percent and 5.4 percent year on year respectively.
Of the 168 cities closely watched by the ministry, Linfen, a city in north China's major coal producer Shanxi Province reported the worst air quality, while air quality in Tibet Autonomous Region's capital Lhasa was the best.
The share of good air quality days for Beijing dropped 6.5 percentage points year on year, MEE data showed.